320×480 Ad Size: Mobile Interstitial (portrait)
The 320×480 interstitial is a full-screen ad shown on phones in portrait mode, usually between pages or in apps. It is highly visible and earns high CPMs, but it must follow strict rules.
Specs
| Spec | Value |
|---|---|
| Name | Mobile Interstitial (portrait) (also called full-screen mobile ad) |
| Dimensions | 320 × 480 pixels |
| Aspect ratio | 2:3 |
| Devices | Mobile |
| High-resolution version | 640 × 960 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 320×480 ad
- Between page views on mobile web
- Between levels or screens in apps
Pros and cons
| Pros | Cons |
|---|---|
| ✓ Very high visibility and CPMs | ✗ Google penalizes intrusive interstitials that block content on mobile pages ✗ Can annoy readers if shown too often |
Tips for 320×480 ads
- Show it only between pages, never as the page loads, and cap the frequency.
- Use Google Ad Manager’s web interstitial format to stay within the rules.
- Reserve the slot’s height in your layout so the page doesn’t jump when the ad loads. See Core Web Vitals and ads.
Related ad sizes
- 480×320 Mobile Interstitial (landscape)
- 300×250 Medium Rectangle
- 320×100 Large Mobile Banner
- All banner ad sizes with live previews
Frequently asked questions
Are interstitial ads allowed on mobile websites?
Yes, between pages. Pop-ups that cover the main content right after a visitor arrives from search can hurt rankings.
What size is a mobile interstitial ad?
320×480 in portrait and 480×320 in landscape are the classic sizes. Modern formats also scale to the full screen.
Want to know what this slot could earn? Try the ad revenue calculator, or look up terms in the ad tech glossary.