Mulch calculator

Mulch only works when it is deep enough: too thin and weeds push through, too thick and roots suffocate. This mulch calculator turns your bed size and depth into an exact amount.

You get:

• cubic feet and cubic yards of mulch;
• number of bags for the bag size you buy (2 cu ft is the common US bag; rubber mulch comes in 0.8 cu ft bags);
• an estimated weight if you are hauling it yourself;
• a material list with editable prices, plus optional landscape fabric.

Beds can be rectangles, circles (tree rings), triangles, or a known square footage. Switch between US units and metric at the top, and export the list to PDF or Excel. No sign-up, and everything runs in your browser.

1. Cubic feet = square feet × depth in inches ÷ 12.
2. Cubic yards = cubic feet ÷ 27.
3. Bags = cubic feet ÷ bag size (cu ft), rounded up.

A handy rule: one cubic yard covers about 108 sq ft at 3 in, 162 sq ft at 2 in, or 324 sq ft at 1 in. A 2 cu ft bag covers 8 sq ft at 3 in.

Mulch is sold by volume, not weight, so the calculator works in cubic feet and yards. Weight is shown only as a guide for hauling (shredded hardwood is roughly 500 lb per cubic yard dry, more when wet). Compost gets a 10% settling allowance; bark mulches are not compacted.

1. Front-yard beds. 30 × 10 ft = 300 sq ft at 3 in:

• 300 × 3/12 = 75 cu ft = 2.78 cubic yards;
• in 2 cu ft bags: 75 ÷ 2 = 37.5 → 38 bags;
• at 2 in deep it drops to 50 cu ft, 1.85 yards or 25 bags.

2. A tree ring. A circle 6 ft across at 4 in deep:

• area π × 3² = 28.3 sq ft;
• 28.3 × 4/12 = 9.4 cu ft = 0.35 yards;
• 5 bags of 2 cu ft.

For several identical beds, multiply the area and enter it as a known area. At around 3 yards and up, bulk delivery is usually cheaper than bags even with the delivery fee.

Typical depths:

• shrub and perennial beds: 2–3 in of shredded hardwood, pine bark or cedar;
• around trees: 3–4 in in a wide ring, but keep mulch 3–6 in away from the trunk (no "mulch volcanoes");
• dyed or decorative mulch: 2–3 in;
• vegetable beds: 1–2 in of compost or straw, renewed each season;
• playgrounds (rubber mulch): the safety depth printed by the manufacturer, often much deeper than garden beds.

Organic mulch breaks down, so most years you only need to top up about 1 in. Just enter the smaller depth to size the refresh.

Bags are clean, easy to carry and perfect for a few beds. Beyond about 3 cubic yards, bulk mulch from a landscape supplier usually costs less per yard, but it comes as a pile in your driveway and there is often a minimum order.

• Check the bag size. Most US bags are 2 cu ft, some 1.5 or 3 cu ft. Enter what is on the label.
• Weed and water first, then spread the mulch.
• Landscape fabric under mulch cuts weeding in shrub beds; skip it in perennial beds where plants spread. The material list includes it as an optional line you can delete.
• Dyed mulch: choose products with non-toxic, water-based colorants and keep it out of vegetable beds.