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Image compression: when lossy is good enough
Here's an unpopular opinion: most of the photos you upload are too big, and the quality slider is making you anxious for nothing.
A phone photo is 3 to 5 megabytes. A webpage with ten of those is 30–50 MB of weight your visitor downloads on mobile data, waiting, watching a spinner. Nobody does that. They leave. The fix isn't "a better photo" — it's making the photo smaller, and yes, throwing away some of it.
Lossy compression means data gets discarded. That sounds bad until you realize the data being discarded is the part your eye was never going to notice anyway. This isn't damage. It's editing out the inaudible.
The three formats, in plain words
JPG (JPEG). The old reliable. Brilliant with photos — skies, faces, gradients — because it throws away smooth, invisible detail. Terrible with text, sharp lines, or logos, where it smears. Pick a quality number; lower means smaller and softer.
PNG. Lossless. What goes in comes out pixel-identical. Great for screenshots, diagrams, anything with text or hard edges. The trade-off: PNG files of photos are huge, because photos have no repetition to exploit. Don't use PNG for a vacation shot.
WebP. The modern one. Does both lossy and lossless, and at the same quality usually beats JPG and PNG on size by 25–35%. Browser support is universal now (even Safari caught up in 2021). If you're publishing to the web and can use WebP, you probably should.
What "quality" actually controls
In a JPG or WebP tool, the quality slider isn't a measure of beauty — it's how much detail you're willing to drop. At 90%, almost nobody sees a difference from 100%. At 70–80%, photos still look fine on a normal screen and the file is a fraction of the size. Below 50%, edges go soft and flat areas get blocky; that's where it starts to show.
The practical rule I'd give a friend: for web photos, start at 75–80 and look. If it's still crisp on your screen, push to 70. You'll usually cut the file to a quarter of the original and never hear a complaint.
When lossy is absolutely good enough
- Blog and product photos. Shown at a few hundred pixels wide. The original was 4000px for no reason.
- Social posts. The platform re-compresses them on upload anyway. You're squabbling over bytes the network will delete for you.
- Email attachments and chat. Smaller means it sends, opens, and doesn't bounce.
- Site hero images. This is the heaviest thing on most pages. Shrink it and the whole site speeds up.
The one case where you must NOT compress
Screenshots, receipts, diagrams, scans of documents, anything with text or thin lines. Lossy formats smear those edges into mush a human can't read and a scanner definitely can't. Use PNG (or PDF, for documents) here. If you must shrink a screenshot, drop dimensions first, keep it lossless, and only then consider a light WebP lossless pass.
Also: don't re-compress a JPG you already compressed. Each pass throws away more, and the damage stacks — like photocopying a photocopy. Compress from the original, once.
Doing it without installing anything
Open the Image Compressor on tool80.com. Drop the photo in, pick WebP or JPG, drag quality to ~78, hit compress, download. That's the whole job. It runs in your browser — the image stays on your device and is never uploaded to a server, so a tax receipt or a private screenshot doesn't leave your hands. (The site runs basic anonymous analytics to check pages work; the details are in the privacy policy.)
For resizing a screenshot without quality loss, the Image Resizer is the better first step — shrink dimensions, then compress.
Quick answers
WebP or JPG for my site?
WebP, unless some ancient system can't read it. Same look, smaller file. JPG is the fallback, not the goal.
Why is my "compressed" PNG still 2 MB?
Because PNG keeps everything. It's the wrong tool for a photo. Switch to JPG/WebP and watch it drop.
Will compression hurt my print?
If you're printing, keep the original high-res file. Compression is for screens. A compressed web image printed at poster size will look soft — that's the only place it bites.
Smaller files really matter that much?
Yes. Image weight is the single biggest drag on page speed, and page speed is a ranking factor and a bounce factor. Shrinking photos is the cheapest performance win most sites have.
So stop treating the quality slider like a moral decision. For photos on a screen, 75 is fine, smaller is faster, and nobody's judging your pixels. Go shrink one.