Compress & Optimize Images

How to compress an image — 3 steps

1. 1

   Add your images

   Drop in JPG, PNG, or WebP files, one or many. Because compression runs locally there is no per-file upload cap to work around, so batches of camera-resolution photos are fine.

2. 2

   Choose how hard to compress

   Lower quality means a smaller file and more visible artefacts. Start around 80 and only go lower if you still need to hit a size limit.

3. 3

   Check the result, then download

   Compare the compressed version against the original before saving. If the saving is disappointing, the image is probably too large in pixel dimensions rather than too lightly compressed.

Dimensions usually matter more than quality settings

The most common reason an image is enormous is not weak compression — it is that the picture is far bigger than it will ever be displayed. A modern phone photo is often 4000 pixels wide. Used as a blog header shown at 1200 pixels, more than 90% of those pixels are thrown away by the browser at display time, after the visitor has already downloaded every one of them.

That is why resizing usually beats compressing. Halving an image's width and height quarters its pixel count, and the file shrinks roughly in proportion — a far larger saving than pushing JPG quality from 85 down to 60, and with no visible artefacts at all. A good order of operations is: resize to the largest size the image will actually be shown at, then compress, then check whether you still need to go further.

If you are hitting a hard limit — an upload form that rejects anything over 2MB, an email attachment cap, a job portal that wants a photo under 500KB — do both. Resize first to get most of the way there, then use compression to fine-tune under the threshold.

What compression actually removes, and where it shows

Lossy compression works by discarding information the human eye is poor at noticing: fine variations in colour, and detail inside busy areas. This is why the same quality setting can look flawless on one image and obviously degraded on another. Photographs of foliage, crowds, or textured fabric hide artefacts well. Smooth gradients — a clear sky, a studio backdrop, a soft shadow — show them as visible banding or blotches, because there is no detail to hide behind.

The other place artefacts appear is around hard edges, especially text. If your image contains lettering, a screenshot, or a logo, compress it gently or not at all; JPG compression is at its worst exactly where black meets white.

Compression is also cumulative. Every time a JPG is opened, edited, and re-saved it is re-compressed, and the losses stack up — an effect known as generation loss. Work from the original file rather than from an already-compressed copy, and compress once at the end rather than at each step.

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