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Compress an image to 45 KB
To get an image under 45 KB, PixelFit aims at 45,000 bytes or less, so forms counting 1 KB as 1000 or 1024 bytes both accept it. Estimated from our measured encodes, that is about 483 × 362 pixels for a 4:3 photo at quality 75, or 525 × 655 for a portrait.
Under 45 KB
JPG · under 45 KB (at most 45,000 bytes) · original pixel size · white background
PixelFit aims at 45,000 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 45 KB means in bytes
45 KB is 46,080 bytes when 1 KB = 1024 bytes (45 × 1024) and 45,000 bytes when a server counts 1 KB = 1000 bytes. The 1,080-byte gap matters only near the limit. PixelFit aims at 45,000 bytes or less and prints the exact byte count, so you can compare it with the form.
45 KB is 0.044 MB; 227 such files fit in 10 MB. Uncompressed, the 483 × 362 photo that fits here would need 512 KB of raw pixels, so JPEG at quality 75 packs it about 12 to 1.
Largest pixel size that fits 45 KB
The biggest image of each kind, in its own aspect ratio, that stays at or below 45,000 bytes.
| Image | JPG q60 | JPG q75 | JPG q90 | WebP q75 |
|---|---|---|---|---|
| Head-and-shoulders portrait | 622 × 776 | 525 × 655 | 380 × 474 | 794 × 991 |
| Outdoor landscape (12 MP phone photo) | 558 × 418 | 483 × 362 | 375 × 281 | 513 × 384 |
| Scanned typed document page | 533 × 669 | 458 × 575 | 351 × 441 | 561 × 704 |
| Handwritten letter with signature | 1,044 × 858 | 855 × 702 | 589 × 484 | 1,361 × 1,118 |
| Flat-colour graphic (flag) | 1,711 × 1,197 | 1,471 × 1,029 | 1,081 × 756 | 2,522 × 1,765 |
A 12 MP phone photo at 45 KB
Our 12 MP landscape sample (4032 × 3024) is about 4.15 MB at quality 90, 97 times the 45 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 45 KB near 483 × 362 (0.17 MP, 1 % of the original pixels). Quality 60 allows 558 × 418; quality 90 needs 375 × 281.
JPEG quality for fixed pixel sizes under 45 KB
When a form fixes the pixels, only quality can move. Highest quality (of 100) that keeps each size at or under 45,000 bytes:
| Pixel size | Measured on | JPG | WebP |
|---|---|---|---|
| 200 × 230 (small ID photo) | portrait photo | quality 95+ (21.9 KB) | quality 95+ (17.4 KB) |
| 413 × 531 (35 × 45 mm at 300 DPI) | portrait photo | quality 86 (43 KB) | quality 92 (42.6 KB) |
| 600 × 600 (2 × 2 inch at 300 DPI) | portrait photo | quality 73 (43.8 KB) | quality 87 (43.9 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 |
| 1240 × 1754 (A4 page at 150 DPI) | scanned typed page | no: fewer pixels needed | no: fewer pixels needed |
Measured JPEG files either side of 45 KB
Real encodes from our test set at quality 75: the largest file that stays under 45,000 bytes and the smallest that goes over.
| Image | Largest under 45 KB | Smallest over 45 KB |
|---|---|---|
| Head-and-shoulders portrait | 480 × 600: 39,317 B | 641 × 800: 60,900 B |
| Outdoor landscape (12 MP phone photo) | 400 × 300: 30,893 B | 500 × 375: 48,064 B |
| Scanned typed document page | 398 × 500: 34,663 B | 477 × 600: 48,445 B |
| Handwritten letter with signature | 800 × 658: 39,979 B | 1000 × 822: 59,731 B |
| Flat-colour graphic (flag) | 1200 × 840: 34,937 B | 1600 × 1120: 49,963 B |
JPG, WebP or PNG at 45 KB
At quality 75, WebP holds 513 × 384 of the landscape photo in 45 KB, JPG 483 × 362: 13 % more pixels. Portrait gain: 129 %. Typed page gain: 50 %. A moderate gain for the landscape photo at 45 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 45 KB it holds a flat graphic of 969 × 678 pixels but a photo of only 171 × 128, against 483 × 362 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 45 KB
2 of the 6 sizes above keep quality 75 or better under 45 KB (200 × 230, 413 × 531); 3 miss even at quality 30 (800 × 600, 1200 × 1600, 1240 × 1754). At 483 × 362, quality 90 costs 64 % more bytes than quality 75.
A typed page reaches 533 × 669 at quality 60 in 45 KB, about 57 DPI if it is an A4 sheet.
How to compress an image to 45 KB
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Open the tool above
It is preset to 45 KB (45,000 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 45 KB.
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Pixel size: only if asked
On auto, a typical photo stops near 483 × 362 at about quality 75.
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Download and check
name-45kb.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 45 KB?
Drop it into the tool here, preset to 45 KB. It searches JPEG quality (at most 8 encodes per pixel size), then scales pixels down if needed, until the file is 45,000 bytes or less. A 4:3 photo typically lands near 483 × 362 at about quality 75.
How do I compress an image to less than 45 KB without losing quality?
Give up pixels before quality: at quality 75, 45 KB holds 483 × 362 of a photo and 525 × 655 of a portrait; quality 90 at 483 × 362 costs 64 % more bytes.
Is 45 KB 45,000 or 46,080 bytes?
Both readings exist: 46,080 bytes (1 KB = 1024) or 45,000 bytes (1 KB = 1000). 45,000 bytes or less passes both.
Can I compress a PNG to 45 KB?
Yes, but a full-colour PNG photo stays big: about 171 × 128 pixels in 45 KB, versus 969 × 678 for a flat graphic. As a JPG the photo reaches 483 × 362.
What pixel size fits 45 KB?
At quality 75: a photo 483 × 362, a portrait 525 × 655, a typed page 458 × 575.
Related
Nearby file sizes
- Compress to 40 KB photo ≈ 455 × 341
- Compress to 35 KB photo ≈ 426 × 319
- Compress to 30 KB photo ≈ 394 × 295
- Compress to 50 KB photo ≈ 510 × 382
- Compress to 60 KB photo ≈ 557 × 417
- Compress to 70 KB photo ≈ 600 × 450
More ways to hit 45 KB
- Image resizer with KB target Any size, pixels and format
Pixel sizes that fit 45 KB
- 35×35 mm photo about 42.7 KB as a quality-75 JPG
- 30×40 mm photo about 41.9 KB as a quality-75 JPG
- 400×400 square about 40.1 KB as a quality-75 JPG
- 25×35 mm photo about 30.6 KB as a quality-75 JPG