General photography guidelines
Key points to format your images before upload:
Only .jpg, .gif, or .png
2500 pixels width is ideal in most cases.
You don't need to resize your images if they're wider than 2500px and meet our other specifications. Images less than 1500px wide may appear blurry.
Use images 500 KB or less to help your site load quickly.
RGB
Name with key words
Squarespace Help Center “Editing and formatting images”.