Last reviewed:
On this page
How it works without uploading anything
Most online resizers send your photo to a server, resize it there and send it back. This one doesn't. Your browser already knows how to open an image, draw it at another size and save it again; this page just asks it to do that with the measurements you choose. When it shrinks an image, it takes care to keep it sharp.
Because nothing is uploaded, nothing is stored with us, nothing can leak and there is nothing to delete afterwards. If you'd like to check, open your browser's Network tab (press F12), resize a photo and watch: nothing goes out.
A common problem elsewhere: a photo taken with the phone held upright that comes out lying on its side. Not here: the browser reads how the phone was held and straightens the image before resizing it.
Pixels or percentage: which one?
In pixels, you set the final size — 1,200 wide, say. That's what a website, a marketplace or a form with an exact requirement asks for. Fill in only the width and the height follows; fill in only the height and the width follows. With both filled in and “Keep proportions” ticked, the image fits inside that box without cropping or stretching.
In percentage, you say how much you want: 50 % leaves each side at half its length, and the image ends up with a quarter of the pixels. It's handy for a batch of photos in different sizes that you just want smaller by the same amount.
If you untick “Keep proportions” and fill in both width and height, both measurements come out exactly as you asked, and the image can end up stretched or squashed. Only do that on purpose.
Shrinking is safe; enlarging doesn't add detail
When you shrink, only the pixels the screen would have shown anyway are left. Enlarging works the other way round: the browser makes up new pixels from their neighbours, so the photo stays the same, just bigger and softer. This tool can't bring back detail the original never had, and enlarging a lot tends to leave it blurry.
For the browser's own safety, the result can be at most 8,000 pixels on a side and 36 million pixels in total. Above that, the file's row tells you so instead of handing you a blank file.
Resizing also makes the image lighter
A photo straight from a phone is often 4,000 pixels wide, and the place it ends up — a product card, a blog post, a listing — might show it at 800. Lighthouse, Google's speed audit, says a page should never serve images larger than the version shown on the visitor's screen: anything beyond that is wasted weight that slows the page down.
Going from 4,000 to 1,200 pixels wide removes more than 90 % of the pixels. That isn't the same as 90 % less file weight, because weight also depends on format and quality, but it's the biggest saving available. After resizing, you can shrink it further with the image compressor.
Same format or another?
By default the file comes out in the format it went in: JPG stays JPG, PNG stays PNG and WebP stays WebP. If the browser can't save the original format, as with a GIF, the file comes out as PNG. You can also pick WebP or JPEG.
The quality control works for JPEG and WebP (the page shows it from 40 to 100). PNG doesn't lose quality when it's saved, so it has no such control: to make a PNG lighter you have to reduce its dimensions or change format. When you save as JPEG, a transparent background turns white, because JPEG has no transparency.
Doing it once is easy. Doing it forever is the problem
Resizing a handful of files by hand works fine. It stops working when images arrive every week, when someone else uploads them, or when the same picture has to exist at four sizes for four screens.
That's the job NimboCDN does on your WordPress site: it prepares each image at the size the visitor's screen will really show and in the format their browser accepts, and serves it from our side, not yours — as WebP on the free plan and AVIF on the Pro plan, which is usually lighter still. You install the connector and the delivery changes; nothing in your library is rewritten.
To find out whether it's worth it for your site, the image size checker weighs what your pages deliver today and estimates what they would weigh afterwards.
Questions
Are my images uploaded anywhere?
No. Everything runs in your browser, on your device: there is no upload and no copy on our side. To check, open the Network tab of your browser's developer tools (press F12) and watch that nothing goes out.
Is there a limit?
Up to twenty files at a time, up to 25 MB each, and the result can be at most 8,000 pixels on a side and 36 million pixels. The limit is there because the work happens on your own device, and a phone with twenty large photos open at once runs out of memory.
How do I make a photo smaller without distorting it?
Leave “Keep proportions” ticked and fill in only the width or only the height. The other measurement is worked out from the photo's own proportions.
Does the image lose quality when it is resized?
When you shrink, some pixels go, and that's what brings the weight down. In JPEG and WebP the file is saved again already compressed, with a small loss of detail, which is why quality starts at 90. In PNG, only the dimensions change.
Does it keep my photo's data (date, location, camera)?
No. When the file is saved again, that hidden data (the EXIF), such as the GPS location and the camera model, doesn't come along. The photo's rotation is fixed first, so it comes out the right way up. Keep your originals if you need that information.
What about animated GIFs?
Only the first frame is kept, so this isn't the right tool for them. An animation almost always works better as a video.
Do I need an account?
No. No account, no email, no card. The page doesn't even know who you are.