1. Add an image. Take a photo of your gel, choose an image file, or tap Try a sample blot to practise on a built-in example.
2. Crop. Drag the frame around the gel, tap Auto-straighten, then Apply & continue. Skip Adjust unless the gel is too faint or has bright bands on a dark background.
3. Lanes. Lanes are found automatically. Type your sample names, separated by commas, and tap Apply.
4. Marker. Check that the right lane is the marker and pick your marker from the list. Its band sizes appear next to the bands.
5. Highlight. Tap your band of interest. It is outlined and its size is estimated from the marker.
6. Export. Download the labelled figure as PNG, JPEG or SVG.

Need quantification, smile correction or band matching? Switch to Advanced analysis at the top of the tool. Your image, lanes, names and marker carry over.

You can move between steps at any time with the tabs. Only re-applying the crop clears your work, and the tool asks before it does.

Controls that appear on every step

− / + and the percentage

Zoom the image out or in (up to 800%). Zooming helps you place lanes and band edges precisely on a phone.

Fit

Return to 100% so the whole image fits on screen.

Pan

Turn this on to scroll around a zoomed image with your finger without accidentally adding or moving anything. Turn it off again to edit.

Quick figure / Advanced analysis

Switches between the two modes. Everything you have done is kept when you switch.

Step tabs

Jump to any step of the current mode. Steps are greyed out until an image is loaded.

Keyboard (computers)

Delete or Backspace removes the selected lane, band or reference line. Arrow keys move the selection by 1 pixel (hold Shift for 5). Esc clears the selection.

Quick figure

For labelling a gel for a notebook, a slide or a paper. Steps: Photo, Crop, Adjust, Lanes, Marker, Highlight, Export. Only the marker lane and the bands you tap are marked; nothing is quantified.

Advanced analysis

For measuring. Steps: Photo, Crop, Adjust, Lanes, Bands, Rf lines, Calibrate, Results, Export. Finds every band automatically, corrects uneven running, calibrates size and amount, and compares lanes.

Switching

Use the switch above the step tabs. Image, crop, lanes, sample names, marker and highlighted bands are shared, so you can start quick and switch to advanced later. Highlighted bands are outlined in both modes.

In this guide, sections marked Quick or Advanced belong to one mode only. Sections marked Both appear in both modes.

Load the gel or blot you want to analyse. Everything happens inside your browser: the image is never uploaded to a server.

Take a photo

Opens the phone’s rear camera. On a computer it opens a normal file picker instead.

Choose an image file

Pick an existing photo or an imager export. JPEG, PNG and WebP work in every browser; iPhones convert HEIC photos automatically. Most browsers cannot open TIFF, so export TIFF files from your imager as PNG first. Very large images are scaled so the longest side is 2400 pixels.

Try a sample blot

Loads a built-in western blot with a 10-band protein ladder, two target bands, a loading control, a slight tilt and a “smiling” run. It is the quickest way to learn the tool, because every feature has something to work on.

Open a saved project

Reopens a .gelproject.json file saved in step 9, including the cropped image, lanes, bands, calibration and export settings. The project opens at step 5.

Drag and drop, or paste

On a computer you can drop an image file onto the tool, or paste a copied image with Ctrl/⌘+V.

Tips for a good phone photo

• Lay the gel or film flat and light it evenly. A light box, or a white screen at full brightness behind the film, works well.
• Hold the phone parallel to the gel and close enough that the gel fills most of the frame.
• Avoid reflections, shadows and glare across the lanes. Turn off the flash if it creates a hotspot.
• For quantification, an imager or scanner file is always better than a phone photo.

Straighten the image so lanes run vertically and bands run horizontally, then cut away everything outside the gel. All later steps work on the cropped image.

Rectangle

A straight crop box. Drag the round corner handles, or the bar-shaped handles on each edge, to resize it. Use this mode for scans and photos taken straight on.

4-corner perspective

Drag each of the four handles onto a corner of the gel, even if the gel looks like a trapezoid because the photo was taken at an angle. The area is stretched back into a true rectangle. Use this mode when the phone was not parallel to the gel.

Fine rotation slider

Rotates the image between −45° and +45° in 0.1° steps. The − and + buttons beside it nudge it by 0.1°. Line the bands up with the grid lines inside the crop box.

