How Many Pixels Fit Under 20 KB, 50 KB, 100 KB or 1 MB?
Updated 11 November 2026 · Metro Research editorial team · How we test
Upload forms state a limit in kilobytes, but you control pixels, format and quality. To stop guessing, we measured how many bytes each pixel of a real photograph costs, then converted that into dimensions you can use.
The short answer
| Size limit | JPG q75 · typical | JPG q75 · safe start | JPG q85 · typical | WebP q75 · typical |
|---|---|---|---|---|
| 20 KB | 450 × 300 | 410 × 270 | 380 × 250 | 540 × 360 |
| 50 KB | 710 × 470 | 650 × 430 | 610 × 400 | 860 × 570 |
| 100 KB | 1010 × 670 | 920 × 610 | 860 × 570 | 1220 × 810 |
| 200 KB | 1430 × 950 | 1310 × 870 | 1220 × 810 | 1730 × 1150 |
| 500 KB | 2260 × 1500 | 2070 × 1380 | 1930 × 1290 | 2730 × 1820 |
| 1 MB | 3200 × 2130 | 2930 × 1950 | 2730 × 1820 | 3870 × 2580 |
“Typical” uses the average of our test photos; the “safe start” column uses the most detailed photo, so most images will fit at that size or larger. Busy scenes such as foliage, crowds or gravel sit near the safe column; plain backgrounds, skies and studio portraits compress much better.
How we measured it
We encoded four public-domain test photographs (a portrait, food, an animal and an outdoor scene) at several quality settings using standard JPEG, WebP and PNG encoders, and divided each file size by the number of pixels. The result is bits per pixel (bpp):
| Format and quality | Lowest | Average | Highest |
|---|---|---|---|
| JPG quality 95 | 2.17 | 2.91 | 3.49 |
| JPG quality 85 | 1.23 | 1.60 | 1.89 |
| JPG quality 75 | 0.84 | 1.17 | 1.39 |
| JPG quality 60 | 0.62 | 0.89 | 1.04 |
| WebP quality 85 | 0.86 | 1.23 | 1.59 |
| WebP quality 75 | 0.56 | 0.80 | 1.04 |
| PNG (lossless) | 8.85 | 12.35 | 14.73 |
To estimate the pixels that fit, use: pixels ≈ limit in bytes × 8 ÷ bpp. For a 100,000-byte limit at JPG quality 75 (1.17 bpp): 100,000 × 8 ÷ 1.17 ≈ 684,000 pixels, or about 1010 × 670 in a 3:2 frame.
What the numbers tell you
- PNG is the wrong format for photos. At around 12 bits per pixel it was roughly ten times larger than a quality-75 JPG.
- WebP saved about 30% versus JPG at the same quality number (0.80 vs 1.17 bpp at quality 75). Use it where it is accepted.
- Quality 95 costs about 2.5× the bytes of quality 75 for a difference most people cannot see on a phone screen.
- Signatures are tiny. A 600 × 200 pixel signature on white measured about 7.7 KB as JPG and 3.6 KB as WebP, so a 20 KB limit is easy if you crop away blank paper.
Limits of this test
Four small photos are a sample, not a census. Large camera images usually compress better per pixel than small ones, and each browser's encoder differs slightly. That is why the File Studio always checks the real byte count of your own export instead of predicting it.
Frequently asked questions
Why does my 100 KB photo look worse than expected?+
It probably contains a lot of fine texture, which costs more bytes per pixel. Reduce dimensions a little rather than dropping quality below about 60.
Does this apply to screenshots?+
Not directly. Screenshots with flat colors behave differently and often stay small as PNG.
Written for the current Metro Research tools. Spot an error? See our quality and corrections policy.