Mulch Calculator
Mulch for a bed, in cubic yards for a bulk load or bags if you are buying by the bag. Depth is the decision that matters, and more is not better.
Mulch needed
1.56cubic yards
- Cubic yards
- 1.56
- Cubic feet
- 42.0
- Cubic metres
- 1.19
- Weight
- 0.59 short tons
- Tonnes
- 0.53
- 2 cu ft bags
- 21
- Includes a 5% waste allowance. The bare figure is 1.48 cubic yards.
- Bulk delivery is usually cheaper than bags past about three cubic yards.
- Densities are mid-range trade figures. Loose material settles and its weight changes with moisture, so treat the tonnage as an estimate.
About the mulch calculator
Mulch is sold by volume, so the calculation is bed area multiplied by depth. The only real trap is units: depth is in inches while the bed is measured in feet, and three inches is a quarter of a foot rather than three.
Two to three inches is enough to suppress weeds and hold moisture. Deeper than four starts working against you, keeping light rain off the soil and starving shallow roots of air. Topping up an existing layer to the target depth beats adding a full new layer every year.
There are 27 cubic feet in a cubic yard and mulch is bagged in two cubic foot bags, so a yard is thirteen and a half bags. Past about three cubic yards a bulk delivery is usually cheaper, though bags are far easier if you have nowhere to tip a load.
What it works out
- Cubic yards for ordering in bulk
- Bag counts, at whatever size your bags are
- Bark, wood chip, compost or topsoil
The formula
Cubic yards = (Length × Width × Depth) ÷ 27
Mulch is sold by volume, so the calculation is the bed's area multiplied by how deep you want it. The only real trap is mixing units: depth is in inches while the bed is measured in feet, and three inches is a quarter of a foot, not three.
There are 27 cubic feet in a cubic yard, which is where the division comes from. Bagged mulch is almost always two cubic feet a bag, so a cubic yard is thirteen and a half bags — a useful number to know when you are deciding between bags and a bulk load.
Depth matters more than people expect. Two to three inches is enough to suppress weeds and hold moisture. Deeper than four starts to work against you: it keeps water off the soil in light rain and can suffocate shallow roots.
- Length and Width
- The bed dimensions. For a curved border, pace out the average length and width — the result is close enough.
- Depth
- How thick you want the layer. Two to three inches for most beds.
- Material
- Changes the weight, not the volume. Bark is light, compost and topsoil far heavier.
A worked example
A twenty by eight foot border, mulched three inches deep in bark.
That works out to 1.56 cubic yards.
- Cubic yards
- 1.56
- Cubic feet
- 42.0
- Cubic metres
- 1.19
- Weight
- 0.59 short tons
- Tonnes
- 0.53
- 2 cu ft bags
- 21
Questions
How many bags of mulch are in a cubic yard?
Thirteen and a half, since mulch is bagged in two cubic foot bags and there are 27 cubic feet to the yard. In practice you would buy fourteen.
How deep should mulch be?
Two to three inches. That is enough to hold moisture and block light from weed seeds. Deeper than four inches can shed light rain before it reaches the soil and starve shallow roots of air.
How much does a yard of mulch cover?
About 160 square feet at two inches deep, or roughly 108 square feet at three inches. A cubic yard spread one inch thick covers 324 square feet.
Is it cheaper to buy mulch in bags or in bulk?
Bulk is usually cheaper past about three cubic yards, which is around forty bags. Below that the delivery charge tends to cancel out the saving, and bags are far easier to move and store.
How much does a yard of mulch weigh?
Bark mulch runs around 400 to 800 pounds a cubic yard dry, and considerably more after rain. Compost and topsoil are much heavier — a yard of topsoil is close to a ton, which matters if you are moving it by wheelbarrow.
Should I remove the old mulch first?
Not usually. Top up to your target depth rather than adding a full layer on top of what is there, or the total gets too deep after a couple of seasons. Break up any crust on the old layer before adding.