Updated · how we check
Compress an image to 20 KB
To get an image under 20 KB, PixelFit aims at 20,000 bytes or less, so forms counting 1 KB as 1000 or 1024 bytes both accept it. Estimated from our measured encodes, that is about 317 × 237 pixels for a 4:3 photo at quality 75, or 304 × 379 for a portrait.
Under 20 KB
JPG · under 20 KB (at most 20,000 bytes) · original pixel size · white background
PixelFit aims at 20,000 bytes or less, so the file passes whether the form counts 1 KB as 1,000 or 1,024 bytes.
Fit, background and padding white background
Saving presets is part of Pro.
The result appears here: the exact byte count, pixel size and quality, the size before and after, a preview and a download button.
The batch kit (one ZIP for up to 500 photos, several photos merged into one PDF) is part of Pro.
What 20 KB means in bytes
20 KB is 20,480 bytes when 1 KB = 1024 bytes (20 × 1024) and 20,000 bytes when a server counts 1 KB = 1000 bytes. The 480-byte gap matters only near the limit. PixelFit aims at 20,000 bytes or less and prints the exact byte count, so you can compare it with the form.
20 KB is 0.020 MB; 512 such files fit in 10 MB. Uncompressed, the 317 × 237 photo that fits here would need 220 KB of raw pixels, so JPEG at quality 75 packs it about 11 to 1.
Largest pixel size that fits 20 KB
The biggest image of each kind, in its own aspect ratio, that stays at or below 20,000 bytes.
| Image | JPG q60 | JPG q75 | JPG q90 | WebP q75 |
|---|---|---|---|---|
| Head-and-shoulders portrait | 360 × 449 | 304 × 379 | 220 × 274 | 419 × 523 |
| Outdoor landscape (12 MP phone photo) | 370 × 277 | 317 × 237 | 245 × 183 | 341 × 255 |
| Scanned typed document page | 347 × 436 | 300 × 376 | 229 × 287 | 350 × 439 |
| Handwritten letter with signature | 641 × 526 | 531 × 436 | 371 × 305 | 822 × 675 |
| Flat-colour graphic (flag) | 918 × 642 | 770 × 539 | 556 × 389 | 1,236 × 865 |
A 12 MP phone photo at 20 KB
Our 12 MP landscape sample (4032 × 3024) is about 4.15 MB at quality 90, 218 times the 20 KB budget; even quality 30 leaves 1.26 MB (extrapolated from encodes up to 3,000 px). So the pixels must go down too.
At about quality 75 it fits 20 KB near 317 × 237 (0.08 MP, 0.62 % of the original pixels). Quality 60 allows 370 × 277; quality 90 needs 245 × 183.
JPEG quality for fixed pixel sizes under 20 KB
When a form fixes the pixels, only quality can move. Highest quality (of 100) that keeps each size at or under 20,000 bytes:
| Pixel size | Measured on | JPG | WebP |
|---|---|---|---|
| 300 × 120 (signature strip) | handwritten page | quality 95+ (10.1 KB) | quality 95+ (6.8 KB) |
| 200 × 230 (small ID photo) | portrait photo | quality 93 (19.3 KB) | quality 95+ (17.4 KB) |
| 413 × 531 (35 × 45 mm at 300 DPI) | portrait photo | quality 42 (19.4 KB) | quality 75 (19.5 KB) |
| 600 × 600 (2 × 2 inch at 300 DPI) | portrait photo | no: fewer pixels needed | quality 48 (19.3 KB) |
| 800 × 600 (4:3 web photo) | landscape photo | no: fewer pixels needed | no: fewer pixels needed |
| 1200 × 1600 (3:4 portrait upload) | portrait photo | no: fewer pixels needed | no: fewer pixels needed |
Measured JPEG files either side of 20 KB
Real encodes from our test set at quality 75: the largest file that stays under 20,000 bytes and the smallest that goes over.
| Image | Largest under 20 KB | Smallest over 20 KB |
|---|---|---|
| Head-and-shoulders portrait | 240 × 300: 14,229 B | 320 × 400: 21,568 B |
| Outdoor landscape (12 MP phone photo) | 300 × 225: 18,059 B | 400 × 300: 30,893 B |
| Scanned typed document page | 239 × 300: 12,810 B | 318 × 400: 22,368 B |
| Handwritten letter with signature | 500 × 411: 18,061 B | 600 × 493: 24,480 B |
| Flat-colour graphic (flag) | 600 × 420: 14,688 B | 800 × 560: 20,958 B |
JPG, WebP or PNG at 20 KB
At quality 75, WebP holds 341 × 255 of the landscape photo in 20 KB, JPG 317 × 237: 16 % more pixels. Portrait gain: 90 %. Typed page gain: 36 %. A moderate gain for the landscape photo at 20 KB, a large one for portraits: where WebP is accepted, use it for those. Many portals accept only JPG/JPEG, so this page starts in JPG.