Auto-straighten

Tests every angle between −15° and +15° and picks the one that makes the bands most horizontal. Check the result and fine-tune with the slider if needed.

↺ 90° and 90° ↻

Turn the image a quarter turn, for example if the photo was taken sideways. The wells should end up at the top.

Flip

Mirrors the image left to right, for film that was scanned or photographed from the back.

Reset

Sets rotation back to 0° and restores the default crop box.

Apply & continue

Cuts out the selected area and moves to step 3.

Lanes, bands and Rf lines are positioned on the cropped image. If you come back and apply a different crop, they are cleared, and the tool asks before it does this.

Make the bands easy to see and tell the tool which way round your image is. The analysis treats dark pixels as signal.

Invert

Turn this on when the bands are bright on a dark background (ethidium bromide or SYBR gels, fluorescent or many chemiluminescence imager exports). It is the one setting on this step that changes measurements, because it decides what counts as signal.

Grayscale

Shows the image in shades of grey (recommended). Turn it off to see the original colours, for example with Coomassie or Ponceau stains. Measurements always use brightness, whatever this is set to.

Black point

Everything darker than this value is shown as pure black. Raise it to deepen faint bands.

White point

Everything lighter than this value is shown as pure white. Lower it to clean up a grey background.

Gamma

Brightens (above 1) or darkens (below 1) the mid-tones without moving the black and white points.

Auto contrast

Sets the black and white points automatically from the image’s darkest and lightest pixels, ignoring the extreme 0.4% and 1.5%.

Reset

Restores the original display (black 0, white 255, gamma 1, grayscale on). Invert is left as it is.

Black point, white point and gamma only change how the image looks on screen and in the exported image panel. Band volumes are always measured on the unadjusted pixels. The same adjustment is applied to the whole image, as journals require.

Mark where each lane is and name your samples. Lanes are detected automatically the first time you open this step. Lane 1 is assumed to be the marker (shown in orange); you can change that in the Marker step (Quick) or the Calibrate step (Advanced).

On the image

Tap empty space

Adds a lane at that position.

Drag a lane

Moves it sideways.

Drag a lane’s edge handle

Makes that lane wider or narrower. Only this lane changes.

Drag the dashed Origin line (Advanced)

Place it at the bottom of the wells, where the samples started running. Nothing above it is analysed. It defines Rf 0.

Drag the dashed Front line (Advanced)

Place it at the dye front or the lowest point you want analysed. Nothing below it is analysed. It defines Rf 1.

Buttons and settings

Detect lanes

Finds lanes automatically using the settings below. This replaces all current lanes and removes their bands.

Clear all

Removes every lane and band.

Number of lanes

Leave at auto, or set the exact number of lanes on your gel. Giving the number makes detection much more reliable on faint or uneven gels.

Sensitivity

How strong a lane must be, compared with the strongest lane, to be detected. Lower it if faint lanes are missed; raise it if gaps between lanes are picked up as lanes.

Minimum lane spacing

The smallest allowed distance between two lane centres, in pixels. Auto estimates it from the gel’s repeating pattern. Increase it if one wide lane is split into two.

Lane width

Width given to detected lanes, as a percentage of the distance between lanes. 70–80% suits most gels.

Ignore image edges

Ignores this percentage of the image on the left and right, so the gel’s borders are not mistaken for lanes.

Default lane width

The width, in pixels, of every lane that has no width of its own.

Use default width for all lanes

Removes individual widths so all lanes share the default width again.

Reset origin/front (Advanced)

Puts the Origin and Front lines back near the top and bottom of the image and removes any bends added in step 6.

Sample names, comma separated

Type the names of all lanes in order, for example M, Ctrl, siRNA 1, siRNA 2, then tap Apply. The labels are used in tables and on the figure.

Lane list

One row per lane. Tap the number to select the lane. Type a label, or a width in pixels (leave it blank to use the default). × deletes the lane and its bands.

Tell the tool which lane holds your molecular weight marker (ladder) and which marker you used. Its bands are found automatically and given their sizes from top to bottom. These sizes appear beside the gel in the figure, and they are used to estimate the size of the bands you highlight.

On the image

Tap empty space in the marker lane

Adds a marker band that was missed. It snaps to the nearest band and the sizes are re-assigned from top to bottom.

