Mulch Calculator
Enter the length, width and depth of each bed and this calculator tells you exactly how much mulch to buy — the number of bags, the order in cubic yards and cubic feet, the estimated weight, and the cost. Everything runs in your browser; nothing you type leaves your device.
It is built for mulch specifically. Pick a mulch type (hardwood bark, pine, cedar, dyed, wood chips, rubber, straw or compost) and it pre-fills a typical depth, density and bag size; tap a recommended-depth chip for new beds, an annual top-up, weed suppression or a playground; add a tree ring around a trunk; and compare buying by the bag against ordering in bulk. Every number stays editable.
Add a bed for each area and the totals update live. Switch between metric and imperial at any time and every value converts in place, or switch to Coverage mode to work backwards from mulch you already have.
How to use the mulch calculator
Mulch coverage is a footprint area multiplied by a depth. You can mix units — measure the bed in feet and set the depth in inches — and the calculator handles the conversion, which is the step most people get wrong by hand.
Choosing a mulch type only sets sensible defaults for density and bag size; it never changes the covered area or the volume, because coverage is pure geometry.
How to calculate mulch in 5 steps
- Choose unitsPick metric (m, mm, m³) or imperial (ft, in, yd³) at the top. You can switch later and every entry converts in place.
- Pick a mulch typeChoose hardwood bark, pine, cedar, dyed, wood chips, rubber, straw or compost to pre-fill a typical density, depth and bag size. The type changes only the weight and bag convention, never the covered area — every value stays editable.
- Set the depthTap a recommended-depth chip — new bed 3 in, annual top-up 2 in, weed suppression 4 in, tree ring 3 in, or a playground depth — or type your own. Chips fill any empty bed depths without overwriting depths you have typed.
- Add your bedsAdd a bed per area, choose its shape (rectangle, circle, triangle, area or tree ring) and enter the dimensions. Totals sum across every bed.
- Read the resultsThe panel shows bags and order volume as the two headline numbers, plus cubic feet, estimated weight, truckloads and cost. Enter both a bag price and a bulk price to see which is cheaper. Export CSV or print a plan.
Worked example: a 10 × 10 ft bed, 3 in deep
The classic question is “how much mulch for a 10 by 10 bed at 3 inches?”. Convert the depth to feet first, multiply by the footprint, then divide by 27 — there are 27 cubic feet in a cubic yard — or divide the cubic feet by the bag size to count bags.
10 ft × 10 ft × 3 in = 0.93 yd³ (25 ft³ · 13 bags of 2 cu ft)
- Footprint area: 10 ft × 10 ft = 100 ft²
- Depth in feet: 3 in ÷ 12 = 0.25 ft
- Cubic feet: 100 ft² × 0.25 ft = 25 ft³
- Cubic yards: 25 ft³ ÷ 27 = 0.93 yd³
- Bags: 25 ft³ ÷ 2 = 13 bags (round up)
How mulch depth changes what you order
Depth is the biggest lever on a mulch order: going from a 2 in annual top-up to a 4 in weed-suppressing layer doubles the volume and the number of bags for the same bed. Two to three inches suits most established beds; four inches suppresses weeds; playground mulch is much deeper for fall protection.
How much does a yard of mulch cover?
Coverage is pure geometry: one cubic yard is 27 cubic feet, so spread at a given depth it covers 324 ÷ depth-in-inches square feet — the same whichever mulch you choose. Use this table to sanity-check an order or to estimate the depth a fixed amount will give you.
| Depth | Covers (ft²) | Covers (m²) |
|---|---|---|
| 1 in | 324 | 30.1 |
| 2 in | 162 | 15.1 |
| 3 in | 108 | 10.0 |
| 4 in | 81 | 7.5 |
| 6 in | 54 | 5.0 |
How many bags of mulch are in a cubic yard?
