Ok, I'm really confused lol. I'm putting mulch down in a garden bed that is 21ft long by 8 feet deep. That's 168 sq ft. So I did the math earlier without the site and I came up with 28 3 cubic ft bags. However, I used this site http://www.gardenplace.com/content/calculator/mulch_calc.html# and they are telling me I only need 3 bags. That's just does not seem right. What do you guys think. I figured doing the mulch 6 in thick just so I don't under estimate.