Compress a JPG to 5 KB for signatures, thumbnails, and tiny uploads
5 KB is about as small as an image upload limit gets. You'll see it on older application and exam portals, on signature and thumb-impression boxes, in HR and banking systems that store images in a database, for email signature logos, and for profile thumbnails in apps with strict storage budgets. At that size you're almost always working with a signature, a small thumbnail, or a simple mark rather than a full photo.
This tool gets any image under 5 KB, or any size you choose, while keeping it as readable as that budget allows. Everything runs in your browser, so signatures and ID images never leave your device.
How to use it
- Choose one or more images, or drop them onto the box. JPG, PNG, WebP, GIF, BMP, and AVIF all work, and the result is always a JPG.
- Keep the 5 KB target, pick 3, 8, or 10 KB, or type your own.
- For a signature, turn on Black and white and set What matters most to "Sharpness."
- If the form lists pixel dimensions, such as 140 × 60 for a signature, enter them in the exact size boxes.
- Hold Hold to compare to check the result, then download it or save a batch as a ZIP.
Why 5 KB is so tight
Every JPG carries a fixed amount of overhead before any picture data: headers and the tables the decoder needs to rebuild the image. That overhead takes several hundred bytes, which is a noticeable share of a 5,000-byte budget. What's left has room for roughly 20,000 to 80,000 pixels at a readable quality, about the size of a small thumbnail.
| Kind of image | Size that fits in 5 KB, roughly | Result |
|---|---|---|
| Signature on white paper, black and white | 300 × 100 to 450 × 150 px | Clean, readable strokes |
| Simple logo or stamp | 150 to 250 px wide | Crisp, with slight edge softening |
| Face photo on a plain background | 100 × 120 to 150 × 180 px | Recognizable thumbnail |
| Busy photo | Under 120 px wide | Small and soft. Use a larger target if you can. |
These are estimates. The tool measures the actual result, and each card shows how close it came to the limit.
Getting a clean signature under 5 KB
- Sign with a dark pen on plain white paper. Lined or textured paper adds detail the file has to store.
- Photograph or scan in even light. Shadows and gray paper tones cost bytes and make the ink look faint.
- Crop tightly around the signature before compressing. Empty margins still take space.
- Turn on Black and white. Color data is removed, leaving more room for the pen strokes.
- Choose "Sharpness." It keeps the strokes crisp by making the image a bit smaller instead of letting blocky artifacts creep in.
The three settings, at this size
Balanced keeps quality at about 40% or higher and shrinks the image only as far as needed. Sharpness keeps quality near 70% and makes the image smaller, which is best for text and signatures. Dimensions keeps the width and height and lowers quality as far as needed, which can look blocky at 5 KB but satisfies forms that check pixel size. If a fixed pixel size simply can't fit, the card says so, and you can try smaller dimensions or a larger target.
Frequently asked questions
Can a normal photo really be compressed to 5 KB?
Yes, but it becomes a small thumbnail, around 120 to 180 pixels wide for a face on a plain background. If the form allows it, 20 KB or more gives a much better photo.
Are my signature and photos uploaded anywhere?
No. All processing happens in your browser, and nothing is sent to a server. You can disconnect from the internet after the page loads and the tool still works.
The form says "maximum 5 KB." Which KB setting should I use?
Leave it at 1,000 bytes. The file then stays under 5,000 bytes, which passes whether the form counts 1,000 or 1,024 bytes per KB.
Why does the tool say it can't reach 5 KB?
That happens when you set a fixed pixel size that's too large to fit in 5 KB even at the lowest quality. Lower the width and height, or raise the target.
Can the output be PNG instead of JPG?
This tool always makes a JPG, because it can hit exact size targets and nearly every form accepts it. A simple black-and-white signature can sometimes be smaller as a PNG, but PNG size can't be tuned to a target the same way.
Does it remove metadata?
Yes. The image is rebuilt from its pixels, so camera information and location data are dropped, and none of the 5 KB is wasted on them.