acalculator

How much compost do I need to buy?

Type the area and how deep a layer of compost to spread. The compost calculator gives the volume in cubic yards, cubic feet and cubic metres, the rate per 1,000 sq ft, the bags to buy, and the cost of bulk compost.

Your numbers

Units
Compost to order
3.09 yd³

1,000 ft² at 1 in deep needs 3.09 yd³ of compost.

Cubic feet
83.33 ft³
Cubic metres
2.36 m³
Cubic yards per 1,000 sq ft
3.09
Bags
84

Compost to order: 3.09 yd³. 1,000 ft² at 1 in deep needs 3.09 yd³ of compost.

How to calculate

Computes the compost to spread over a lawn or garden bed from the area and depth, in cubic yards, cubic feet and cubic metres, with the rate per 1,000 sq ft, the bags and the cost.

Example with the default inputs (Area 1,000 ft², Depth of compost 1 in, Bag size 1 ft³): 1,000 ft² at 1 in deep needs 3.09 yd³ of compost.

Method: Compost = area × depth; cubic yards per 1,000 sq ft = depth in feet × 1,000 ÷ 27; bags = compost ÷ bag size, rounded up.

  • NC State Extension suggests 1 to 2 cubic yards per 1,000 sq ft (about 0.3 to 0.65 in) worked into the top 6 to 8 inches of heavy clay or sandy soil.
  • The volume is of compost as delivered, with nothing added for waste or settling.
  • The cost is the bulk price per cubic yard × the cubic yards; delivery is not counted.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Area 1,000 ft², Depth of compost 1 in, Bag size 1 ft³ gives Cubic feet 83.33 ft³, Compost to order 3.09 yd³, Cubic yards per 1,000 sq ft 3.08642, Bags 84.Source: NIST Handbook 44, Appendix C, General Tables of Units of Measurement (1 yd³ = 27 ft³; 1 ft = 12 in = 0.3048 m), https://www.nist.gov/pml/owm/nist-handbook-44-current-edition (retrieved 2026-10-03); NC State Extension, Extension Gardener Handbook, chapter 9 Lawns (for heavy clay or sandy soils, mix 1 to 2 cubic yards of compost per 1,000 square feet into the top 6 to 8 inches), https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns (retrieved 2026-10-03)
  2. Area 200 ft², Depth of compost 2 in, Bag size 1.5 ft³, Price per cubic yard $40.00 gives Compost to order 1.23 yd³, Bags 23, Estimated cost $49.38.Source: NIST Handbook 44, Appendix C, General Tables of Units of Measurement (1 yd³ = 27 ft³; 1 ft = 12 in = 0.3048 m), https://www.nist.gov/pml/owm/nist-handbook-44-current-edition (retrieved 2026-10-03)
  3. Area 107.6 ft², Depth of compost 1.969 in, Bag size 1.413 ft³ gives Cubic metres 0.5 m³, Bags 13.Source: NIST Handbook 44, Appendix C, General Tables of Units of Measurement (1 yd³ = 27 ft³; 1 ft = 12 in = 0.3048 m), https://www.nist.gov/pml/owm/nist-handbook-44-current-edition (retrieved 2026-10-03)

How it works

With the area A, the depth d, the bag size b and the price per cubic yard c:

  • Compost to order V = A × d, shown in cubic yards (27 ft³), cubic feet and cubic metres.
  • Cubic yards per 1,000 sq ft = d in feet × 1,000 ÷ 27.
  • Bags = V ÷ b, rounded up to a whole bag; shown only when a bag size is typed.
  • Estimated cost = V in cubic yards × c; shown only when a price is typed.

Rules. The area is above 0 and at most 10,000,000 m². The depth is above 0 and at most 2 m. A bag holds from 0.1 L to 100 m³. The price is from $0 to $100,000 per cubic yard. Nothing is added for waste or settling.

Exact arithmetic. Typed values are exact decimals (1 ft = 0.3048 m, 1 in = 0.0254 m), so an exact fit gives a whole number of bags without rounding up past it. Results round once, for display.

Output format. Volumes show 2 decimals; the rate shows 2 decimals; bags are whole numbers; cost shows dollars and cents. The raw volumes are in cubic metres.

Worked examples by hand

1,000 sq ft at 1 inch, 1 cu ft bags. V = 1,000 × 1/12 = 83.33 ft³ = 83.33 ÷ 27 = 3.09 yd³; the rate is also 3.09 yd³ per 1,000 sq ft. Bags = 83.33 → 84.

200 sq ft at 2 inches, 1.5 cu ft bags, $40 a cubic yard. V = 200 × 2/12 = 33.33 ft³ = 1.23 yd³. Bags = 33.33 ÷ 1.5 = 22.2 → 23. Cost = 1.2346 × $40 = $49.38.

10 m² at 5 cm, 40 L bags. V = 10 × 0.05 = 0.5 m³ = 500 L. Bags = 500 ÷ 40 = 12.5 → 13.

Other questions people ask

How do I work out how much compost I need?

Multiply the area by the depth, in the same units. 1,000 sq ft at 1 inch deep is 1,000 × 1/12 = 83.3 cubic feet. Divide by 27 for cubic yards: 3.09 yd³.

How much compost should I put on a lawn or bed?

NC State Extension suggests mixing 1 to 2 cubic yards of compost per 1,000 sq ft into the top 6 to 8 inches of heavy clay or sandy soil. That is a layer about 0.3 to 0.65 inch deep before you mix it in. The calculator shows your rate in cubic yards per 1,000 sq ft to compare.

How many bags of compost make a cubic yard?

A cubic yard is 27 cubic feet, so 27 bags of 1 cu ft, 18 bags of 1.5 cu ft, or 20 bags of 40 L (764.6 L ÷ 40 = 19.1, rounded up). Type your bag size and the calculator rounds the bags up.

Is bulk or bagged compost cheaper?

Type the bulk price per cubic yard to see the bulk cost, then compare it with the bag count × the price of one bag. Remember that delivery adds to the bulk price.

How do I measure an odd-shaped bed?

Split it into rectangles and circles, work out each area, and add them. A rectangle is length × width; a circle is 3.14 × radius².

Can I use metric units?

Yes. Switch to Metric or pick the units by each box: square metres, centimetres and litres. 10 m² at 5 cm is 0.5 m³, or 500 L.