Drag a marker band

Moves it up or down if it is slightly off.

Orange numbers

The size given to each marker band. A ? means that band has no size.

Panel

Marker lane

The lane that contains the marker. Choosing another lane finds its bands automatically.

Marker (ladder)

Built-in protein markers (10–250 and 10–180 kDa) and DNA ladders (1 kb, 100 bp), or Custom sizes.

Sizes, top to bottom

The marker’s band sizes from the top of the gel to the bottom. Edit them to match your marker’s datasheet; editing switches the marker to Custom sizes. The unit menu sets kDa, bp or kb.

Find marker bands again

Re-detects the bands in the marker lane and re-assigns the sizes.

Re-assign sizes top to bottom

Gives the marker bands the listed sizes in order, for example after you added or removed a band.

Band list

One row per marker band. Type a different size, clear it to leave the band unlabelled (for example the dye front), or remove the band with ×.

If a weak marker band is missed, all sizes below it shift by one. Compare the orange numbers with the image, tap the missing band to add it, and the sizes re-assign themselves.

Point out the bands that matter, for example your purified protein or the band that changes between samples. Highlighted bands are outlined on the figure and get an arrow label with their name or estimated size.

On the image

Tap a band in a sample lane

Highlights it. The outline snaps to the band, and its estimated size is shown above it.

Tap a highlighted band

Selects it (yellow). Drag the yellow handles on its top or bottom edge to fit the outline to the band, or drag the middle to move it.

Dashed grey boxes

Bands found in Advanced analysis that are not highlighted. Tap one to highlight it.

Panel

Outline colour

Colour of the outline on screen and in the figure. Red and yellow stand out on most gels; use white on dark gels.

Outline on figure

Untick it to keep only the arrow label without a box around the band.

Highlighted bands list

One row per highlighted band, with its lane and estimated size. Type a label (for example His-MBP-TEV, 45 kDa) to show on the figure; leave it empty to show the estimated size. Remove a highlight with × or Delete.

Estimated sizes need at least two sized marker bands. Sizes outside the marker range are marked as such and are rough. SDS-PAGE sizes are approximate; tags, modifications and gel percentage all shift a band.

Each lane is turned into an intensity profile: a curve that rises wherever there is a band. The background is subtracted and peaks are found automatically the first time you open this step. Each band has a start, a peak and an end; its volume is the area between the start and end, above the background.

On the image

Tap a band

Selects it (yellow). Its details appear in the panel and in the profile below the image.

Tap empty space in a lane

Adds a band. It snaps to the nearest peak and its edges are set automatically.

Drag a band

Moves the whole band up or down.

Drag the top or bottom edge

Changes where the band starts or ends. Select the band first to see the yellow edge handles.

Lane profile (under the image)

‹ and ›

Show the previous or next lane’s profile.

Black line

The profile, from the origin (left) to the front (right).

Orange dashed line

The background that is subtracted.

Shaded areas

The measured bands. The selected band is yellow; drag its yellow handles to move its start or end. Tap a gap to add a band there.

Buttons

Detect in all lanes

Re-runs peak detection everywhere with the current settings. Labels and quantity standards are kept for bands found at the same position.

Selected lane only

Re-runs detection in the lane shown in the profile, leaving the other lanes untouched.

Clear

Removes all bands.

Profile & background settings

Profile width

How much of each lane’s width, centred on the lane, is averaged into the profile. 60–80% avoids the uneven lane edges.

Profile smoothing

Evens out noise and film grain. Keep it low (0–2) so neighbouring bands stay separate.

Background: Rolling ball

Imagines a ball rolling along underneath the profile and removes everything below it. It follows a slowly changing background well. This is the default and suits most gels and blots.

Background: Valley to valley

Draws a straight baseline from the start to the end of each band. Good for well-separated bands on a background that changes from band to band.

Background: Constant (percentile)

Subtracts one flat level from the whole lane, taken as the chosen percentile of the profile. Good for clean scans with an even background.

Background: None

Measures raw signal. Use it only when the background has already been removed, for example by your imager.

Rolling-ball radius

Size of the ball in pixels. Make it larger than your widest band, or wide bands get flattened. Auto uses one eighth of the image height.

