Resize an image to 300x250 for a medium rectangle ad

Why 300x250 is the workhorse ad size

The medium rectangle is part of the IAB standard ad set, and almost every ad network and placement accepts it. It sits well inside articles and sidebars, which is why advertisers reach for it first.

The ratio is 6:5, slightly wider than tall. Design with that shape in mind so your headline and product do not get cropped when you fit a photo into the frame. The resize tool is preset to 300 by 250.

Keep the creative readable at small size

300x250 is not large, so a busy photo with small text turns to mush. Lead with one clear image and a short, high-contrast headline that survives at this size.

If your source is a different shape, crop to 6:5 first and keep the focal point away from the edges, since ad containers sometimes add a thin border.

Mind the file weight limit

Ad networks cap creative file size, often around 150 KB. After resizing, compress to a KB target to land under the network's limit, or convert to WebP where the platform allows it.

Everything runs in your browser. The creative is processed locally and never uploaded, so unreleased campaign art stays private.