Compare Two Images

Difference compares each pixel of A with the pixel in the same place in B. When their colours differ by more than about 4% (10 steps out of 255, averaged over red, green and blue), the pixel is marked red; smaller changes are ignored. Transparency isn’t compared, only colour. So:

• Identical images show no red at all, a quick way to confirm two files hold the same picture.
• Edits such as a removed object, changed text or a moved logo stand out clearly.
• Compression mostly changes pixels by less than the threshold, so even a low-quality JPEG copy shows only scattered red specks. Judge compression with the slider instead.

It compares from the top-left corner without scaling, so both images need the same width and height in pixels. If the sizes differ, most of the picture turns red. If one image has moved by a pixel or two, outlines and fine detail light up instead.

• Slider: both images are shown at the same width. If they’re the same shape they line up, even when one has fewer pixels: a half-size copy sits exactly over its original, enlarged to match, so it looks softer. If the shapes differ, the frame takes B’s shape and A is scaled to fill it, cutting off A’s edges.
• Overlay: the frame takes A’s shape and the whole of B is fitted inside it.
• Side by Side: each image keeps its own shape.
• Difference: needs matching sizes, so resize or crop one image to match the other first.

Phone photos stored sideways with a rotation tag are shown upright, and iPhone HEIC photos are converted on your device before they’re shown.

• Checking compression. Compress a photo with the Image Compressor, then put the original in A and the smaller copy in B. Drag the slider across fine detail, smooth skies and text, where compression shows first. If you can’t see a difference, the smaller file is fine to use.
• Before and after edits. Check that colour adjustments or retouching improved a photo and weren’t overdone.
• Spotting differences. Use Difference on two exports of a design, or two versions of a screenshot, to find what changed.

On a phone or tablet, drag sideways across the picture to move the divider, or tap where you want it. Swiping up or down still scrolls the page.

With a keyboard, press Tab to reach the picture, then use the arrow keys to move the divider 1% at a time, or 10% with Shift held down. Home and End move it to the edges.

There’s nothing to download, so take a screenshot to keep a comparison. There’s no zoom either, as each view fits the width of the page; to inspect a small area, crop the same part from both images and compare those. To change one image, press Clear and add both again.

Both images are opened and compared by your browser, on your own device. Nothing is uploaded, so it’s safe for unreleased designs and private photos.

To check, open your browser’s developer tools, watch the Network tab and compare two images: no request carries them. Apart from the page’s own code (such as the HEIC decoder, if you add an iPhone photo), the only requests are anonymous usage counts, described in our privacy policy. After your first visit, the tool works offline too.