Upload Full-Size Images to WordPress — Let It Handle the Rest

One of the most common mistakes I see with WordPress sites: people carefully resize their images to some arbitrary dimension before uploading them. 800 pixels wide, maybe, or whatever they think looks right on their screen. Don’t do this.

How WordPress handles images

When you upload an image, WordPress automatically generates multiple versions of it at different sizes. These sizes are defined by your theme and your settings. A typical setup might create a thumbnail (150 x 150), a medium version (300 wide), a large version (1024 wide), and the full original.

When a page loads, WordPress (or more precisely, your theme) serves the appropriate size for each context. A thumbnail in a grid, a larger version on a detail page, a full-width hero image. The system is designed to pick the right size automatically.

The problem with pre-resizing

If you resize an image to 800 pixels before uploading, that 800-pixel version becomes your original. WordPress can create smaller versions from it, but it can’t create larger ones. So if your theme needs a 1200-pixel hero image, it’s stuck stretching your 800-pixel upload — and the result looks soft and pixelated.

You’ve also locked yourself in. If you change themes or redesign your site, the new theme may need different sizes. WordPress can regenerate thumbnails from the original, but only if the original is large enough.

What to do instead

Upload the full-size image straight from your camera or editing software. If it’s 4000 pixels wide, upload all 4000. WordPress will generate every size it needs. On Katherine Marks’ architectural photography portfolio, for example, WordPress generates multiple sizes from each upload — thumbnails for the grid, large versions for the detail pages, and full-width images for the hero sections.

Do compress the file before uploading. A 4000-pixel JPEG doesn’t need to be 12 MB — compress it to a reasonable file weight (see my post on compressing images). That’s about file weight, not pixel dimensions.

Don’t resize the pixel dimensions. That’s WordPress’s job.

The short version

Compress: yes. Resize: no. Let WordPress do what it was designed to do.