Enter your bed’s dimensions and desired mulch depth to find out how many cubic yards to order — or how many bags to grab at the store. Three inches is the sweet spot for weed suppression and moisture retention.
How to use this calculator
- Measure each bed’s length and width in feet (calculate beds separately and add them up).
- Enter depth in inches — 3 inches for new beds, 2 inches for annual top-ups.
- Optionally enter the price per bag to compare bagged vs bulk cost.
The math behind it
Cubic yards = length (ft) × width (ft) × depth (in) ÷ 12 ÷ 27. Bag counts divide total cubic feet by bag size (2 or 3 cu ft) and round up. One cubic yard covers about 108 square feet at 3 inches deep.
FAQs
How many bags of mulch do I need?
A 20×5 ft bed at 3 inches deep needs about 1 cubic yard — that’s 14 two-cubic-foot bags. For beds over ~100 square feet, bulk delivery by the yard is almost always cheaper than bags.
How deep should mulch be?
2–4 inches. Less than 2 won’t suppress weeds; more than 4 can suffocate roots and invite pests. Keep mulch a few inches away from tree trunks and plant stems.
Bagged or bulk mulch — which is cheaper?
Bulk mulch typically costs 30–50% less per cubic yard than bagged. Bags win for small touch-ups; bulk wins for whole-yard projects. Enter your local bag price above to see the comparison.
Related calculators
- Topsoil Calculator
- Sod Calculator
- Square Footage Calculator — for measuring beds