Free Image Compressor Online

Last spring I had to upload twelve photos of a rental flat to a letting agent's portal. The form capped each file at 500KB. My phone shoots 4.2MB photos. So I went looking for a compressor, landed on TinyPNG, and hit the free limit after twenty images across two sessions — plus a 5MB per-file ceiling and ads down the side. Their Web Pro plan fixes all of it for $3.25/month, billed annually.

iLoveIMG wants $4/month for the same escape from ads and limits. Both also upload every photo to their servers to do the work. For a flat listing that is fine. For scans of a passport, a payslip, or a signed contract, it is a decision I would rather not make.

Browsers have been able to re-encode images since 2011. There is no technical reason any of this needs a server or a subscription. So this tool does it locally: drop files in, watch the sizes drop, download. Thirty at a time, no account, no cap on how often.

What People Actually Use This For

Almost nobody wakes up wanting to compress an image. They want to get past something that is blocking them. Four situations come up constantly.

Upload Forms With a Hard KB Limit

Visa applications, university portals, insurance claims, job boards. Someone picked 200KB as the limit in 2009 and nobody has revisited it since. Modern phone photos are twenty times that. Drag the quality slider to about 60% and set the maximum dimension to 1280px and a 4MB photo lands somewhere near 150KB, still perfectly readable on the other end.

Making a Website Load Faster

Images are usually the heaviest thing on a page, which makes them the usual reason Largest Contentful Paint blows past Google's 2.5 second threshold. Two changes do most of the work: stop serving images wider than they are ever displayed, and stop serving PNG screenshots. A 1.4MB PNG of a dashboard converted to WebP at 80% quality routinely comes out under 120KB. Same picture on screen.

Email and Chat Attachments

Gmail rejects anything over 25MB, and fifteen holiday photos clear that easily. Resize to 1920px, compress at 80%, and the whole set fits with room to spare. Nobody receiving photos in an email thread is pixel-peeping at full resolution.

Sensitive Documents

A photo of your driving licence for a car rental. A bank statement for a mortgage broker. These need to be small, and they also need to not sit in a stranger's temporary upload folder. Because this runs client-side, the file goes from your disk to your own RAM and back to your disk. Re-encoding also strips the EXIF block, which means the GPS coordinates of where the photo was taken come off with it.

How to Get Good Results

Resize Before You Reach for Quality

This is the single biggest lever and most people skip it. Halving the width of an image removes three quarters of its pixels. Going from 4000px to 1920px cuts the pixel count by roughly 77% before the encoder has done anything at all. Compare that to dropping quality from 80% to 60%, which saves maybe 35% and costs you visible detail. Resize first, then compress.

80% Is the Number

For photographs, quality 80 is where the trade-off sits best. Between 75 and 85 the difference is genuinely hard to see without flipping between the two at full zoom. Below 60 you start noticing it in the places JPEG struggles: smooth gradients like skies and skin turn blotchy, and sharp edges get a faint halo. Flat graphics and screenshots with text are less forgiving — keep those at 85 or higher, or use PNG.

Send PNGs to WebP, Not to PNG

A browser's PNG encoder is not clever. Re-encoding an already-compressed PNG often produces a larger file, which is why Smart mode routes PNGs to WebP instead. WebP supports transparency, so logos and cutouts survive intact, and it is typically 60-80% smaller than the PNG it came from. Every browser released since 2020 displays it. The only real holdout is old email clients — if the image is going into an HTML email, use JPEG.

Compress Once, From the Original

JPEG and WebP are lossy, and the damage stacks. Compressing an already-compressed file to 80% does not give you 80% quality, it gives you 80% of something that was already degraded, and the artefacts from the first pass get baked in and amplified. Always start from the original file. If a result looks wrong, throw it away and re-do it from the source rather than adjusting the output.

Where This Tool Loses

Prices checked September 2026. The comparison that matters is not marketing copy, it is what happens when you actually need the thing.

That last-but-one row is the honest one. This tool uses the encoder built into your browser. Squoosh, which is Google's and also free and also client-side, ships MozJPEG and AVIF compiled to WebAssembly, and at matched quality it will usually beat us by 10-20% on file size. TinyPNG's own encoder is excellent too. If you are squeezing the hero image of a site you will look at every day for two years, use Squoosh and enjoy the extra 15%.

What Squoosh will not do is take thirty files at once. That is the whole trade here: we are the batch tool that never uploads and never counts. For one precious image, go elsewhere. For the forty photos you need under 500KB by this afternoon, stay.

10 Compression Mistakes Worth Avoiding

1. Serving a 4000px image in a 400px slot. The browser downloads every byte, then throws 99% of the pixels away. Resize to what you display.
2. Using PNG for photographs. PNG is built for flat colour and sharp edges. On a photo it produces files five to ten times larger than JPEG for no visible gain.
3. Using JPEG for screenshots with text. The opposite mistake. JPEG puts fuzzy halos around letters. Use PNG or WebP.
4. Compressing the same file repeatedly. Each pass permanently degrades the one before it. Keep the original somewhere.
5. Converting a transparent PNG to JPEG. JPEG has no alpha channel, so transparency has to become a solid colour. This tool fills it white, which is wrong on a dark page. Use WebP instead.
6. Chasing quality 100. It is often bigger than the original and indistinguishable from 85. You are spending bytes on nothing.
7. Forgetting the metadata. A photo straight from a phone carries GPS coordinates. Compressing here removes them, but check before publishing anything you have not re-encoded.
8. Judging quality at the wrong zoom. Artefacts you can only see at 400% do not exist for your visitors. Judge at the size it will be displayed.
9. Ignoring dimensions on retina. A 400px-wide slot on a 2× display wants an 800px image. Compress harder rather than sending fewer pixels.
10. Uploading confidential scans to whichever tool ranks first. Check whether the processing happens on your machine or theirs. For a payslip, that matters more than 15% of file size.