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Mulch Calculator

Work out how many bags or cubic yards of mulch a bed needs, at the depth that actually suppresses weeds.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Mulch required

27 bags

High confidence

Bag counts round up — you cannot buy part of a bag, and the last bag is usually the one that finishes the edges.

Volume
1.96 yd³
Cubic yards
1.96 yd³
Litres
396.26 gal
Approximate weight
1322.77 lb

With the figures above, the mulch required comes to 27 bags. Note that bed area sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • 75-100 mm (3-4 in) mulch depth for weed suppression and moisture retention — university extension horticulture guidance
  • Bagged mulch is commonly sold in 2 ft³ (56.6 L) bags in North America and 50-70 L bags elsewhere

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

How deep should mulch be?
75-100 mm, or three to four inches. Below 50 mm weeds push straight through and the moisture benefit largely disappears. Above 100 mm you start to restrict oxygen at the root zone, which on a heavy soil does more harm than the weeds would have.
Should mulch touch the trunk?
No. Piling mulch against a trunk — the 'mulch volcano' — holds moisture against the bark, invites rot and encourages roots to grow into the mulch instead of the soil. Pull it back 75-100 mm from the stem of anything woody.
How often does mulch need topping up?
Organic mulch breaks down, which is the point of it — it feeds the soil. Expect to add 25-50 mm annually to hold the depth. Bark lasts longer than wood chip; both outlast straw by a wide margin.
Bags or bulk?
Bulk is cheaper per unit above roughly two cubic yards, and that is about twenty-seven 2 ft³ bags. Below that the delivery charge and the need to move a loose pile usually outweigh the saving — and bags can be carried through a house, which a tipped load cannot.