Mulch Calculator — cubic yards and bags (no fake tonnage)
Enter your bed area and the depth of mulch you want. You get cubic yards and bags — and an honest explanation of why no weight is shown.
Mulch is the most commonly miscalculated landscaping material, and it is almost always miscalculated in the same direction: people order too little, because they work out the volume of the bed rather than the volume of mulch they actually need after settlement and offcuts.
There is a second trap. Search for a mulch calculator and you will usually be offered a tonnage as well as a volume — which implies somebody knows how much a cubic yard of bark mulch weighs. They do not. We went looking for that number and established that it does not exist in any authoritative source: Cornell's composting handbook lists bark rows with the bulk-density column literally empty, a full-text search of NIST Handbook 133 returns nothing, and the mulch industry in the United States is regulated and traded by volume, not by weight.
So this calculator gives you volume, bags and cost, and tells you plainly that there is no weight to give. If you are buying by weight rather than volume, ask your supplier for the density of the actual product — that figure exists, it is just not published anywhere universal.
A worked example you can check by hand
A 20 ft × 10 ft area at 2 in deep,
with a 5% waste allowance:
Area
200 ft² (20 ft × 10 ft)
Depth
2 in = 0.1667 ft
Volume (before waste)
33.3333 ft³
Waste allowance
5%
Volume (with waste)
35 ft³ = 1.2963 yd³
Weight
not calculated — this product is sold by volume (see below)
How we calculate this — and every number we used
We do not use a hidden "magic number". Here is the entire calculation:
volume = area × depth
volume_with_waste = volume × (1 + waste%)
Why the calculation stops there. There is no third line, because
converting volume to weight needs a density and no authoritative density exists for this product.
Rather than borrow another material's figure, we stop at volume — which is how this product is
bought and sold anyway.
Bark mulch — sold by volume (no authoritative density exists)
State
loose, as delivered
Moisture basis
as-delivered
Sold by
volume — no weight is givenwe could not find any authoritative density for this product
Last reviewed
2026-09-13
Why we do not give a weight
We could not find any authoritative bulk density for bark mulch, and we established that the absence is institutional rather than a search failure: (a) the Cornell On-Farm Composting Handbook Table A.1 lists bark-hardwood and bark-softwood rows with the bulk-density column left literally empty; (b) a full-text search of NIST Handbook 133 (254 pages) returned no mulch density figure; (c) the Mulch & Soil Council confirms the US mulch industry is regulated and traded BY VOLUME, not by weight. We therefore give volume only and do NOT substitute wood chips, which are a different product.
This calculator is only valid under these assumptions. If any of them do not match your project,
treat the result as a rough guide and get a quote from your supplier.
Beds are measured as rectangles. For curved beds, measure the longest and widest points and accept a slight over-estimate, or split the bed into rectangles.
Depth is the settled depth of mulch on the bed, not the depth of a loose heap.
The product is bark mulch. Wood chips, arborist chips, straw and compost are different materials with different coverage characteristics.
This calculator gives volume only. It deliberately does not convert to tonnes — see the explanation on the page.
It does not include bed edging, weed fabric, or the cost of labour.
Frequently asked questions
How much mulch do I need?
Multiply the bed area by the depth you want. Most beds want 2 to 3 inches; 3 inches gives good weed suppression. A 200 square foot bed at 3 inches needs about 1.9 cubic yards before any waste allowance.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes 27 bags of 1 ft³, 18 bags of 1.5 ft³, 14 bags of 2 ft³ or 9 bags of 3 ft³. Bulk delivery is usually much cheaper above about 2 cubic yards.
How much does a cubic yard of mulch weigh?
We do not publish a figure, because no authoritative source does. Cornell's composting handbook has empty bulk-density cells for bark, NIST Handbook 133 contains no mulch density, and the US industry sells mulch by volume rather than weight. Any site quoting you a precise tonnage for bark mulch is quoting a number that came from somewhere other than a standard.
Can I use the wood chip figures instead?
No. Wood chips and bark mulch are different products: bark is lighter and breaks down differently, and commercial bark mulch often contains a large proportion of wood fibre, so the two do not interchange. We publish wood chip density separately, for wood chips.
How deep should mulch be?
Two to three inches is the usual recommendation for weed suppression and moisture retention, which matches the guidance from Clemson University's Home & Garden Information Center. More than about 4 inches can starve roots of oxygen. Keep mulch clear of trunks and stems.
Should I add extra for settlement?
Yes, a little. Mulch settles as it weathers, and beds are rarely exactly rectangular. We default to a 5% allowance, which is enough for a tidy bed and not enough to waste money.