Soil & compost
How much soil do I need to fill a raised bed?
Length x width x depth in feet, converted to bags. A 4x8 bed 10 inches deep takes about 26.7 cubic feet, roughly 14 two-cubic-foot bags.
How this works
Length × width × depth, converted to bags and yards. The mix split is the classic square-foot recipe: equal thirds compost, coir or peat, and vermiculite.
Questions people ask
How many bags of soil for a 4x8 raised bed?
About 14 bags at 2 cubic feet each for a 10-inch depth, or 27 of the 1-cubic-foot bags. Bagged soil settles, so buy one extra rather than end up one short.
How deep does a raised bed need to be?
Six inches grows lettuce and herbs. Ten to twelve suits most vegetables and is what this calculator defaults to. Root crops and tomatoes are happier at 18.
Can I fill the bottom with logs or branches?
Yes, that is hugelkultur, and it saves real money on a deep bed. Fill the bottom third with wood, then use the calculator for the remaining depth only.