How to compress an image and reduce file size
Big image files slow down web pages, bounce off email limits, and eat storage. The good news: you can usually cut file size by more than half with almost no visible difference. Here's how.
Two things control an image's file size: its dimensions (how many pixels wide and tall) and, for JPG or WebP, its quality setting (how hard it's compressed). Adjust either — or both — and the file shrinks.
Why file size matters more than you'd think
A single photo straight off a phone is often 3–8 MB. That's fine on your camera roll, but it's a problem almost everywhere else: web pages load slowly (and Google notices), email providers commonly cap attachments around 20–25 MB, messengers and forums re-compress big uploads badly, and online forms frequently reject anything over a couple of megabytes. Compressing to a few hundred kilobytes solves all of this — usually with no visible difference at normal viewing sizes.
The fastest way: the PixPolish compressor
- Open the Compress Image tool and drop your photo in. Everything runs in your browser — the photo is never uploaded.
- Watch the before/after slider: drag the divider to compare the original and compressed version side by side.
- Adjust the quality slider. The new file size and the percentage saved update live as you drag.
- Pick JPG (works everywhere) or WebP (usually even smaller), then hit Download.
- Have a whole folder to shrink? Drop several photos at once — the same settings apply to all of them and they download together as a ZIP.
What quality setting should you pick?
| Use case | Quality | Why |
|---|---|---|
| Website / blog | 75–85% | Sweet spot: half the size, no visible loss |
| Email / messenger | 65–75% | Smaller is kinder; screens hide the difference |
| Print or keepsake | 90%+ or PNG | Keep maximum detail for later |
In plain words: JPG and WebP are lossy — they save space by discarding detail your eye is unlikely to miss, and the quality slider decides how aggressive that is. PNG is lossless — pixel-perfect but far larger for photos, which is why the compressor converts to JPG or WebP.
The other lever — resize the dimensions
If your image is far larger than it needs to be — say a 4000-pixel-wide photo used as a 600-pixel thumbnail — resizing is the biggest win of all. File size grows roughly with the number of pixels, so halving the width and height can cut the file to about a quarter before quality compression even starts. Use the resize tool first, then compress; our resize guide covers picking the right dimensions.
Common mistakes to avoid
- Compressing the same JPG again and again. Each re-save discards a bit more detail. Keep one original and compress copies from it.
- Saving screenshots or logos as low-quality JPG. Sharp text and flat colors show JPG artifacts quickly — keep those as PNG, or use WebP at high quality. See PNG vs JPG.
- Compressing before cropping or editing. Do your edits first, compress last, so you only lose detail once.
Troubleshooting
The result looks blurry or blocky? Raise the quality 10–15 points, or check whether the image was already tiny — enlarging a small image can't add detail back (though the AI upscaler can help). The file is still too big? Resize the dimensions down first, or switch from JPG to WebP.
Frequently asked questions
Does compressing reduce quality? Slightly, by design — but at 75–85% quality the difference is usually invisible at normal size. Compare with the slider before downloading.
Is my photo uploaded to a server? No. PixPolish compresses entirely in your browser; the image never leaves your device.
Can I compress many photos at once? Yes — drop multiple files into the compressor and download them all as one ZIP.
JPG or WebP? WebP is usually 20–30% smaller at the same quality and all modern browsers support it. Choose JPG only when an old system requires it.