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Image Compressor

Image Tools · Added

Reduce image file size locally with a quality slider and an immediate before-and-after comparison. Your files are read straight from the disk into the page — they are never uploaded, so a passport scan or an unreleased product shot is as safe here as a holiday photo.

Or drop files onto this box.

JPG, PNG, WebP, GIF, BMP or AVIF. Up to 20 files, 30.00 MB each. They are read from your device and never uploaded.

Output format

PNG is lossless, so quality does not apply to it. To make a PNG smaller, limit its longest side below or choose JPEG or WebP.

In pixels. Scaling a photo down is usually the single biggest saving. Images already smaller than this are left alone.

How to use the image compressor

  1. 1Choose one or more images, or drop them onto the box. JPG, PNG, WebP, GIF, BMP and AVIF are accepted.
  2. 2Pick an output format. "Keep original" re-encodes JPEG and WebP in place; GIF and BMP become PNG, because the canvas has no encoder for them.
  3. 3Drag the quality slider. Every change re-encodes automatically and the before-and-after sizes update with it.
  4. 4Optionally cap the longest side in pixels. On photos straight from a phone this usually saves more than the quality slider does.
  5. 5Check the preview, then download each image. The file is written straight to your downloads folder.

Examples

A phone photo for a web page

Input
4032×3024 JPEG, 4.1 MB · quality 75% · longest side capped at 1600 px
Result
1600×1200 JPEG, about 210 KB — roughly 95% smaller

Most of that saving is the resize, not the quality setting. A 4032 px wide photo is about six times wider than the space it will occupy on a page.

A PNG screenshot that will not shrink

Input
1920×1080 PNG screenshot, 480 KB · format "Keep original"
Result
1920×1080 PNG, about 470 KB — almost no change

PNG is lossless, so the quality slider does nothing to it. Switching the output to WebP at 80% typically brings the same screenshot under 90 KB with no visible difference.

A logo with a transparent background, saved as JPEG

Input
PNG with transparency · output JPEG · background #FFFFFF
Result
JPEG with the transparent area filled white

JPEG has no alpha channel. Without the fill those pixels would come out black, which is why the background colour appears as soon as you pick JPEG.

About the image compressor

What actually makes an image file large

Three things decide the size of an image file: how many pixels it contains, how much detail those pixels hold, and how aggressively the format is allowed to throw detail away. Most oversized images on the web are oversized because of the first, not the third. A modern phone photographs at around 4000 pixels wide; a full-width image on a typical page is displayed at roughly 1200. Everything beyond that is downloaded, decoded and then discarded by the browser at draw time.

That is why this tool offers a size limit alongside the quality slider, and why the limit usually wins. Halving both dimensions removes three quarters of the pixels before the encoder is even involved. Quality settings work on what is left. Reaching for quality alone, and dragging it low enough to hit a size target, produces a visibly degraded image at dimensions that were never needed.

Lossy and lossless, and when each is the right choice

JPEG and WebP are lossy: they discard information the eye is poor at noticing, mainly fine colour variation, and they can be tuned by how much they discard. PNG is lossless — it compresses by describing repetition rather than by removing anything, so it always reproduces the original exactly, and a quality control would be meaningless for it.

The practical rule follows from what is in the picture. Photographs, with continuous gradients and no hard edges, compress extremely well in a lossy format and poorly in a lossless one. Screenshots, diagrams, logos and anything with text or large flat areas are the reverse: PNG handles them efficiently, while JPEG smears artefacts around every sharp edge. WebP is the one format that is good at both, which is why it is often the right answer for a screenshot that has to be small.

One caveat about repeated compression. Each lossy re-encode discards detail from what the previous one already discarded, and the damage accumulates in a way that no later step can undo. Compressing a compressed file — the usual cause of a photo that has gone blotchy after passing through several apps — is best avoided by always working from the original.

Why this runs in your browser

Every step here happens inside the page: the file is read with the browser's own file API, drawn onto an off-screen canvas, and re-encoded by the same engine the browser uses to display images. Nothing is sent anywhere, which is a meaningful difference for the images people most often need to shrink — a scanned passport for a visa form, a photograph of a signed contract, a medical letter, a product shot before launch.

There is a practical trade-off in that choice, and it is worth stating rather than glossing over. A server-side tool can run specialised encoders such as MozJPEG or a full PNG optimiser, and squeeze out somewhat more at the same visual quality than a browser canvas will. What you get in exchange is that the file never leaves your machine, the tool works offline, and there is no queue, no upload wait and no copy of your image sitting in someone else's temporary directory.

Frequently asked questions

Are my images uploaded anywhere?
No, and this is the tool where the question matters most: compression is normally a server-side job, so most sites offering it genuinely do upload your file first. Here the encoder is the one already built into your browser. The image is decoded, re-encoded at the quality you picked and written back out without leaving the tab, because there is no upload endpoint in the code to send it to. That is what makes a passport scan or an unreleased product shot no more exposed here than a holiday snap.
Why did my PNG barely get smaller?
PNG compression is lossless, so the quality slider has nothing to act on — the encoder must reproduce every pixel exactly. To make a PNG meaningfully smaller you have to either reduce its dimensions, or move it to a lossy format. WebP is usually the best of those: it handles transparency, which JPEG cannot, and is typically well under half the size at a quality setting nobody notices.
Why is my compressed file bigger than the original?
Usually because the original was already compressed harder than the setting you chose, and re-encoding it at a higher quality adds data back without recovering any detail. It also happens when a flat-colour PNG such as a screenshot or a chart is pushed through a JPEG encoder, which is a poor fit for large areas of identical colour. The result panel reports this as a percentage larger rather than hiding it — when you see it, lower the quality, switch format, or keep the original.
Does compressing an image reduce its quality?
For JPEG and WebP, yes — both are lossy, and the loss is permanent in the saved file. Around 70–80% the difference is very hard to see on a photograph, while below about 50% you will start to notice blocking around edges and banding in skies. PNG output is lossless and loses nothing. Because the loss compounds each time, always compress from the original file rather than from an already-compressed copy.
Does this remove EXIF data such as GPS coordinates?
Yes, as a side effect. Re-encoding through a canvas produces a new file from the pixels alone, so the camera's metadata block — including location, device model and timestamp — is not carried across. That is useful before posting a photo publicly, but it also means the metadata is gone from the downloaded copy for good. Keep the original if you rely on it.
Is there a limit on file size or how many images at once?
Up to 20 images of 30 MB each. The limit is about memory rather than policy: decoding happens in the tab, and a very large image at full resolution can exhaust what the browser will give a single page. Very large dimensions can also exceed the maximum canvas size on mobile, which is reported as a decode error on that image while the rest of the batch continues.

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