We wanted to design something that would work best with Casper mattresses but also work with other options!
Here are the respective dimensions for the Foundation by size:
Twin Casper: 37.5" x 74" x 7.75"
Twin XL Casper: 37.5" x 79" x 7.75"
Full Casper: 52.5" x 74" x 7.75"
Queen Casper: 59.5" x 79" x 7.75"
King Casper: 75" x 79" x 7.75"
California King Casper: 71" x 83" x 7.75"