About this tool
Compression reduces file size while keeping the picture looking as close to the original as possible. A page carrying 5 MB photos and one carrying 500 KB photos feel noticeably different to load, and page speed feeds into search ranking. It also solves the everyday annoyances: attachments rejected for being too large, upload forms with a size cap, galleries that refuse the file.
The real work is finding the balance point, and seeing it rather than guessing. JPEG and WebP are lossy: lower the quality value and the file shrinks, but past a certain point you start seeing blotches in smooth gradients — skies, skin, plain backgrounds. Where that point sits differs from photo to photo, so there is no single correct number. This tool shows the estimated file size live as you move the quality slider, so you can watch both at once and stop where it still looks right. Your image is never uploaded. Editing and saving both happen inside your browser, so you can open files you would not want to hand to a server — photos with faces in them, internal documents, anything sensitive.
How to use
- Click "Pick an image & start" to open a file.
- In Export, choose JPEG or WebP. Quality can only be adjusted for these two formats.
- Move the quality slider and watch the estimated size. Starting around 80 and working down is a practical approach.
- Check the preview where colours change smoothly — sky, skin, flat backgrounds. If blotches appear, nudge the quality back up.
- Save. If it is still too large, resize the pixel dimensions first and then compress again.
Frequently asked questions
- What quality value should I use?
- For the web, 75-85 is a safe range: hard to tell apart from the original side by side, but substantially smaller. Below about 60, blotching in smooth gradients becomes visible. For anything going to print, stay at 90 or above.
- Why is there no quality slider for PNG?
- PNG is lossless, so there is no quality value to set — the option of trading a little fidelity for a smaller file simply does not exist in that format. To shrink a PNG, reduce its dimensions, or convert it to JPEG or WebP if you do not need transparency.
- Does compressing twice make it smaller?
- Marginally, and it costs quality every time. Lossy compression cannot be undone, so re-saving an already-compressed JPEG at lower quality stacks new artefacts on top of old ones. If you expect several rounds of editing, work in PNG and compress once at the end.
- Is WebP smaller than JPEG?
- At equivalent quality, usually by 20-30%. Every current browser supports WebP, so it is the better choice for anything you publish on the web. Some older applications and image viewers still cannot open it, so JPEG remains safer for files you send to other people.
- The file is not getting much smaller.
- Usually the pixel count is the culprit. There is a limit to what lowering quality can do for a 4000x3000 image. Resize it to around 1600 pixels wide first, then compress — that typically lands in the few-hundred-kilobyte range. Dimensions first, quality second.
- Is the quality loss permanent?
- In the saved file, yes — which is why keeping the original matters. While you are working, Ctrl+Z is available, and moving the slider does not alter the original, so you can try as many values as you like before saving.
- Should I use JPEG for screenshots and diagrams?
- Better not to. JPEG is designed for photographic images where colour varies smoothly, and it produces messy fringing around hard edges like text strokes and chart lines. Screenshots, diagrams, and text-heavy images do better as PNG, or WebP if size matters.
- Can I compress a whole folder at once?
- Automate > Batch lets you select multiple files and export them all with the same format and quality. Handy when the conditions are identical across many images.
- Is a compressed photo good enough to print?
- At high quality settings, yes. Bear in mind that print resolves far more finely than a screen, so artefacts invisible on a monitor can show up on paper. Use quality 90 or above for print, do not shrink the dimensions, and keep separate files for web and print.