The Thing You'll Double-Check When You Read It
Right-click your last long scrolling screenshot. Check the size.
There's a non-trivial chance the answer is "more than 20 MB." There's a real chance it's over 50 MB.
Now check a 60-second 1080p video clip on your phone. Almost certainly less than 20 MB. Sometimes less than 10.
How is a still image bigger than a minute of moving pictures? This is one of those weird facts about digital files that nobody tells you until you hit the "file too large" error on Slack for the fifth time today.
Here's what's actually happening — and why converting your screenshots fixes it instantly.
Why PNG Screenshots Are Massive
PNG is a lossless format. That is the entire problem.
When you take a screenshot, macOS, Windows, and most Android phones default to PNG. Every pixel of your screen is recorded exactly as it appears — no approximation, no "close enough." For screenshots of text, icons, and UI elements, this is genuinely useful. Lossless means the 1-pixel-wide border on a button stays crisp; the anti-aliasing on text stays sharp.
But lossless compression only gets you so far. PNG's best trick is recognizing repeated patterns — a big block of white background compresses well because it's literally the same pixel over and over. The moment your screenshot includes a photo, a gradient, a shadow, or anti-aliased text on a textured background, PNG's compression falls apart and the file balloons.
A full-page screenshot of a long article? Every subtle gradient in every image, every shadow, every gradient on every card, every pixel of anti-aliasing on every letter of body text — all preserved exactly, all bloating your file.
Result: a screenshot that should conceptually be "a picture of some text" ends up 30 MB.
Why Video Is Smaller
Video seems like it should be bigger. It has hundreds of frames per second. Each frame is its own picture. Add audio. Add motion.
The trick: video codecs don't store every frame. They store the *differences* between frames — and they're allowed to be "close enough" instead of exact.
H.264, the codec your phone uses for everything, essentially says:
It's lossy compression on top of temporal compression. The math is absurdly efficient. A minute of 1080p video at a reasonable bitrate fits in 10 MB because 99% of what you're seeing is redundant between frames, and the codec is exploiting every bit of that redundancy.
PNG can't do any of this. It has one frame. It has to preserve every pixel. It loses.
The 10-Second Fix
You don't need PNG's pixel-perfect preservation for the vast majority of screenshots you send. You need "a picture of a thing that looks the same."
The two conversions that fix 95% of screenshot bloat:
PNG → JPG (for photos, long scrolling screenshots, anything with images)
JPG is lossy, which is exactly what you want for content-heavy screenshots. A 30 MB PNG full-page screenshot becomes a 1–2 MB JPG with quality indistinguishable from the original. You can try it here: PNG to JPG.
The classic rule of thumb: if your screenshot is mostly content (photos, screenshots of websites, images in a document), JPG is dramatically smaller and nobody can see the difference.
PNG → WebP (for basically everything else, especially web upload)
WebP is Google's modern replacement for both PNG and JPG. It supports lossy *and* lossless compression, transparency, and animation — and it consistently produces files 25–50% smaller than JPG at equivalent quality. Run your file through PNG to WebP.
If you're uploading to a CMS, sending screenshots to a teammate, or attaching to a bug report, WebP is nearly always the right call. Every modern browser, Slack, Notion, and Linear supports it.
When to Keep PNG
For literally everything else — bug reports, Slack messages, screenshots-in-docs, emails, inspiration captures, notes — convert and move on.
The "Full Page" Screenshot Trap
The worst offender by a mile: browser extensions that take full-page scrolling screenshots.
A 12,000-pixel-tall PNG of a news article can be 80 MB. The file is useless — too big to email, too big to Slack, takes 20 seconds just to load in Preview. But you took the screenshot for a reason and now you're stuck with it.
Drop that PNG into PNG to JPG at 85% quality. It'll come out around 3–5 MB. Same content, same readability, 1/20th the size.
This is the single most useful conversion on the internet that nobody knows about.
Why Nobody Told You This
PNG became the default screenshot format on macOS around 2007, back when screens were 1024×768 and screenshots were small by default. Nobody bothered to change the default when retina displays arrived in 2012 and quadrupled the pixel count overnight, and nobody's bothered since.
You can actually change the default screenshot format on macOS:
```
defaults write com.apple.screencapture type jpg
killall SystemUIServer
```
Run that once and every future screenshot lands as JPG. Change `jpg` to `heic` if you want even smaller files (but lose some compatibility). For anything already on your disk, just run it through a converter.
Windows users: the Snipping Tool saves as PNG by default too. Use Paint.NET or any image app to re-save as JPG, or run through FluidConvert.
Bottom Line
PNG was designed when a "large" screenshot was 500 KB. We now take screenshots of 5,000-pixel-tall web pages on 6K monitors and wonder why our files won't send.
Lossless format. Lossy use case. That's the mismatch.
For 95% of screenshots — everything you're sending to a coworker, dropping in a bug ticket, embedding in a doc, or posting in Slack — JPG or WebP at decent quality is visually identical and a tenth of the size. The conversion takes 10 seconds. The file opens instantly on the other end.
Your video already figured this out. Your screenshots are waiting for you to catch up.