Image Sizes Recommendations for Freyja

Minimum recommended sizes
Featured Images
1 Post Slide1800px X 525px

3 Post-Slide Center750px X 530px
4 Post Slide660px X 800px
Promo Box Images600px X 800
Gallery Images1400px X 530
Sidebar Widgets Images600px X indifferent

Size recommendations! The featured images should not be wider than 1600-1800px, and it’s important to save them for web at 72 dpi, to reduce the loading time of your website. When you see different image sizes in the demos of our theme you don’t worry: WordPress will resize your images automatically.
At this link, you can find how to save your images for web with an efficient online tool (compressor.io)