Percentile

For the constant background: 10% means the background is set at the level that 10% of the lane falls below.

Peak detection settings

Sensitivity (min. prominence)

How much a peak must stand out from its surroundings, as a percentage of the lane’s tallest peak. Lower it to catch faint bands; raise it to ignore noise.

Minimum band separation

Two peaks closer than this, in pixels, are treated as one band. Lower it for tightly spaced bands.

Band edge threshold

Where a band’s start and end are placed: where the signal drops below this percentage of the band’s peak, or at the dip between two bands, whichever comes first. Lower values give wider bands.

Max bands per lane

Keeps only the strongest bands in each lane. The ladder lane instead uses the number of sizes in your ladder.

Peak smoothing

Smooths the profile only for finding peaks, so the measured values are not affected.

Selected band card

Start, Peak, End

The band’s position in pixels from the top of the cropped image. Type exact values if you prefer this to dragging.

Label on figure

Text used for this band in the exported figure and tables, for example GAPDH. Without a label, the figure shows the estimated size.

Re-fit to peak

Moves the band to the nearest peak and recalculates its edges.

Show on figure

Untick it to keep the band in the analysis but leave it unlabelled on the figure.

×

Deletes the band.

Summary line

Shows the band’s Rf, estimated size (after step 7), volume and peak height.

Rf is how far a band moved, from 0 at the origin to 1 at the front. Sizes and band matching are calculated from Rf. Gels often run unevenly: outer lanes run slower (“smiling”), or the whole gel runs at a tilt. Then the same protein sits at different heights in different lanes. Rf lines fix this: each line marks something that ran the same distance in every lane, and you bend the line to follow it.

On the image

Round nodes

Each line has one node per lane. Drag a node up or down to follow the line in that lane. Positions between nodes are interpolated.

Drag a line between nodes

Moves the whole line up or down, keeping its shape.

Tap empty space

Adds a new reference line (red) at that height. Put it on a band that every lane shares, such as a loading control or the dye front.

Panel

Apply distortion correction

On: Rf in every lane is calculated from the bent lines and expressed on the reference lane’s scale. Off: Rf uses straight origin and front lines only. Switch it off and on to see how much the correction changes your sizes.

Reference lane

The lane whose positions define the corrected scale, normally the ladder lane.

Line list

O = origin, F = front, R = reference line, with the line’s Rf. Tap a row to select the line. “Adjusted” means it has been bent; “straight” means it has not.

Snap selected line to bands

Moves each lane’s node onto the nearest band (or peak) within a short distance. This is the fastest way to trace a shared band across all lanes.

Straighten selected

Makes the selected line straight again, at its height in the reference lane.

Delete selected

Removes the selected reference line. The origin and front cannot be deleted.

Recommended workflow for a smiling gel

1. Select the Front line and tap Snap selected line to bands so it follows the dye front in every lane.
2. If a band is present in all lanes (a loading control, for example), tap it to add a reference line there and snap it as well.
3. Check the nodes by eye and drag any that landed on the wrong band.

This step has two independent parts. Molecular weight uses your ladder to give every band an estimated size. Quantity standards use bands of known amount to convert volumes into amounts. You can use either part, both or neither.

Molecular weight

Ladder lane

The lane that contains your marker. It is shown in orange.

Ladder

Built-in ladders for proteins (10–250 and 10–180 kDa) and DNA (1 kb and 100 bp). Choose Custom sizes for any other ladder.

Sizes, top to bottom

The ladder’s band sizes from the top of the gel (largest) to the bottom, separated by commas. Editing them switches the ladder to Custom sizes. Always check them against your ladder’s datasheet, because ladders from different suppliers differ.

Unit

kDa for proteins, bp or kb for DNA and RNA.

Assign sizes top to bottom

Gives the ladder lane’s bands the sizes in order, starting from the top. Use it again after adding or removing ladder bands.

Ladder table

One row per ladder band. Size can be edited; clear it to leave a band out of the calibration (for example a dye front or a smear). Fitted is the size the curve predicts for that band. Error is the difference in percent and turns red above 5%, which usually means a size is on the wrong band.

Curve: Point-to-point

Joins neighbouring ladder bands with straight lines on a log scale. It follows any ladder closely and is usually the most accurate choice. Its error column shows the leave-one-out error: how well each band is predicted when it is left out.

