Complete Guide to Mobile Banner Ad Sizes: Which Size Works Best?

Understanding Mobile Banner Ad Sizes

Choosing the right banner size can significantly impact your ad revenue. Let's dive into the most common mobile banner formats and their performance characteristics.

Standard Banner Sizes

320x50 (Mobile Banner)

The most common mobile banner size, appearing at the top or bottom of the screen.

Pros: Non-intrusive, high fill rate, works on all devices
Cons: Lower eCPM due to smaller size
Best for: Apps requiring constant ad visibility without disrupting UX

300x250 (Medium Rectangle)

A larger, more prominent banner that typically appears within content.

Pros: Higher eCPM, better engagement, more creative space
Cons: More intrusive, requires dedicated placement
Best for: Content feeds, between sections, natural breaks

320x100 (Large Mobile Banner)

Double the height of standard banners, offering more visibility.

Pros: Higher CTR than 320x50, still relatively non-intrusive
Cons: Takes more screen real estate
Best for: Premium placements, high-value screens

Adaptive Banners

Automatically adjusts to the device's screen width for optimal display.

Pros: Perfect fit on any device, higher fill rates
Cons: Less predictable layout
Best for: New apps, cross-device experiences

Performance Comparison

Size	Avg eCPM	CTR	Fill Rate
320x50	$0.50-1.00	0.3%	95%+
300x250	$2.00-4.00	0.8%	85%
320x100	$1.00-2.00	0.5%	90%
Adaptive	$1.50-3.00	0.6%	95%+

Best Practices

Test multiple sizes: A/B test different banner sizes in your app
Consider context: Use larger banners in content-rich areas
Monitor metrics: Track both revenue and user experience metrics
Refresh wisely: Implement smart refresh intervals (30-60 seconds)

Conclusion

The best banner size depends on your app's layout and user experience priorities. Start with adaptive banners for flexibility, then optimize based on your specific performance data.