1 · Upload
Choose or drag in a TIFF, PNG, or JPEG. The calculation stays in this browser and the image is not uploaded. Sign in to use your own image; it uses no credits for now. If you have no image yet, start with the example, no account needed.
Local calculation · Adjustable boxes
Western blot quantification
Western blot densitometry: automatically detect lanes and bands, then measure relative integrated density without tracing every band by hand in ImageJ. Upload a TIFF from the imager; PNG and JPEG open too. TIFF uses the samples stored in the file. PNG and JPEG use the browser’s 8-bit decode.
How it works
How to Quantify a Western Blot with FigPad
Western blot densitometry detects lanes and bands, then measures relative integrated density from the background beside each band. Open a TIFF, PNG, or JPEG instead of tracing every band in ImageJ. Adjust the boxes and export the result.
2 · Frame one row
Draw a box around the row you want to measure and leave a little membrane above and below it, or use the whole image. Then enter how many lanes you loaded so the detected count can be checked. Skip this if you are unsure.
3 · Review
Drag a box to move it, or an edge to resize it. Use Add band for a miss. Merge asks you to click the two bands to combine. Split cuts the selected lane into a left and a right column. Reject a false band, or restore one you removed.
4 · Export
Download CSV, Excel, and an overlay of the boxes, and copy a methods paragraph. The values are relative integrated density for comparison within this image. They are not normalized to a loading control.
Western Blot Densitometry FAQ
What images can I upload?
Upload a TIFF, PNG, or JPEG up to 40 MB. TIFF reads the samples stored in the file and supports uncompressed or PackBits images at 8, 16, or 32 bits; LZW is not supported yet. PNG and JPEG use the browser’s 8-bit decode. A 16-bit TIFF from the imager is the better source. JPEG opens, but compression has already changed the pixels, so treat the numbers as approximate.
Do I need an account, and does it use credits?
Sign in to quantify your own blot image. Detection, box edits, and exports use no credits for now. The example works without an account.
Can I try it for free?
Yes. Select Try the example to walk through cropping, the lane-count check, box edits, and export without signing in. The example is a generated blot, so you can learn the steps before using your own membrane.
Is the automatic detection always right?
Review it. Very faint bands and uneven spacing can be missed, and saturated bands can stick together. Check the lane count, then add, reject, merge, or split before using the result. On public membranes, the stronger bands ranked in the same order as ImageJ Gel Analyzer lane profiles. That is not an error guarantee for every blot.
How do I add, merge, or split a band?
To add one, select Add band and click the missed spot, then drag the box to move it or an edge to resize it. To merge, select Merge and click the two bands; no other band may sit between them. To split, select a band and choose Split, which cuts that lane into two columns. Before you click the image, press Esc or Cancel to leave add or merge.
What does the exported number mean?
Integrated density is the signed sum of pixels inside the box after subtracting the background. The background is the median of nearby rows above and below the band, excluding rows that fall inside another band. The unit is arbitrary and is only comparable within the same image. There is no loading-control normalization. If pixels inside a band reach the end of the measurement range, the methods text says the density may be too low.