Resize an image to 40 KB
Resize a photo to under 40 KB online for free, in your browser with no signup.
Jump to the toolYour workspace File size · Preview · DownloadPrivate by default
Runs on this device. The first use downloads a 56 to 135 MB model once. Nothing is uploaded.
- Open a photoDrop, paste or choose one.
- Set the sizeType it, or pick a common size.
- DownloadSee the file size before you save.
Processed on your deviceNo watermark. No signup.
All five of our test photos fitted at the default 1600 pixels, at quality 5 to 11. A busy city scene only fitted at quality 5, the lowest, so a busier photo may need a smaller width.
What to expect at this size
These are measured figures, not estimates. Five photographs were run through this page's own engine and the results written down.
The range is what varies between an easy photograph and a hard one: a flower against a blurred background compresses far better than a street full of signage.
- File size produced
- 35.4 KB to 39.8 KB
- Quality it settles on
- 5 to 11
- Photos that hit the target
- 5 of 5
- Photographs used
- 5
- Measured on
Why do forms ask for this size?
A 40 KB limit usually comes from an upload form, for a photo or a scanned document. It is the smallest target at which all of our test photos kept the default 1600 pixel width.
The quality left is very low, though. If your form gives pixel dimensions, use them: a smaller photo keeps more detail in each pixel.
Uploading a China visa photo? That form asks for 40 to 120 KB, so 40 KB is its floor, not its ceiling. China visa photo size.
What is the difference between resizing and compression?
The main difference between resizing and compression is the measurement you change. Resizing changes width and height in pixels. Compression reduces file size in bytes.
A photo can have the correct dimensions and still exceed an upload limit, so check both requirements.
If you need both, set the dimensions first and then adjust quality or the file size target. Work from the original and download once to avoid repeatedly recompressing a saved JPEG.
PNG has no quality setting, so a PNG over the target is reduced to fewer colours instead, keeping as many as fit. The meter shows the count.
Screenshots and graphics usually survive this with no visible change. A photograph needs many colours, so bands of flat colour can appear at a small target, and JPEG is then the better format.
What happens to your photo?
Your selected photo is processed in your browser, without an image upload to a server. The page may download code and codecs needed for editing.
Save your result before closing the tab; unsaved edits are kept in memory rather than in an online account.
Common questions
What quality will my photo have at 40 KB?
Very low, and it depends on the detail. At 1600 pixels our city scene got quality 5, the forest waterfall 6, the mountain range 10 and the sunflower 11.
The city scene was at the lowest quality the search tries, with 1,955 bytes to spare. A busier photo will not fit at 1600, and the editor then suggests a smaller width.
My form says 40 KB. Is that 40,000 or 40,960 bytes?
This tool counts 1 KB as 1,024 bytes, so its 40 KB target is 40,960 bytes. A form that prints its limit as 40.96 kB is counting the same way.
A form that counts 40,000 is stricter. Two of our five photos came out at 40,497 and 40,782 bytes, over that reading. Type 39 in the exact size box to aim for 39,936 bytes; our largest was then 39,278.
My form says 40 KB to 120 KB. Should I aim for 40?
No. There, 40 KB is the smallest file the form accepts, and this page makes files under 40 KB, which that form would refuse.
China's online visa form is one example. Its own page opens the editor at the right pixel size and keeps the file inside that range.
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