Mulch Calculator
Mulch is sold by the bag or by the cubic yard, but beds are measured in feet. This calculator converts your bed size and desired depth into the volume you need, so you neither run short halfway through nor pay for a pile that sits in the driveway.
How to use this calculator
- Pick your units and the shape of the area – rectangle, circle, or a known total area.
- Enter the measurements. For irregular beds, break them into rectangles and add the areas.
- Enter the mulch depth. 2–3 inches (5–8 cm) suits most beds; 3–4 inches for weed-prone paths.
- Read the volume in cubic yards for bulk orders, or the bag count for bagged mulch (commonly 2 or 3 cu ft in the US).
How much mulch is right?
For most shrub and perennial beds, a layer of 2 to 3 inches of organic mulch such as shredded bark or wood chips suppresses weeds and holds moisture without smothering roots. Fine materials like compost-based mulch can go thinner; coarse wood chips on paths can go thicker. Keep mulch a few inches away from tree trunks and plant stems – piling it against bark (“volcano mulching”) invites rot and pests.
The math
Area (sq ft) × depth (in) ÷ 12 = cubic feet. Divide by 27 for cubic yards. A handy rule: one cubic yard covers about 324 sq ft at 1 inch, 162 sq ft at 2 inches or 108 sq ft at 3 inches. In metric, area (m²) × depth (cm) × 10 gives liters.
Topping up existing mulch
Organic mulch breaks down over time. If there is already an inch left, you only need to add the difference to reach your target depth – enter just the extra depth in the calculator.
Frequently asked questions
How much area does a cubic yard of mulch cover?
One cubic yard covers about 108 sq ft at 3 inches deep, 162 sq ft at 2 inches, or 324 sq ft at 1 inch.
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
How deep should mulch be?
Around 2–3 inches (5–8 cm) for most garden beds. Deeper than about 4 inches can limit air and water reaching the soil.
Can I use this for gravel or stone?
Yes, the volume math is the same. Stone is sold by weight as well as volume, so ask your supplier how many tons equal a cubic yard of that product.