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Compress an image to 350 KB
To get an image under 350 KB, PixelFit aims at 350,000 bytes or less, so forms counting 1 KB as 1000 or 1024 bytes both accept it. Estimated from our measured encodes, that is about 1,334 × 1,000 pixels for a 4:3 photo at quality 75, or 1,850 × 2,310 for a portrait.
Under 350 KB
JPG · under 350 KB (at most 350,000 bytes) · original pixel size · white background
PixelFit aims at 350,000 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 350 KB means in bytes
350 KB is 358,400 bytes when 1 KB = 1024 bytes (350 × 1024) and 350,000 bytes when a server counts 1 KB = 1000 bytes. The 8,400-byte gap matters only near the limit. PixelFit aims at 350,000 bytes or less and prints the exact byte count, so you can compare it with the form.
350 KB is 0.34 MB; 29 such files fit in 10 MB. Uncompressed, the 1,334 × 1,000 photo that fits here would need 3.82 MB of raw pixels, so JPEG at quality 75 packs it about 11 to 1.
Largest pixel size that fits 350 KB
The biggest image of each kind, in its own aspect ratio, that stays at or below 350,000 bytes.
| Image | JPG q60 | JPG q75 | JPG q90 | WebP q75 |
|---|---|---|---|---|
| Head-and-shoulders portrait | 2,249 × 2,808 | 1,850 × 2,310 | 1,298 × 1,621 | 2,845 × 3,553* |
| Outdoor landscape (12 MP phone photo) | 1,541 × 1,155 | 1,334 × 1,000 | 1,055 × 791 | 1,425 × 1,068 |
| Scanned typed document page | 1,958 × 2,460 | 1,601 × 2,011 | 1,118 × 1,404 | 2,486 × 3,123* |
| Handwritten letter with signature | 3,259 × 2,679* | 2,610 × 2,145 | 1,766 × 1,451 | 4,157 × 3,417* |
| Flat-colour graphic (flag) | 7,538 × 5,276* | 6,925 × 4,847* | 5,594 × 3,915* | over 9,561 × 6,692 |
A 12 MP phone photo at 350 KB
Our 12 MP landscape sample (4032 × 3024) is about 4.15 MB at quality 90, 12 times the 350 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 350 KB near 1,334 × 1,000 (1.3 MP, 11 % of the original pixels). Quality 60 allows 1,541 × 1,155; quality 90 needs 1,055 × 791.
JPEG quality for fixed pixel sizes under 350 KB
When a form fixes the pixels, only quality can move. Highest quality (of 100) that keeps each size at or under 350,000 bytes:
| Pixel size | Measured on | JPG | WebP |
|---|---|---|---|
| 1080 × 1080 (square social post) | landscape photo | quality 80 (341 KB) | quality 83 (339 KB) |
| 1200 × 1600 (3:4 portrait upload) | portrait photo | quality 90 (314 KB) | quality 93 (301 KB) |
| 1920 × 1080 (Full HD frame) | landscape photo | quality 49 (338 KB) | quality 47 (341 KB) |
| 1240 × 1754 (A4 page at 150 DPI) | scanned typed page | quality 84 (337 KB) | quality 91 (312 KB) |
| 2480 × 3508 (A4 page at 300 DPI) | scanned typed page | quality 31 (337 KB) | quality 70 (339 KB) |
| 3000 × 4000 (12 MP portrait frame) | portrait photo | quality 32 (338 KB) | quality 68 (341 KB) |
Measured JPEG files either side of 350 KB
Real encodes from our test set at quality 75: the largest file that stays under 350,000 bytes and the smallest that goes over.
| Image | Largest under 350 KB | Smallest over 350 KB |
|---|---|---|
| Head-and-shoulders portrait | 1601 × 2000: 268,967 B | 1922 × 2400: 374,872 B |
| Outdoor landscape (12 MP phone photo) | 1200 × 900: 284,926 B | 1600 × 1200: 498,311 B |
| Scanned typed document page | 1592 × 2000: 346,869 B | 1910 × 2400: 465,268 B |
| Handwritten letter with signature | 2400 × 1973: 298,321 B | 3000 × 2466: 455,963 B |
| Flat-colour graphic (flag) | 3000 × 2100: 115,604 B | none: every measured size fits |
JPG, WebP or PNG at 350 KB
At quality 75, WebP holds 1,425 × 1,068 of the landscape photo in 350 KB, JPG 1,334 × 1,000: 14 % more pixels. Portrait gain: 137 % (extrapolated). Typed page gain: 141 % (extrapolated). A moderate gain for the landscape photo at 350 KB, a large one for portraits and typed pages: 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 350 KB it holds a flat graphic of 5,922 × 4,145 (extrapolated) pixels but a photo of only 485 × 363, against 1,334 × 1,000 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.
Which uploads fit comfortably in 350 KB
3 of the 6 sizes above keep quality 75 or better under 350 KB (1080 × 1080, 1200 × 1600, 1240 × 1754). At 1,334 × 1,000, quality 90 costs 60 % more bytes than quality 75.
A typed page reaches 1,958 × 2,460 at quality 60 in 350 KB, about 210 DPI if it is an A4 sheet.
How to compress an image to 350 KB
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Open the tool above
It is preset to 350 KB (350,000 bytes or less), JPG output.
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Add your image
Drop, paste or pick it; a PNG, WebP or (where the browser opens it) HEIC file becomes a JPG under 350 KB.
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Pixel size: only if asked
On auto, a typical photo stops near 1,334 × 1,000 at about quality 75.
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Download and check
name-350kb.jpg comes with its byte count, pixels and quality.
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 350 KB?
Drop it into the tool here, preset to 350 KB. It searches JPEG quality (at most 8 encodes per pixel size), then scales pixels down if needed, until the file is 350,000 bytes or less. A 4:3 photo typically lands near 1,334 × 1,000 at about quality 75.
How do I compress an image to less than 350 KB without losing quality?
Give up pixels before quality: at quality 75, 350 KB holds 1,334 × 1,000 of a photo and 1,850 × 2,310 of a portrait; quality 90 at 1,334 × 1,000 costs 60 % more bytes.
Is 350 KB 350,000 or 358,400 bytes?
Both readings exist: 358,400 bytes (1 KB = 1024) or 350,000 bytes (1 KB = 1000). 350,000 bytes or less passes both.
Can I compress a PNG to 350 KB?
Yes, but a full-colour PNG photo stays big: about 485 × 363 pixels in 350 KB, versus 5,922 × 4,145 (extrapolated) for a flat graphic. As a JPG the photo reaches 1,334 × 1,000.
What pixel size fits 350 KB?
At quality 75: a photo 1,334 × 1,000, a portrait 1,850 × 2,310, a typed page 1,601 × 2,011.
Related
Nearby file sizes
- Compress to 300 KB photo ≈ 1,232 × 924
- Compress to 250 KB photo ≈ 1,128 × 846
- Compress to 240 KB photo ≈ 1,106 × 829
- Compress to 400 KB photo ≈ 1,429 × 1,071
- Compress to 500 KB photo ≈ 1,603 × 1,202
- Compress to 512 KB photo ≈ 1,623 × 1,217
More ways to hit 350 KB
- Image resizer with KB target Any size, pixels and format
Pixel sizes that fit 350 KB
- 1280×1024 (SXGA) about 336 KB as a quality-75 JPG
- 1440×900 about 332 KB as a quality-75 JPG
- 1280×960 landscape about 315 KB as a quality-75 JPG
- 1080×1080 square about 300 KB as a quality-75 JPG