The best size for your profile picture is 200px*200px. For other sizes see here:

These sizes are a guide and will be updated if needed. For users who cannot see the image above: 

Cover image: 800*600

Background image: 1920*1080

Profile header: 1920*300

Profile Avatar: 200*200

If you need any help getting your images to fit then email support@wakelet.com - we want to help you look your best!