Compost Calculator

Enter the size of the bed or lawn and a depth and get the compost to order in cubic yards, tons or bags, rounded up once, with the working shown for a thousand square feet at one inch.

A ready-made setup of the Raised Bed Soil Calculator.

Estimates for planning, not professional advice. Read the full notice.

Bed or lawn size

Feet and inches, like 12' 6"

Feet and inches, like 12' 6"

Inches, like 4 in

Example: a thousand square feet of lawn

3.5 yd³ to order (3.09 yd³ exact)

  • Volume in the area 83.33 ft³
  • Cubic yards to order 3.09 yd³
  • Cubic yards at the supplier's step 3.5 yd³
  • Tons at the weight above 1.5 tons
  • Tons at the supplier's step 2 tons

Shopping list

Example: a thousand square feet of lawn
ItemSizeBuy
Compost by the cubic yard1 yd³3.5 yd³

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    Worked example: a thousand square feet of lawn

    Show the working
    1. Area 25 ft × 40 ft = 1,000 ft²
    2. Volume at the depth 1,000 ft² × 1 in = 83.33 ft³
    3. Add the waste allowance, once 83.333333 ft³ + 0 % waste = 83.33 ft³
    4. Cubic yards: divide by the cubic feet in a yard 83.333333 ft³ ÷ 27 ft³ in a yd³ = 3.09 yd³
    5. Round up once, to the supplier's yard step 3.09 yd³ = 3.5 yd³

    Assumptions

    The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.

    Compost weight 1,000 lb/yd³[1]
    Default Oregon State Extension's rule of thumb for screened compost at 50 percent moisture; very wet compost can exceed 1,500.
    Landscape waste or overage 0%
    Default No silent overage. Check your label or supplier.
    Supplier's smallest yard step 0.5 yd³
    Default Suppliers sell bulk in steps. Check your label or supplier.
    Supplier's smallest ton step 1 ton
    Default Suppliers sell by the ton in steps. Check your label or supplier.
    Compost bag size 1 ft³
    Default Bag sizes are on the label. Check your label or supplier.
    Compost topdressing, Penn State Extension 0.25 in[2]
    Penn State Extension: compost used as a topdressing goes on as a thin layer, about 1/4 inch, and a one-inch layer is approximately 3.1 cubic yards per 1000 square feet.

    Compost for a thousand square feet, by depth

    Cubic yards and bags of compost for a lawn or bed of a thousand square feet at each depth

    DepthCubic yardsCubic yards at the supplier's stepBags of 1 ft³
    1/4 in 0.77 yd³1 yd³21 bags
    1/2 in 1.54 yd³2 yd³42 bags
    1 in 3.09 yd³3.5 yd³84 bags
    2 in 6.17 yd³6.5 yd³167 bags

    Each depth is worked out on its own, with no waste allowance. The thin depths are the ones topdressing is written in.

    What Penn State Extension says about topdressing

    Topdressing depth and the volume of a one-inch layer, as Penn State Extension prints them

    FigurePenn State Extension
    Thin topdressing layer 0.25 in
    A one-inch layer, per thousand square feet 3.1 yd³/1000 ft²

    Source: [2]

    The page is about turf. Both figures are the extension's own words; the calculator uses the depth you type.

    Questions

    How much compost do I need for a lawn?

    Enter the lawn size and the depth you will spread. The table shows a thousand square feet at four depths, and the calculator rounds your own area up once to the supplier's yard step.

    How much compost does a raised bed take?

    A raised bed is filled with a mix of soil and compost rather than compost alone. The raised bed soil calculator splits the volume by a published recipe.

    How deep is a compost topdressing on a lawn?

    Penn State Extension describes a thin topdressing layer and gives the volume of a one-inch layer; both are quoted in the second table with their source. The depth in the calculator is yours to set.

    Sources (2)
    1. Interpreting Compost Analyses (EM 9217), Oregon State University Extension Service, published October 2018, reviewed 2023. Code or government
      “As a rule of thumb, screened composts that contain 50% moisture will have a bulk density of about 1,000 lb/cu yd. Very wet composts can have a bulk density of over 1,500 lb/cu yd.”
      Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used
    2. Using Composts to Improve Turf Performance, Penn State Extension, web article dated January 1, 1997. Code or government
      “When applying compost as a topdressing, it is important to apply a thin layer (about ¼ inch) and work it into the soil.”
      “composts are applied to the soil surface at a rate between a one-inch layer (approximately 3.1 cubic yards per 1000 ft²)”
      Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used

    These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.

    Sources

    • [1] Oregon State University Extension Service, Interpreting Compost Analyses (EM 9217). Checked November 12, 2026. https://extension.oregonstate.edu/catalog/pub/em-9217-interpreting-compost-analyses
    • [2] Penn State Extension, Using Composts to Improve Turf Performance. Checked November 12, 2026. https://extension.psu.edu/using-composts-to-improve-turf-performance

    Made with HoneyDoMath.com. Estimates for planning; check product labels and local codes before you buy or build.