Cost of Your Seaweed Mat Posted on March 10, 2017 by Jim Schillinger - Updated March 14, 2022 Size Small Large Dimensions 7' 6" x 20' 4" 12' 6" x 20' 4" Price $310.00 $410.00 Life expectancy of your mat is 7 - 10 years. This is based on proper usage, handling and storage. Both small and large mats are only available thru our distributors.