300×250 Ad Size: Medium Rectangle
The 300×250 medium rectangle is the most widely used display ad size on the web. It fits in a sidebar, between paragraphs and on almost every phone, so advertisers almost always have creatives ready for it. That high demand is why it is often one of the best earners.
Specs
| Spec | Value |
|---|---|
| Name | Medium Rectangle (also called MPU, inline rectangle) |
| Dimensions | 300 × 250 pixels |
| Aspect ratio | 6:5 |
| Devices | Desktop and mobile |
| High-resolution version | 600 × 500 pixels (2×), scaled down |
| Typical file size | Keep images under 150 KB. Google Ads limits uploaded image ads to 150 KB. |
| Formats | JPG, PNG, GIF or HTML5 |
Where to place a 300×250 ad
- Inside the article, after the first few paragraphs
- Sidebar, near the top
- Between items in a list or feed
- Below the article, before comments
Pros and cons
| Pros | Cons |
|---|---|
| ✓ Huge advertiser demand on desktop and mobile ✓ Fits phones without resizing ✓ Works well in the content where readers look | ✗ Very common, so readers can tune it out ✗ Several on one page can feel cluttered |
Tips for 300×250 ads
- Allow 300×600 in the same sidebar slot to raise competition.
- On mobile, centre it and reserve its height to avoid layout shift.
- Reserve the slot’s height in your layout so the page doesn’t jump when the ad loads. See Core Web Vitals and ads.
Make a 300×250 banner for free →
Related ad sizes
- 336×280 Large Rectangle
- 300×600 Half Page
- 320×100 Large Mobile Banner
- 250×250 Square
- All banner ad sizes with live previews
Frequently asked questions
Why is 300×250 called a medium rectangle?
It is the IAB name for this format. In the UK it is also called an MPU (mid-page unit).
Is 300×250 good for mobile?
Yes. It is narrower than almost every phone screen, so it is one of the best sizes for mobile in-content ads.
Want to know what this slot could earn? Try the ad revenue calculator, or look up terms in the ad tech glossary.