How to Compress Images Without Wrecking the Quality

A 6 MB photo straight off a phone camera is fine sitting in your gallery. Attach forty of them to an email, or drop one into a website hero slot, and suddenly the size matters a lot. Compression is how you get the same picture at a fraction of the bytes — and most of the time nobody can tell you did it.

Here’s what actually moves the needle, and where people usually get it wrong.

Lossy vs lossless, in one paragraph

JPEG and WebP throw away data you’re unlikely to notice — subtle colour steps, fine noise in a blue sky. That’s why they get small. PNG keeps every pixel exactly, which is great for a logo and terrible for a 12-megapixel photo. So the first question isn’t “what quality?” — it’s “am I even using a format that can compress this?” A PNG photo run through any compressor at any setting will barely budge, because there’s nothing safe to discard.

Pick a quality, then trust your eyes

For JPEG, the useful range is roughly 70–85%. I usually start at 75 and only go higher if the image has a lot of fine texture — hair, foliage, fabric weave — where artefacts show up first. Below 65% you start seeing blocky patches around sharp edges, and once you spot them you can’t unsee them.

A few rough numbers from real photos:

A 5 MB JPEG at 75% often lands around 1–1.5 MB — a 70%-ish drop with no visible loss.
The same photo saved as WebP at 75% frequently comes in another 25–30% smaller than the JPEG.
Screenshots and flat-colour graphics compress worse as JPEG and better as PNG or WebP, so don’t force JPEG on them.

The Image Compressor shows the before and after side by side with the exact percentage saved, so you’re never guessing whether you went too far.

When to reach for WebP

WebP is the quiet winner for most web use. It does lossy compression like JPEG, lossless like PNG, and keeps transparency — all in one file. If you’re putting images on a site you control, it’s usually the right default. Every current browser reads it.

The exception is anything leaving your control. Email attachments, files headed into an old version of Word, a design a client will open in who-knows-what — stick with JPEG or PNG there. A broken image in someone’s inbox is a worse outcome than a slightly bigger file.

Do it without uploading anything

Plenty of “free” compressors quietly ship your photo to a server, run it through the same canvas trick your browser already has, and send it back. That’s a privacy cost for zero benefit. Modern browsers can re-encode an image locally in a fraction of a second.

The Image Compressor runs entirely on your device:

Drop a JPEG, PNG, or WebP onto the tool.
Slide the quality down and watch the saved-size figure update.
Switch the output to WebP if you want the smallest possible file.
Download — your original on disk stays exactly as it was.

Nothing gets uploaded, which means it’s fine for passport scans, contracts, or photos you’d rather not hand to a random website.

Want to shrink a folder of photos before your next upload? Open the Image Compressor and see how many kilobytes you can drop before the picture stops looking right.