Compress Image to 15KB — Free, Fast & Private
A band like 10–20 KB has two ways to fail and one way to pass. Most people aim at the ceiling, land a hair under it, and then meet a portal that rounds differently from their computer. Aiming at 15 KB gives you 5 KB of room below and 5 KB above, which is the whole reason this page exists.
What fits in 15 KB — measured on this page
We dropped five real files on the compressor above and kept what it handed back. 5 of 5 came out under 15 KB; 3 were made smaller in pixels to get there, because past a point the bytes can only come from pixels.
| File | Before | After, on this page | Under 15 KB? |
|---|---|---|---|
| 12 MP phone photo | 4032 × 3024 px · 3.73 MB | 1107 × 830 px · 14.5 KB | Yes |
| Portrait / headshot | 3264 × 4653 px · 2.25 MB | 1284 × 1830 px · 13.1 KB | Yes |
| Scanned handwritten page | 3349 × 4281 px · 2.17 MB | 1185 × 1515 px · 13.0 KB | Yes |
| Scanned signature | 2041 × 617 px · 109.1 KB | 2041 × 617 px · 14.5 KB | Yes |
| Screenshot (PNG) | 1280 × 800 px · 88.1 KB | 1280 × 800 px · 13.3 KB | Yes |
Measured 2026-10-06 in Chromium 145.0.7632.6 with this page’s own settings. The photos are public-domain and CC0 files from Wikimedia Commons; the screenshot is our own. Sizes read as the tool shows them (1 KB = 1,024 bytes); the target itself is 15,000 bytes, which is under 15 KB on either reading.
The forms that share a 10–20 KB band
The three biggest recruitment portals for clerical, officer and staff posts print the same signature range in their own 2026 notifications. The transport ministry's Sarathi portal asks for a driving-licence photo inside the same numbers. Two neighbouring forms are listed so you can see where this band stops.
| Upload | Band | Pixels named |
|---|---|---|
| SSC signature (CGL, CHSL, GD, MTS) | 10–20 KB | print size about 6 × 2 cm |
| IBPS PO / Clerk signature | 10–20 KB | 140 × 60 px (preferred) |
| SBI PO / Clerk signature | 10–20 KB | 140 × 60 px (preferred) |
| Driving licence photo (Sarathi) | 10–20 KB | 420 × 525 px |
| CTET signature, for contrast | 3–30 KB | 3.5 × 1.5 cm |
| RRB signature, for contrast | 30–49 KB | at least 140 × 60 px |
CTET would take a 15 KB signature too, since it sits inside 3–30 KB. RRB would not: its band starts at 30 KB, so a railway form needs a bigger file — the RRB signature tool aims there. Nothing here says a portal will accept your file; it tells you what the file will measure, which is the part you control.
Why the middle survives both ways of counting a kilobyte
This page’s target counts a kilobyte as 1,000 bytes. Some upload checks count 1,024. The two conventions move a band’s edges: 10 KB is 10,000 bytes one way and 10,240 the other; 20 KB is 20,000 or 20,480. A file sitting at either edge can pass under one reading and fail under the other.
A file of at most 15,000 bytes clears 10,240 and stays under 20,000 — inside the band whichever way the portal counts, as long as the compressor did not have to go far below the target. That last condition matters, and the next section is about it.
When a signature comes out under the floor
The 15,000-byte target is a ceiling. The tool compresses until the file fits and never pads it upwards, so a file that already fits can come out well below 15 KB — and below 10 KB is a rejection just as surely as above 20. A form with a far smaller cap needs a different rung, such as the 5 KB target.
The arithmetic shows why a signature is the case to watch. IBPS and SBI prefer 140 × 60 pixels, which is 8,400 pixels. Stored raw at three bytes a pixel that is 25,200 bytes, so a 15,000-byte budget allows 1.79 bytes for every pixel — more than half of the raw size. JPEG exists to come in far under raw, and dark ink on white paper is mostly flat white, so at the preferred size the file can easily land beneath the floor.
If that happens, raise the JPEG quality, or keep more pixels where the form allows it (IBPS and SBI call 140 × 60 preferred, not mandatory; SSC states a print size instead). Do not enlarge a tiny crop by stretching it — that adds bytes by adding blur.
Checking the number before you upload
Two different “KB” figures can describe the same file, and it helps to know why before a mismatch sends you back to compress again. The target on this page uses 1,000-byte kilobytes. The size the tool prints beside your result — and the measured table above, which shows each file exactly as the tool did — divides by 1,024 instead, the convention Windows Explorer also uses, so a file at the full 15,000-byte target reads in the tool as 14.6 KB. macOS Finder divides by 1,000. Windows’ Properties dialog also shows a “size on disk”, rounded up to the drive’s storage blocks; ignore that line, because a portal reads the file, not the disk.
The safest check is the byte count itself. A file of 15,000 bytes or fewer, and more than 10,240 bytes, sits inside 10–20 KB under either convention. If the portal’s error message quotes a number, compare bytes to bytes rather than trusting two rounded KB figures.
The driving-licence photo is the opposite problem
Sarathi asks for a photo of 420 × 525 pixels in 10–20 KB. That is 220,500 pixels, so 15,000 bytes leaves 0.07 bytes per pixel — about one 44th of raw. Here the danger is the ceiling, not the floor: a face has far more detail than a signature, and the tool has to work for it.
It works in a fixed order. First it lowers JPEG quality at the full 420-pixel width, looking for the highest quality that fits. Only if even the lowest quality misses does it reduce the dimensions — and then it tells you and shows the new size, which would no longer match Sarathi’s stated pixels. Check the measured table near the top of this page for what happened to each sample, and if your photo is resized, crop tighter to the head and shoulders and try again rather than accepting a smaller image. The passport photo maker can set up the frame first.
Everything runs in your browser. Your signature and your photo are never uploaded, so nothing that could be used to impersonate you passes through anyone else’s server. For per-exam signature detail, see the signature guide.
Forms that ask for a window rather than a ceiling are covered on between 10KB and 20KB.