Compress Images Online Free
Shrink the file size of JPG, PNG and WEBP images with a live quality slider. Perfect for email attachments, faster websites, and staying under upload limits. Your image never leaves your device — all compression runs in your browser.
Why compress images?
Modern phone cameras produce photos of 5–12 MB each. That is wasteful for email, slow to upload, and bad for website loading speed. Compressing an image re-encodes it at a smaller size while keeping it visually almost identical. A 6 MB photo often drops to 300–600 KB with no obvious quality loss.
JPG vs WEBP vs PNG
- JPG — best all-rounder for photographs. Smallest files at high quality.
- WEBP — Google's modern format, typically 25–35% smaller than JPG at the same quality. Great for websites.
- PNG — lossless, keeps transparency. Best for logos, screenshots and graphics, but larger files.
How to compress
- Drop your image into the box above.
- Pick an output format and, if you want, cap the width.
- Drag the quality slider and watch the file size update live.
- Click Download when you're happy with the size and look.
Everything runs locally — nothing is uploaded, and there are no watermarks or limits beyond your device's memory.
What the quality slider actually does
The quality number is not a percentage of anything you can see. In a JPG or WEBP encoder it scales the quantization tables — the size of the step the encoder rounds to when it stores the frequency coefficients for each block of pixels. Coarser rounding collapses more coefficients to zero. That is where the file savings come from, and it is also where the artifacts come from. At 90 you would have to zoom in to find the damage. At 40 the block grid starts showing through in smooth areas like sky or skin.
For photographs, 70–85 is where most people end up. Below 70 the losses get visible on gradients; above 85 the file grows quickly for a difference almost nobody notices.
The same number behaves very differently depending on the picture. Photos are mostly soft gradients and sensor noise, which quantization handles gracefully. A screenshot is the opposite: hard black-on-white text edges, big flat color regions, one-pixel UI lines. Sharp transitions need exactly the high-frequency coefficients the encoder discards first, so you get grey halos around letters and mottling across flat backgrounds at a setting that caused no trouble at all on a photograph. If there is text in the image, keep quality at 90 or above, or use PNG.
Resizing usually beats lowering quality
Dragging the quality slider down is the first thing most people try. Capping the width is usually the better move, because pixel count scales with the square of the dimension. A 4000px-wide photo holds around 16 megapixels; the same photo at 2000px holds 4. That is three quarters of the data gone before the encoder does anything — and if the image ends up in an 800px-wide column, every one of those pixels was being thrown away by the browser anyway.
Rough targets by use:
- Email or messaging — 1600–1920px wide is more than enough for anyone viewing on a phone or laptop.
- Website hero or full-width banner — 1920px, or 2560px if you care about high-DPI screens.
- Blog body image — 1200px covers most content columns at 2x.
- Thumbnail or avatar — 400px or less.
- Printing — the one case to leave the original alone. Figure roughly 300 pixels per inch of printed size, so an 8×10 print wants about 2400×3000.
Compressing something that is already compressed
Every JPG save runs a fresh round of quantization, and the artifacts left by the previous save are now part of the image the encoder is trying to reproduce faithfully. Re-encode the same file five times at 75 and the result looks worse than a single save at 60 would have. This is generation loss, and it is why you should always start from the best original you still have — the file straight off the camera, not the copy that came back from a chat app. Converting a battered JPG to PNG does not undo it either; PNG just stores the artifacts losslessly. If you are choosing an output format at the same time, WEBP gives the smallest result and JPG the widest compatibility.
Size targets people actually need to hit
Gmail and Outlook both cut off attachments around 25 MB, and that ceiling counts the encoded attachment, which is bigger than the raw file. Three or four modern phone photos will hit it. Dropping them to 1920px at quality 80 usually gets a dozen photos comfortably under the limit.
On the web, a single image past a few hundred kilobytes is worth a second look, and a page that ships several megabytes of images will feel slow on a phone connection no matter how fast the server is. Forums, job boards and marketplace listings tend to cap uploads somewhere between 2 and 8 MB per file, and many quietly cap pixel dimensions too — if an upload keeps failing without a clear error, try 1920px wide before assuming the site is broken.
Frequently asked questions
How do I compress an image for free?
Drop a JPG, PNG or WEBP into the box above, drag the quality slider until the size readout looks right, then download. Nothing is uploaded — the encoding happens in your browser.
Does compressing lose quality?
A little, by design. Lower settings mean smaller files and more visible artifacts. On a photo, 70–85 typically cuts the size by most of its original bulk with nothing obvious to the eye. The before and after previews update live, so you can find the point where it starts to show.
Is there a size limit?
No server limit, because there is no server involved. The practical ceiling is your device's memory, so large photos are fine on any recent phone or computer.