MyYardCalc
Landscaping · Material planning

Compost Calculator

Calculate the volume of compost for a garden layer or bed amendment. Estimate bulk quantity and bags from area, depth and actual package sizes.

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Your project

US & metric

Example values are filled in. Replace them with your measurements.

ft
ft
sq ft

Add other measured sections without counting overlaps twice.

sq ft
in
%

An editable purchasing margin, not a measured compaction rate.

cu ft

Use the labeled volume of the product you plan to buy.

lb / cu yd

Optional. Enter the density of this product to estimate weight.

$
$ / cu yd
$

Enter 0 if included. Bulk cost remains blank until delivery is specified.

Enter your measurements

—

The calculation

Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

  • Enter your supplier’s bulk density to show weight. Volume alone cannot determine tons.
  • 10% extra is included once. Confirm supplier minimums and delivery increments.

Saved on this device

Only estimates you choose to save are stored here.

    Measure with a little context

    How to use this compost calculator

    If compost is part of a blend, calculate the blend’s total volume and the selected compost proportion separately. This tool measures the compost layer itself.

    Choose an application depth based on the existing soil and intended use. A bag count does not set a nutrient application rate.

    Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

    A worked example

    With the example values shown below, the calculated result is 0.326 cu yd. These are demonstration inputs, not installation specifications.

    View the example measurements
    • Length / circle diameter: 12 ft
    • Width: 8 ft
    • Material depth: 1 in
    • Extra allowance: 10 %
    • Volume per bag: 1 cu ft

    From estimate to order

    Whole packages and pieces round up; measured lengths, areas and volumes keep full precision during calculation. Match the product dimensions and units to your quote, and check cuts, minimum orders and delivery before purchasing.

    Read our formulas, rounding rules and limitations →

    Compost planning questions

    How much compost do I need for a surface layer?

    Measure the area and the intended additional compost depth. For 100 sq ft at a selected half-inch depth, the geometric volume is 4.167 cubic feet before allowance. Choose a suitable rate for your soil and use; the example does not prescribe an application depth.

    Does this calculate a composting carbon-to-nitrogen ratio?

    No. This calculator estimates the volume of finished compost to buy or spread. It does not balance compost-pile ingredients, diagnose soil nutrients or determine a fertilizer rate. Keep those tasks separate from the material volume estimate.

    Calculation notes updated . Formulas, sources and limitations.

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