Share the following list with your designers when you ask them to create your ads for Google or Facebook.
Rules for Creating Google Image Ads
Google Adwords Tips
1. Create ads in as many of the different sizes you can – not all sites offer all sizes, so use all the ad sizes to get as many impressions as possible.
2. If you can’t afford to create ads in all those sizes, some of the most popular sizes are:
250×250, 200×200, 468×60, 728×90, 300×250