Curve: Linear regression

One straight line of log(size) against Rf. Simple, and shows how linear your gel is, but less accurate across a wide range.

Curve: Quadratic regression

A gently curved line. A good compromise for gradient gels or wide ladders.

R² and the chart

R² shows how well the points fit (1.000 = perfect). The chart plots each ladder band (dots) and the curve.

Sizes outside the ladder’s range are extrapolated and marked with *. Treat them as rough estimates only.

Quantity standards

Unit

The unit of your standards, for example ng, µg or pmol.

Model: Linear

Volume = a + b × amount. The usual choice when standards are in the linear range.

Model: Linear through origin

Volume = b × amount. Works with a single standard, but assumes zero amount gives zero signal.

Model: Power (log-log)

Fits a curve that bends, as blots often do at high amounts. Needs at least two standards, ideally more.

Adding a standard

Tap a band of known amount on the image, type the amount in the box that appears, then tap Add standard. Standards are marked with their amount on the image.

Standards list

Edit an amount directly, or remove a standard with ×. The two columns show the amount calculated back from the curve and its error in percent (red above 15%).

With a quantity curve in place, every band gets an Amount column in step 8. Standards should be on the same gel and should cover the range of your samples.

Three views of your data. Tap a row in the band table to highlight that band on the image.

Bands

Normalize

No normalization shows raw volumes. % of lane total divides each band by the total of its lane, which corrects for uneven loading when bands make up the whole lane. To loading control band divides each band by the loading control in the same lane (for example actin, tubulin or GAPDH).

Loading control

Appears when normalizing to a loading control. Choose the band class (see Band matching below) that is your loading control.

Relative to lane

Divides each value by the same band in the chosen lane, so that lane becomes 1.00. Choose your control lane to read fold changes directly.

Lane, #, Label

The lane number (M = ladder), the band’s position in its lane from the top, and its label.

Rf

Corrected migration distance (0–1).

Size

Estimated size from step 7. * means extrapolated.

Volume

Background-corrected band area × lane width, in arbitrary units (a.u.).

% lane and % max

The band’s share of its lane’s total, and its size compared with the largest sample band on the gel.

Norm., Rel. lane, Amount

Shown when normalization, a reference lane or a quantity curve is set.

Class

The group of matching bands this band belongs to, shown with a colour dot.

Download CSV

Saves the full table for Excel, Prism or R, including band edges, raw volume and peak height.

Band matching

What it shows

Bands in different lanes at the same corrected Rf are grouped into a band class (one row each). A dot means the lane has that band. While you are in step 8, bands on the image are coloured by class.

Matching tolerance

How close two bands’ Rf values must be to count as the same band. Raise it if one band is split into two rows; lower it if two different bands are merged.

Include ladder lane

Also matches ladder bands. Usually left off.

Show volumes

Shows each band’s volume in the matrix instead of a dot.

Download CSV

Saves the matrix with 1 and 0 for present and absent, or with volumes.

Lane similarity

What it shows

How alike each pair of lanes is, from 0 (no shared bands) to 100 (identical band pattern), using the Dice coefficient. Useful for comparing banding patterns, such as restriction digests, PCR fingerprints or purification fractions.

Download CSV

Saves the similarity matrix.

Make a figure of the gel, and in Advanced analysis also a figure of the lane profiles. The image shows a live preview of the panel you are building.

Image panel

Lanes in panel

Untick lanes to leave them out of the figure.

Between non-adjacent lanes

When you leave out lanes in the middle, the remaining parts are joined. Splice line draws a thin vertical line at each join and White gap leaves a space. Most journals require one of these, so Nothing is not recommended.

Gap

Width of the white gap in pixels.

Trim top / Trim bottom

Cuts empty space from the top or bottom of the gel, as a percentage of its height.

Title

Optional text above the figure, for example the antibody and exposure. It also names the downloaded files.

Lane labels

Horizontal, 45°, vertical, or hidden. Long labels read best at 45° or vertical.

MW markers

Puts the ladder sizes with tick marks on the left or right side, or leaves them out.

Band labels

Adds arrows with band names on the side opposite the markers. A band’s label text is used, or its estimated size if it has none. Bands at the same height share one label. In Quick figure only highlighted bands are labelled; in Advanced analysis every band set to Show on figure is.

