What size does a background photo for a NationBuilder website need to be?

When I’m adding a background image to my NationBuilder website page, what is the correct file size and aspect ratio?

Official Answer

The ideal background photo size for a NationBuilder website is 1600 x 900 pixels (16:9 aspect ratio) and a file size of not larger than 500kb. Smaller file sizes will improve page load times, conversion rates, and search engine ranking.