Mulch Calculator
Work out how much mulch, compost or topsoil a project needs: enter each bed as a length by width, set the depth, and get the volume in cubic yards and cubic feet, the number of bags to buy, how much it weighs and how far one bag goes.
Counts round up to whole bags. Bulk delivery by the cubic yard works out cheaper than bags once a bed is more than a few square feet, and it saves carrying 40 lb sacks.
Formula and calculation
Worked example
Three beds of 12 × 4, 20 × 3 and 8 × 8 ft come to 172 sq ft. At 3 in deep that is 43 cu ft of bark mulch, or 1.5926 cu yd — 22 bags of 2 cu ft, since one bag covers 8 sq ft at this depth. It weighs about 0.48 tons (956 lb) and costs $88 at $4 a bag.
Bags or a bulk delivery?
Bagged mulch is convenient and easy to spread, but you pay for the bag, the printing and the pallet. A landscape yard sells by the cubic yard, typically tipping a scoop straight into a pickup or delivering a few yards at once, and the price per square foot of coverage is much lower. The break-even is around the point where you need more than a few dozen bags — on the numbers above, 6 cu yd of bagged mulch is roughly 80 bags to lift twice, once into the car and once into the bed.
How deep should mulch be?
Two to three inches is the working depth on an established bed: enough to suppress weeds and hold moisture, thin enough for rain to reach the soil. Four to six inches suits bare ground you are about to plant, and it settles to three within a season. More is not better. Piling mulch against a trunk keeps the bark wet and invites rot, and a deep layer over shallow roots can starve them of oxygen. Keep it a few inches clear of stems, walls and siding.
What the results mean
- Mulch needed
- The volume of mulch in cubic yards, the unit landscape yards sell and deliver in. One cubic yard is 27 cubic feet and covers about 108 sq ft at 3 in deep.
- Bags to buy
- How many bags to buy at the bag size you picked, rounded up to whole bags. A standard 2 cu ft bag is the common retail size.
- Total area
- The combined area of every bed you entered, in square feet.
- Volume
- The same volume in cubic feet, which is how bag yields are measured — useful for checking the bag count.
- One bag covers
- How many square feet one bag covers at the depth you set. At 3 in deep a 2 cu ft bag covers 8 sq ft.
- Weight
- What the mulch weighs in short tons (2,000 lb), using the density of the material you picked. This decides whether a pickup or a delivery truck is needed.
- Also
- The same weight in pounds. A cubic yard of wet mulch can weigh half a ton, so check your trailer rating before you load.
- Cost of the bags
- What the bags cost at the price you entered — the number of bags times the price per bag.
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cu ft, so it is 13.5 bags of 2 cu ft, 18 bags of 1.5 cu ft or 9 bags of 3 cu ft. Bags sold as 2 cu ft hold closer to 1.9 cu ft of settled material, so buy one extra bag per yard if the depth matters.
How much area does a bag of mulch cover?
A 2 cu ft bag covers 8 sq ft at 3 in deep, 12 sq ft at 2 in and 4 sq ft at 6 in. The coverage row above is worked out for your depth and bag size, and the coverage drops as the layer gets thicker.
How many square feet does a cubic yard of mulch cover?
One cubic yard covers about 108 sq ft at 3 in deep, 162 sq ft at 2 in and 324 sq ft at 1 in. Multiply your bed area by the depth in inches, then divide by 324 to get cubic yards: 400 sq ft at 3 in is 3.7 cu yd.
How much does a yard of mulch weigh?
Bark mulch runs about 600 lb per cubic yard dry, compost about 1,200 and topsoil about 2,100, and wet material is 20–40% heavier. That is the difference between a half-ton pickup carrying two yards of bark mulch easily and not moving at all with two yards of wet topsoil.
Should I put mulch over landscape fabric?
Fabric helps under gravel and stone paths, but under organic mulch it traps the fine material that breaks down and can leave a matted layer that sheds water. A 2–3 in layer on bare soil suppresses most weeds on its own, and what comes through pulls out easily. Keep fabric away from perennials that spread by root.