Bulk Image Compressor

How to compress images in bulk

1. Add your images. Drop up to 200 JPG, PNG, WebP, BMP, GIF or AVIF files onto the box above, or choose them from your computer. They stay on your machine.
2. Pick a quality. 75% is a good default for photographs on the web. Lower it if file size matters more than fine detail.
3. Compress and download. Every image is listed with its before and after size. Take them one at a time, or download the whole batch as a ZIP.

How much smaller will my images get?

It depends almost entirely on what the file already is. A photograph straight off a phone or a camera is usually saved at close to maximum quality and will typically lose 60–80% of its size at 75% quality with no visible difference on a screen. A JPG that has already been through a compressor may barely move — and if re-encoding it would make it larger, this tool keeps the original file instead of handing you a bigger one.

PNG is a lossless format, so the quality slider does not apply to it. If your PNGs are photographs rather than logos or screenshots, converting them to JPG or WebP with the format control is usually a far bigger saving than anything a PNG re-encode can offer.

Why compress in the browser?

Compression is arithmetic on pixels your computer already has. Sending an image to a server to have that done, then sending it back, is slower, costs someone money, and means your files sit on a machine you do not control. Doing it locally is faster for a large batch, works offline once the page has loaded, and is the reason this tool has no sign-up and no usage limit.

Choosing between JPG, WebP and PNG

• JPG — photographs. Universally supported, no transparency. The safe choice when the image is going somewhere you do not control.
• WebP — photographs and graphics. Typically 25–35% smaller than a JPG at the same visual quality, supports transparency, and is supported by every current browser.
• PNG — logos, screenshots, anything with sharp edges or transparency that has to stay pixel-exact.

Frequently asked questions

Are my images uploaded to a server?

No. Compression happens in your browser using the canvas API. Your images never leave your computer, which is also why the tool works with no account and no limit on how many times you use it.

How many images can I compress at once?

Up to 200 images per batch. They are processed a few at a time rather than all at once, so a large batch will not exhaust your browser memory.

Which formats are supported?

JPG, PNG, WebP, BMP, GIF and AVIF. The first three are written back as themselves; BMP, GIF and AVIF are read and returned as JPG, PNG or WebP, because a browser canvas can only write those three. You can also convert everything to JPG or WebP as you compress. Animated GIFs, animated WebPs and APNGs are refused rather than accepted, because a canvas only ever sees the first frame and the animation would be silently lost.

What quality setting should I use?

For photographs on the web, 70–80% is usually indistinguishable from the original at a fraction of the size. Below 50% compression artefacts become visible in flat areas such as skies.

Why did one of my images not get smaller?

Some images are already compressed as far as they usefully go, and re-encoding them would make them larger. When that happens the original file is kept and returned unchanged rather than handing you a bigger file. The exception is BMP, GIF and AVIF: a browser canvas cannot write those three, so they are always re-encoded to JPG, PNG or WebP and the row shows the real change in size — which for an already-small GIF or AVIF can be an increase.