Why an Image Looks Blurry or the Wrong Size

The original file was too small

If an image is stretched larger than its original dimensions to fill a space, it will look blurry or pixelated. Check the original file size in Media → Library (click on it to see its dimensions in pixels) – it needs to be at least as large as the space it’s being displayed in.

Heavy compression

Very aggressive compression (either from the original source, or an over-zealous optimisation plugin) can cause visible artefacts, especially on photos with fine detail. Try re-uploading a higher-quality original.

Wrong image size selected

WordPress automatically creates several sizes of each uploaded image. If a block is set to use a smaller generated size than the space available, it can look soft. Check the image block’s size setting in the block toolbar or settings panel.

Tip: As a rule of thumb, upload images at least twice as wide as their largest on-screen display size to allow for sharp display on high-resolution phone and laptop screens.