A full-colour PNG is lossless, so its size follows the content. In 20 KB it holds a flat graphic of 484 × 338 pixels but a photo of only 112 × 84, against 317 × 237 as a quality-75 JPG. Reducing a PNG to a palette of up to 256 colours (PixelFit does this when a PNG must shrink) helps graphics far more than photos.
Signatures and thumbnails under 20 KB
In our form dataset, 14 photo or signature limits are 20 KB or less: 12 for signatures, 2 for photos. Measured for 20 KB:
- A handwritten page fits at 531 × 436 at quality 75, so a cropped signature strip has room to spare.
- A typed page fits at 347 × 436 at quality 60: crop to the lines the form needs.
- A portrait fits at 304 × 379 at quality 75, a stamp-size photo.
- Cropping empty paper first leaves more of the 20,000 bytes for the strokes or the face.
How to compress an image to 20 KB
-
Open the tool above
It is preset to 20 KB (20,000 bytes or less), JPG output.
-
Add your image
Drop, paste or pick it; a PNG, WebP or (where the browser opens it) HEIC file becomes a JPG under 20 KB.
-
Pixel size: only if asked
On auto, a typical photo stops near 317 × 237 at about quality 75.
-
Download and check
name-20kb.jpg comes with its byte count, pixels and quality.
Forms that ask for 20 KB
Upload specs in our dataset with exactly 20 KB. Verify with the official notice before you submit.
Sources
- Measured by PixelFit with sharp 0.35.5 / libvips 8.18.7 on 31 October 2026.
- Sample images, Wikimedia Commons, checked 31 October 2026: landscape (CC0 1.0) commons.wikimedia.org/w/index.php?curid=154070378; portrait commons.wikimedia.org/w/index.php?curid=23956389; typed page commons.wikimedia.org/w/index.php?curid=194775753; handwritten letter commons.wikimedia.org/w/index.php?curid=90423615; flag commons.wikimedia.org/w/index.php?curid=361734 (public domain).
- Binary prefixes, NIST, checked 31 October 2026: physics.nist.gov/cuu/Units/binary.html
Frequently asked questions
How do I compress an image to 20 KB?
Drop it into the tool here, preset to 20 KB. It searches JPEG quality (at most 8 encodes per pixel size), then scales pixels down if needed, until the file is 20,000 bytes or less. A 4:3 photo typically lands near 317 × 237 at about quality 75.
How do I compress an image to less than 20 KB without losing quality?
Give up pixels before quality: at quality 75, 20 KB holds 317 × 237 of a photo and 304 × 379 of a portrait; quality 90 at 317 × 237 costs 63 % more bytes.
Is 20 KB 20,000 or 20,480 bytes?
Both readings exist: 20,480 bytes (1 KB = 1024) or 20,000 bytes (1 KB = 1000). 20,000 bytes or less passes both.
Can I compress a PNG to 20 KB?
Yes, but a full-colour PNG photo stays big: about 112 × 84 pixels in 20 KB, versus 484 × 338 for a flat graphic. As a JPG the photo reaches 317 × 237.
Why does my signature look blurry at 20 KB?
Usually the scan is huge and gets scaled down hard. Crop tightly first: a handwritten page fits 20 KB at 531 × 436 at quality 75.
Related
Nearby file sizes
- Compress to 16 KB photo ≈ 282 × 211
- Compress to 15 KB photo ≈ 273 × 204
- Compress to 12 KB photo ≈ 243 × 182
- Compress to 25 KB photo ≈ 357 × 267
- Compress to 30 KB photo ≈ 394 × 295
- Compress to 35 KB photo ≈ 426 × 319
More ways to hit 20 KB
- JPG to PDF under 20 KB One image as a PDF
- Between 10 KB and 20 KB Minimum and maximum
- Between 20 KB and 50 KB Minimum and maximum
- Between 20 KB and 100 KB Minimum and maximum
- Between 20 KB and 300 KB Minimum and maximum
- Image resizer with KB target Any size, pixels and format
Pixel sizes that fit 20 KB
- 300×250 banner about 19.5 KB as a quality-75 JPG
- 120×600 banner about 18.7 KB as a quality-75 JPG
- 256×256 icon about 17.1 KB as a quality-75 JPG
- 728×90 banner about 17.1 KB as a quality-75 JPG