How to make a PNG file smaller: 5 fixes, measured

Why is my PNG file so large?

A PNG is large because it keeps every pixel exactly, and a photo has millions of them. Our 2,427 × 3,640 flower photo held 110,536 different colours. Saved as a PNG, it came to 21.4 MB. The same photo as a JPG was 1.4 MB.

PNG is lossless: it never throws a pixel away, so it can only shrink what repeats. A screenshot repeats a lot, with flat white and a few text colours. A photo hardly repeats at all. So three things make a PNG big: many pixels, many colours, and a save that did not try hard.

How to make a PNG file smaller: 5 fixes, measured

We ran every fix on three PNGs that tend to come out large: a photo, a screenshot at Retina size and a photo cut out on a see-through background. Here is what each fix did, with how far the pixels moved in dB (higher is closer; in our crops, the 40 dB files were hard to tell from the source).

1. Re-save it losslessly

A lossless re-save packs the same pixels tighter, and changes nothing you can see. Our photo went from 21.4 MB to 16.2 MB, 24% smaller. The cutout lost 34%. The screenshot, already tight, lost 5%. Safe, but rarely enough.

2. Cut it to 256 colours

This is the fix that moves the most, and the one most PNG compressors use. The file keeps a palette of 256 colours and maps every pixel to the nearest one. The screenshot went from 290.9 KB to 62.4 KB at 49.5 dB. The photo went to 6.5 MB at 41 dB, and it is still a PNG. A cutout keeps its transparency at 256 colours too.

3. Make it fewer pixels

Half the width and height is a quarter of the pixels. At 256 colours, the photo at 1,214 × 1,821 came to 1.5 MB. Shrink it to the size it will be shown at, not smaller; the PNG resizer keeps it a PNG.

4. Convert a photo to JPG, WebP or AVIF

When the picture is a photo with no transparency, PNG is the wrong format. The flower photo was 1.4 MB as a JPG, 1.7 MB as WebP and 857.3 KB as AVIF. That is 15 times smaller than the PNG for the JPG alone.

A screenshot is the opposite case. As a JPG it came to 87.6 KB, bigger than the 62.4 KB 256-colour PNG, and blurrier at the letters. Keep screenshots as PNG; the PNG vs JPG guide covers the rest of that choice.

5. Keep transparency in WebP or AVIF

A cutout cannot become a JPG, because JPG has no transparency. WebP and AVIF keep it. Our cutout was 3.5 MB as a PNG, 147.0 KB as WebP and 88.7 KB as AVIF, with the soft edge intact. Use the PNG to WebP converter when the place it goes accepts WebP.

Which fix to use for your PNG

How to reduce PNG file size without losing quality

Without losing a single pixel, two fixes work: a lossless re-save, and lossless WebP if the file may change format. Lossless WebP made our photo 9.9 MB and the screenshot 156.9 KB, every pixel identical. For anything smaller, 256 colours is the change you are least likely to see.

How to make a PNG smaller in Photoshop, on a Mac and in Windows

• Photoshop: choose Image, Mode, Indexed Color to cut the colours, then File, Save As, and PNG. Pick None for Interlace: interlacing “increases file size”, Adobe’s help page says.
• Mac: Preview has no PNG compression setting. Choose Tools, then Adjust Size, to make it fewer pixels, Apple’s Preview guide shows.
• Windows: Paint can also only resize. Open the PNG, press Ctrl+W, choose Pixels and a smaller width, then save.
• Any browser: drop it into the PNG compressor. It cuts the file to 256 colours and re-saves it, and keeps the transparency.

Need it under a set size, such as 100 KB for a form? Set Max file size, and the engine finds the quality that fits; the 100 KB compressor opens on it.

How we tested

• The PNGs: trnghieuphotos’s flower photo from Pixabay, saved as a PNG at 2,427 × 3,640; a screenshot of a settings card we drew at 2,400 × 1,260; and nataraj_07’s leaf from Pixabay, cut into a soft oval on a see-through background at 1,200 × 2,133.
• The fixes: Blinkimg’s engine, version 9, made every file but lossless WebP, which sharp 0.35.4 made; measured 2026-10-14.
• The score: PSNR against the PNG as saved, in dB. For the cutout, each colour is weighted by how visible it is, so a hidden colour under a clear pixel does not count. How we measure covers the rest.