Mulch Calculator

How much mulch you need: cubic yards or m³ for your beds at 2–4 inches (50–100 mm) deep, and how many 2 or 3 cu ft or 50–70 L bags.

Mulch is usually spread 2 to 3 inches (50 to 75 mm) deep on beds: enough to keep weeds down and hold moisture without smothering roots. It's sold in bags of 2 or 3 cubic feet in the US and 50 to 70 litres in the UK, or loose by the cubic yard or m³. A cubic yard covers about 162 square feet at 2 inches or 108 square feet at 3 inches. Enter each bed's size and depth and this calculator gives the cubic yards or m³, the bags of each size, and an optional cost. A 12 × 10 ft bed at 3 inches takes 1.11 cubic yards, which is 16 bags of 2 ft³ or 11 bags of 3 ft³, with 5% extra.

Units
Bag sizes
Area
ft
ft
in
Feet and inches work too: type 12'6 or 12.5.
t/yd³
%
Volume
1.17 yd³

31.5 ft³ · 0.892 m³

Weight
0.34 tons

677 lb · 0.31 tonnes

Bags
16

2 ft³ bag

Bags needed by size
2 ft³ bag16
3 ft³ bag11
1.5 ft³ bag21
50 L bag18
60 L bag15
70 L bag13
25 L bag36
1 m³ bulk bag1
How it was worked out
  1. Area: 12 ft × 10 ft = 120 ft²; × 3 in (0.25 ft) deep = 30 ft³
  2. 30 ft³ ÷ 27 = 1.11 yd³
  3. Plus 5% extra = 1.17 yd³
  4. 1.17 yd³ × 0.29 tons per yd³ = 0.34 tons (677 lb)
  5. 31.5 ft³ ÷ 2 ft³ per bag = 15.75, rounded up to 16 bags
Typical weights of common materials
Materialt/m³tons/yd³lb/ft³
Concrete2.402.02150
Gravel1.601.35100
Pea gravel1.601.35100
Crushed stone / crushed rock1.601.35100
River rock1.501.2694
Landscape rock / pebbles1.501.2694
Crushed limestone1.601.35100
Decomposed granite1.501.2694
Crusher run1.601.35100
Road base1.701.43106
Crusher dust1.501.2694
Aggregate (20 mm)1.601.35100
All-in ballast1.651.39103
MOT Type 1 sub-base1.801.52112
Sand1.601.35100
Topsoil1.301.1081
Garden soil1.301.1081
Fill dirt1.401.1887
Mulch0.350.2922
Bark chippings0.300.2519
Asphalt (compacted)2.321.96145

Loose, as-delivered figures; asphalt and concrete are as laid. Moisture, stone size and source change the real weight, so use your supplier's figure when you have it. Tons are US short tons (2,000 lb).

Common use cases

  • Mulch for flower beds and borders
  • Rings around trees and shrubs
  • Topping up last year's mulch
  • Comparing bagged mulch with a bulk delivery

How to use

  1. Choose feet and inches or metres and millimetres, and the country whose bag sizes you want.
  2. Enter the length and width of the area, or switch the shape to a circle, triangle or a known area. Use Add another area for L-shapes and separate beds.
  3. Enter the depth of mulch. 2 to 3 inches (50 to 75 mm) is typical for beds; a top-up of 1 inch is often enough each year.
  4. Check the density and the extra allowance. Change the density if your supplier quotes a different figure.
  5. Read the volume, weight and bag count, and add a price per ton, cubic yard, m³ or bag for a cost estimate.

FAQ

How much area does a cubic yard of mulch cover?

About 324 ft² at 1 inch deep, 162 ft² at 2 inches, 108 ft² at 3 inches and 81 ft² at 4 inches. A cubic metre covers 20 m² at 50 mm or 13.3 m² at 75 mm.

How many bags of mulch in a cubic yard?

27 cubic feet make a cubic yard, so 13.5 bags of 2 ft³ or 9 bags of 3 ft³. A cubic metre is 20 × 50 L or about 14.3 × 70 L bags.

How deep should mulch be?

Garden and extension services commonly recommend 2 to 4 inches (50 to 100 mm). Keep it a few inches away from stems and tree trunks rather than piling it up against them, which can cause rot.

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