Mulch & Soil Calculator

Bags or cubic yards for mulch, topsoil, or a raised garden bed.

Length (ft)

Width (ft)

Depth (in)

2–3" for beds; 3" suppresses weeds best

Mulch and soil are sold in two completely different units — bags and cubic yards — and the crossover point matters. This tells you how much you need and which way is cheaper.

How it works

Volume is simply the area times the depth: length × width × (depth ÷ 12) gives cubic feet. Divide by 27 for cubic yards. Bag counts come from the volume printed on the bag (2 cubic feet is common). Raised beds get about 10 percent added, because soil settles noticeably after the first watering.

Example

A 20 × 10 foot bed at 3 inches deep is 50 cubic feet — about 1.9 cubic yards, or 25 two-cubic-foot bags.

Tips & common mistakes

Around 2 cubic yards, bulk delivery becomes dramatically cheaper than bags — often less than half the price — and you no longer have to open and haul 27 bags.
Two to three inches is the sweet spot for mulch. Less and weeds come through; more and you starve the soil of air and can start rotting the plants you are trying to protect.
Keep mulch away from tree trunks and stems. Piling it against the bark ('mulch volcanoes') traps moisture and kills the tree slowly.
For a raised bed, order more than the math says. Fresh soil settles by roughly 10 percent after the first few waterings, and topping up later means buying a second small quantity at a worse price.

Frequently asked questions

How many bags of mulch are in a cubic yard?

About 13 and a half, if the bags are 2 cubic feet each. There are 27 cubic feet in a cubic yard.

How deep should mulch be?

Two to three inches. That is enough to suppress weeds and hold moisture without suffocating the roots.

Is it cheaper to buy mulch in bags or bulk?

Bulk, once you need roughly 2 cubic yards or more — often by a wide margin. Below that, the delivery fee usually cancels out the savings.