Mulch coverage, metric units and why yards are not tons
Mulch can be quoted in cubic feet, cubic yards, litres, cubic metres, bags, or weight. The first four describe volume. A bag is only useful for comparison when its labelled contents are known, and weight introduces a separate material-density question. Keep these distinctions visible before converting a supplier's quote.
Calculate the area one bag will cover
Coverage area equals volume divided by depth in matching units. A 2-cubic-foot bag spread at 3 inches, or 0.25 foot, covers 2 ÷ 0.25 = 8 square feet. At 2 inches it covers 12 square feet; at 4 inches it covers 6. Those are geometric coverage figures before any allowance or irregular spreading.
A cubic yard contains 27 cubic feet. At 3 inches deep, it covers 108 square feet. Colorado State Extension publishes the same 108-square-foot coverage at this depth. The depth is essential: a cubic yard does not have a single coverage area independent of how it is spread.
Work directly in metric when the bag is metric
A bed 5 metres by 4 metres has an area of 20 square metres. At a selected 7.5-centimetre added depth, convert the depth to 0.075 metre. Volume is 20 × 0.075 = 1.5 cubic metres, or 1,500 litres. If you choose a 5% allowance, the adjusted amount is 1,575 litres.
Fifty-litre bags would require 1,575 ÷ 50 = 31.5, rounded up to 32 bags. Those contain 1,600 litres, leaving 25 litres beyond the allowance-adjusted estimate. A bag marked 50 kilograms does not establish the same volume as a 50-litre bag.
Convert the volume, not just the label
One cubic yard is approximately 0.764555 cubic metre. One cubic foot is approximately 28.3168 litres. These values follow the international length definitions used in NIST's conversion tables. A nominal 2-cubic-foot bag therefore represents about 56.63 litres; it is not exactly the same size as a 50-litre package.
For purchasing, calculate the requirement in one consistent volume unit, convert the labelled bag size into that unit, then divide and round up. Do not round every conversion early. Repeated rounding can change the result near a whole-bag boundary.
Ask for density when a quote uses weight
There is no universal conversion from a cubic yard of mulch to a ton. Material type, moisture, and how it is packed can change the relationship. If a supplier provides an applicable bulk density, the arithmetic is mass = volume × density. Record the source and conditions of that density instead of adopting a generic number from an unrelated material.
For example, a purely hypothetical supplied density of 250 kilograms per cubic metre would turn 1.5 cubic metres into 375 kilograms. A different density would produce a different mass for the same volume. This example is not a transport-weight recommendation. Confirm the actual load and equipment limits with the supplier before collecting material.
Put the example to work
Open the mulch calculator and replace the example values with your own measurements. Keep the assumptions and result together using Download CSV or Print.
Sources & further reading
Source material checked November 9, 2026. This guide is an original explanation; source publishers do not endorse this website.