Outline highlighted bands, Outline colour

Draws a box around each highlighted band in the chosen colour.

Border

Draws a thin frame around the gel.

Text size

Size of all text in the image panel, in pixels.

Profile panel (Advanced)

Lanes in panel

Choose which lane profiles to draw.

Layout

Stacked draws one row per lane. Overlaid draws all lanes in one plot in different colours, with a legend.

X axis

Rf, molecular weight (log scale, needs a ladder from step 7) or pixels.

Signal

Raw profile with background shows the measured curve with the background as a dashed line. Background-corrected shows the curve after the background is subtracted.

Shade band areas

Fills the measured area of each band.

Band labels

Writes labels or estimated sizes above the peaks.

Same y scale for all lanes

In the stacked layout, uses one intensity scale so heights can be compared between rows.

Width, Row height / Height, Text size

Size of the plot and its text, in pixels.

Text & output (both panels)

Font

Arial/Helvetica suits most journals. Times, Courier and Verdana are also available.

Line width

Thickness of borders, ticks and curves.

Background

White, or transparent for placing the figure on a coloured slide. JPEG files are always white.

Format

PNG for figures (sharp and lossless). JPEG for small files. SVG keeps text and lines editable in Illustrator or Inkscape.

Scale

Multiplies the pixel size of PNG and JPEG exports. 2× or more gives sharp text for print.

Resolution tag

The dpi value written into the PNG or JPEG file. It does not change the pixels, but tells Word, PowerPoint and journal systems how large to print the figure. The line below shows the resulting size in cm.

Buttons

Download panel

Saves the panel currently shown (image or profile) in the chosen format.

Share…

Appears on phones that support it. Sends the panel straight to email, messages, cloud storage or other apps.

Download profile data (CSV, Advanced)

Saves the profile of each selected lane, row by row: position, Rf, size, raw signal, background and corrected signal.

Save project (.json)

Saves the cropped image and the whole analysis in one file. Open it later with Open a saved project in step 1 to continue or change the figure. Keep it with your raw data.

Start over with a new image

Clears everything after asking you to confirm. Your detection and ladder settings are kept for the next gel.

Lane

One vertical track of the gel, loaded with one sample.

Ladder (marker)

A lane with bands of known size, used to estimate the size of other bands.

Origin and front

The start of the run (bottom of the wells) and the end of the analysed region (usually the dye front).

Rf

Relative migration distance, from 0 at the origin to 1 at the front.

Profile

The average intensity across the middle of a lane, plotted from top to bottom. Each band shows up as a peak.

Background

Signal that is not from a band (stain, film fog, uneven light). It is subtracted before measuring.

Volume

The background-corrected area of a band’s peak multiplied by the lane width. Also called integrated density. Its units are arbitrary (a.u.).

Prominence

How far a peak rises above the lowest point between it and any taller neighbouring peak.

Band class

A group of bands in different lanes that ran to the same corrected Rf, which most likely means they are the same molecule.

Extrapolated (*)

A size outside the range of the ladder, estimated by extending the curve. Less reliable.

Dice similarity

2 × shared bands / (bands in lane A + bands in lane B), as a percentage.

Saturation

When a band is so strong that the darkest pixels are clipped. Its volume is then too low and should not be quantified.

• Compare within one image. Phone cameras adjust exposure and contrast automatically, so values from different photos are not directly comparable.
• Avoid saturated bands. If a band is solid black in the middle (or solid white after inverting), its volume is underestimated. Use a shorter exposure for quantification.
• Use standards when amounts matter. Phone photos and film are not linear. A dilution series of standards on the same gel, with the power model, gives far more reliable amounts than raw volumes.
• Normalize to a loading control for western blots, and report fold changes relative to your control lane.
• Check sizes against the ladder datasheet. Sizes depend on the ladder, the gel percentage and the buffer, and extrapolated sizes (*) are approximate.
• Keep your originals. Save the original image and the project file together, so the analysis can be checked and repeated.
• Confirm key results on an imager. This tool is designed for quick analysis and figures; important quantification should be confirmed on calibrated equipment.
• Privacy. Images and results never leave your device. Nothing is stored after you close the page unless you save a project file.