Updated · how we check
Compress an image to 512 KB
To get an image under 512 KB, PixelFit aims at 512,000 bytes or less, so forms counting 1 KB as 1000 or 1024 bytes both accept it. Estimated from our measured encodes, that is about 1,623 × 1,217 pixels for a 4:3 photo at quality 75, or 2,265 × 2,828 for a portrait.
Under 512 KB
JPG · under 512 KB (at most 512,000 bytes) · original pixel size · white background
PixelFit aims at 512,000 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 512 KB means in bytes
512 KB is 524,288 bytes when 1 KB = 1024 bytes (512 × 1024) and 512,000 bytes when a server counts 1 KB = 1000 bytes. The 12,288-byte gap matters only near the limit. PixelFit aims at 512,000 bytes or less and prints the exact byte count, so you can compare it with the form.
512 KB is exactly half a megabyte of 1,048,576 bytes (524,288 bytes). A form that writes the same limit as "0.5 MB" may count 500,000 bytes instead, which the 512,000-byte target here would overshoot; for that wording use the 500 KB target (at most 500,000 bytes), which passes every reading.
Largest pixel size that fits 512 KB
The biggest image of each kind, in its own aspect ratio, that stays at or below 512,000 bytes.
| Image | JPG q60 | JPG q75 | JPG q90 | WebP q75 |
|---|---|---|---|---|
| Head-and-shoulders portrait | 2,773 × 3,463* | 2,265 × 2,828 | 1,583 × 1,977 | 3,521 × 4,397* |
| Outdoor landscape (12 MP phone photo) | 1,877 × 1,407 | 1,623 × 1,217 | 1,274 × 955 | 1,742 × 1,306 |
| Scanned typed document page | 2,489 × 3,127* | 2,027 × 2,547 | 1,406 × 1,766 | 3,287 × 4,130* |
| Handwritten letter with signature | 3,987 × 3,277* | 3,188 × 2,620* | 2,133 × 1,753 | 5,081 × 4,177* |
| Flat-colour graphic (flag) | over 9,561 × 6,692 | 9,229 × 6,460* | 7,602 × 5,321* | over 9,561 × 6,692 |
A 12 MP phone photo at 512 KB
Our 12 MP landscape sample (4032 × 3024) is about 4.15 MB at quality 90, 9 times the 512 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 512 KB near 1,623 × 1,217 (2 MP, 16 % of the original pixels). Quality 60 allows 1,877 × 1,407; quality 90 needs 1,274 × 955.
JPEG quality for fixed pixel sizes under 512 KB
When a form fixes the pixels, only quality can move. Highest quality (of 100) that keeps each size at or under 512,000 bytes:
| Pixel size | Measured on | JPG | WebP |
|---|---|---|---|
| 1080 × 1080 (square social post) | landscape photo | quality 90 (480 KB) | quality 92 (497 KB) |
| 1200 × 1600 (3:4 portrait upload) | portrait photo | quality 95+ (486 KB) | quality 95+ (393 KB) |
| 1920 × 1080 (Full HD frame) | landscape photo | quality 72 (494 KB) | quality 78 (499 KB) |
| 1240 × 1754 (A4 page at 150 DPI) | scanned typed page | quality 91 (481 KB) | quality 95+ (471 KB) |
| 2480 × 3508 (A4 page at 300 DPI) | scanned typed page | quality 54 (495 KB) | quality 81 (489 KB) |
| 3000 × 4000 (12 MP portrait frame) | portrait photo | quality 49 (492 KB) | quality 78 (479 KB) |
Measured JPEG files either side of 512 KB
Real encodes from our test set at quality 75: the largest file that stays under 512,000 bytes and the smallest that goes over.
| Image | Largest under 512 KB | Smallest over 512 KB |
|---|---|---|
| Head-and-shoulders portrait | 1922 × 2400: 374,872 B | 2402 × 3000: 571,851 B |
| Outdoor landscape (12 MP phone photo) | 1600 × 1200: 498,311 B | 2000 × 1500: 762,196 B |
| Scanned typed document page | 1910 × 2400: 465,268 B | 2387 × 3000: 666,088 B |
| Handwritten letter with signature | 3000 × 2466: 455,963 B | none: every measured size fits |
| Flat-colour graphic (flag) | 3000 × 2100: 115,604 B | none: every measured size fits |
JPG, WebP or PNG at 512 KB
At quality 75, WebP holds 1,742 × 1,306 of the landscape photo in 512 KB, JPG 1,623 × 1,217: 15 % more pixels. Portrait gain: 142 % (extrapolated). Typed page gain: 163 % (extrapolated). A moderate gain for the landscape photo at 512 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 512 KB it holds a flat graphic of 8,241 × 5,768 (extrapolated) pixels but a photo of only 586 × 439, against 1,623 × 1,217 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 512 KB
3 of the 6 sizes above keep quality 75 or better under 512 KB (1080 × 1080, 1200 × 1600, 1240 × 1754). At 1,623 × 1,217, quality 90 costs 60 % more bytes than quality 75.
A typed page reaches 2,489 × 3,127 (extrapolated) at quality 60 in 512 KB, about 267 DPI if it is an A4 sheet.
How to compress an image to 512 KB
-
Open the tool above
It is preset to 512 KB (512,000 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 512 KB.
-
Pixel size: only if asked
On auto, a typical photo stops near 1,623 × 1,217 at about quality 75.
-
Download and check
name-512kb.jpg comes with its byte count, pixels and quality.
Forms that ask for 512 KB
Upload specs in our dataset with exactly 512 KB. Verify with the official notice before you submit.
512 KB limits
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 512 KB?
Drop it into the tool here, preset to 512 KB. It searches JPEG quality (at most 8 encodes per pixel size), then scales pixels down if needed, until the file is 512,000 bytes or less. A 4:3 photo typically lands near 1,623 × 1,217 at about quality 75.
How do I compress an image to less than 512 KB without losing quality?
Give up pixels before quality: at quality 75, 512 KB holds 1,623 × 1,217 of a photo and 2,265 × 2,828 of a portrait; quality 90 at 1,623 × 1,217 costs 60 % more bytes.
Is 512 KB 512,000 or 524,288 bytes?
Both readings exist: 524,288 bytes (1 KB = 1024) or 512,000 bytes (1 KB = 1000). 512,000 bytes or less passes both.
Can I compress a PNG to 512 KB?
Yes, but a full-colour PNG photo stays big: about 586 × 439 pixels in 512 KB, versus 8,241 × 5,768 (extrapolated) for a flat graphic. As a JPG the photo reaches 1,623 × 1,217.
What pixel size fits 512 KB?
At quality 75: a photo 1,623 × 1,217, a portrait 2,265 × 2,828, a typed page 2,027 × 2,547.
Related
Nearby file sizes
- Compress to 500 KB photo ≈ 1,603 × 1,202
- Compress to 400 KB photo ≈ 1,429 × 1,071
- Compress to 350 KB photo ≈ 1,334 × 1,000
- Compress to 600 KB photo ≈ 1,763 × 1,322
- Compress to 700 KB photo ≈ 1,913 × 1,434
- Compress to 800 KB photo ≈ 2,054 × 1,540
More ways to hit 512 KB
- Compress to 500 KB For limits written as 0.5 MB
- Image resizer with KB target Any size, pixels and format
Pixel sizes that fit 512 KB
- 1600×1200 (UXGA) about 487 KB as a quality-75 JPG
- 1200×1600 portrait about 487 KB as a quality-75 JPG
- 1200×1500 portrait about 457 KB as a quality-75 JPG
- 1680×1050 (WSXGA+) about 448 KB as a quality-75 JPG