Google der ki:
“If positioned well, wide ad sizes can increase your earnings significantly. The sizes we’ve found to be the most effective are the 336×280 large rectangle, the 300×250 medium rectangle, the 728×90 leaderboard, the 300×600 half page, and on mobile the 320×100 large mobile banner.”
Most Successful Ad Sizes

Stefan der ki:
The top 3 banner sizes comprise 78% of all served ad impressions:
1. Medium Rectangle: 300×250
2. Leaderboard: 728×90
3. Wide Skyscraper: 160×600
10 Most Effective Banner Sizes

I’m founder and director of The Digital Agency; a certified Google Partner and Shopify Partner digital marketing agency operating in London and Istanbul. The Digital Agency has a solid track record of delivering high growth in eCommerce, Facebook & Google advertising, social media communication, search engine optimization, eCommerce and website production through 16 years of experience with 140 brands in 500 projects. Visit The Digital Agency here