Bagged mulch is sold by the cubic foot, so the bags in a cubic yard is 27 divided by the bag size. A standard 2 cu ft bag is 13.5 per yard exactly — you buy 14 to fill a full yard — and once a job needs many bags, ordering the same volume in bulk is usually cheaper.
A 2 cu ft bag is 13.5 bags per cubic yard exactly — buy 14 to fill a full yard.
How much mulch for a tree ring?
A tree ring is a doughnut, not a full circle: you mulch the ring between the outer edge and a clear gap around the trunk. Choose the Tree ring shape, enter the outer diameter and the trunk clearance, and the calculator mulches only the ring — the trunk hole is never counted. Keep mulch 2–3 in clear of the trunk so you don’t build a “mulch volcano” that rots the bark.
6 ft ring, 1 ft trunk clearance, 3 in deep = 27 ft² mulched · 0.25 yd³ · 4 bags
Frequently asked questions
How much mulch do I need?
Measure the length and width of each bed and pick a depth — 2 to 3 inches suits most beds. Enter them (you can use feet for the bed and inches for the depth) and the calculator multiplies them, adds your waste allowance and totals every bed into one order in bags, cubic yards and cubic feet. Add a bed for each separate area.
How many bags of mulch are in a cubic yard?
Divide 27 cubic feet by the bag size: a 2 cu ft bag is 13.5 per yard exactly, so you buy 14 to fill a full cubic yard; a 1 cu ft bag is 27, and a 0.8 cu ft rubber bag about 34. The calculator counts bags by rounding your exact order up to whole bags for the bag size you pick.
How deep should mulch be?
Two to three inches is right for most established beds — enough to suppress weeds and hold moisture without smothering roots. Use up to four inches for heavy weed suppression, top up an existing bed by about two inches a year, and keep mulch a couple of inches clear of stems and trunks. Playground mulch is much deeper (six inches or more) for fall protection — always check your local safety code.
Should I buy mulch in bags or in bulk?
Bags are convenient for small beds and easy to carry; bulk (by the cubic yard, delivered) is usually cheaper once a job runs to many bags. Enter a bag price and a bulk price and the calculator shows both totals, tells you which is cheaper and by how much, and can show the break-even volume where bulk overtakes bags.
How much area does a yard of mulch cover?
It depends only on depth: one cubic yard covers 324 ÷ depth-in-inches square feet. That is about 162 ft² at 2 in, 108 ft² at 3 in and 81 ft² at 4 in — the same for any mulch. Switch to Coverage mode to enter a volume or a number of bags and read the area covered directly.
How much mulch do I need for a tree ring?
A tree ring is a ring, not a full circle, so only the band around the trunk is mulched. Choose the Tree ring shape and enter the outer diameter and the trunk clearance; the calculator mulches the area between them and never counts the trunk hole. A 6 ft ring with a 1 ft clearance at 3 in takes only about a quarter of a cubic yard.
Which mulch lasts the longest?
Among wood mulches, cedar and cypress last longest (two to three years) thanks to natural oils, followed by pine bark and wood chips (one to two years), with shredded hardwood and dyed mulch breaking down fastest (about a year). Straw lasts less than a season and compost decomposes as it feeds the soil, while rubber mulch does not decompose at all.
Is rubber mulch worth it?
Rubber mulch lasts 10+ years and does not decompose, which is why it is popular for playgrounds and long-term beds — but it is far heavier and is sold in smaller bags (about 0.8 cu ft), so pick “Rubber mulch” and the calculator uses the right density and bag size and shows weight alongside volume. It never enriches soil the way wood or compost does.
Does it work in metric and imperial?
Both. Switch units at the top and every dimension, volume, weight and price converts in place — depths in inches or millimetres, volume in cubic yards or cubic metres. You can measure a bed in feet and set the depth in inches; the calculator handles the mix.
Is the calculator private?
Yes. Every calculation runs entirely in your browser. Nothing you enter is sent to any server, and your project is saved only in your own browser's local storage.