Mulch Calculator
Calculate how much mulch you need for garden beds. Get cubic yards, 2 cu ft bags and a cost estimate from bed dimensions and depth.
Mulch needed
1.94 cu yd
- Volume
- 52.5 cu ft
- 2 cu ft bags
- 27
- Estimated material cost
- $121.50
One cubic yard equals 27 cubic feet, or about 13.5 bags of 2 cu ft mulch.
Mulch is sold in 2 cubic foot bags at garden centers and by the cubic yard in bulk. This calculator converts bed dimensions and depth into both, so you can compare the price of bags against a bulk delivery.
Two to three inches is the sweet spot for most beds: enough to suppress weeds and hold moisture without smothering roots. Keep mulch a few inches away from siding, tree trunks and foundations.
How the mulch calculator works
Volume in cubic feet = length × width × depth, with depth converted to feet. Add the waste allowance, divide by 27 for cubic yards, then divide by the bag size to get the bag count. One cubic yard is 27 cubic feet.
Worked example
A 10 × 20 ft bed at 3 inches deep is 50 cu ft, or 1.85 cu yd — about 25 bags of 2 cu ft mulch. With 5% waste, plan on 1.94 cu yd or 27 bags.
How deep should mulch be?
Two to three inches is enough for most beds. It suppresses weeds, slows evaporation and keeps the soil temperature steadier without starving roots of oxygen.
Go thinner — about one inch — around shallow-rooted plants, and keep mulch several inches away from tree trunks, shrubs and the siding. Piling mulch against stems holds moisture and invites rot.
Bulk vs bags
| Option | Best for | Notes |
|---|---|---|
| 2 cu ft bags | Small beds, touch-ups | 13.5 bags per cubic yard |
| 3 cu ft bags | Medium beds | 9 bags per cubic yard |
| Bulk by the yard | Large beds, 3+ yards | Cheaper per yard; delivery fee |
| Bulk by the truckload | Very large projects | Confirm the actual volume |
Common mulch mistakes
- Building mulch volcanoes around trees, which traps moisture against the trunk.
- Spreading less than an inch and expecting weed control.
- Using fresh, uncomposted mulch against young plants.
- Putting plastic sheeting under mulch; it blocks water and air.
- Forgetting that mulch settles and breaks down, so the bed needs topping up each year.
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cu ft mulch. Bulk mulch is usually sold by the yard and is cheaper once you need more than about 2–3 cubic yards.
How deep should mulch be?
Two to three inches is right for most garden beds. One to two inches is enough around shallow-rooted plants, and more than four inches can restrict oxygen and water movement into the soil.
How often should I add mulch?
Organic mulch breaks down over time. Top up once or twice a year, usually in spring, to maintain a 2–3 inch layer. Remove old mulch only if it has matted into a water-blocking layer.
Is bulk mulch cheaper than bags?
Bulk is usually cheaper per cubic yard once you need more than 2–3 yards, but delivery fees and minimum orders can erase the savings on small jobs. Compare the delivered price, not just the unit price.
Should I put mulch against the house?
Keep mulch at least 6 inches away from siding and 12 inches from the foundation to reduce moisture and termite risk. A thin layer is fine, but do not pile it above the siding's bottom edge.
Is rubber mulch a good choice?
Rubber mulch lasts much longer and does not decompose, but it costs more upfront, can get hot in full sun and does not add organic matter to the soil. It is most useful in high-traffic play areas.
Assumptions and accuracy
- Dimensions are converted to feet before the calculation; 1 ft = 12 in = 0.3048 m.
- Waste allowances are estimates. Add more for irregular shapes, many cuts and uneven subgrade.
- Bag yields, coverage rates and material densities vary by product. Check the label or ask your supplier.
- Local building codes and site conditions always take precedence over a general-purpose calculator.
- Read our full methodology