Mulch & Soil Calculator
Get the cubic yards, the bag count and the approximate weight for a bed at any depth — and see straight away whether bagged or bulk delivery is the cheaper way to buy it.
How to use this calculator
- Measure the bed, not the plants. For an irregular border, break it into rectangles and circles and add the results — it is far more accurate than guessing an average width.
- Choose a depth you will actually maintain. Mulch settles and decomposes, so 3 in fresh becomes about 2 in within a season. That is why 3 in is the usual target for a new bed and 1–2 in is enough for a top-up.
- Pick the material so the weight estimate is meaningful. Bark mulch and gravel differ by a factor of four in weight per yard — this decides whether your vehicle can carry it.
- Enter both prices to compare. Bagged mulch is convenient and priced per cubic foot; bulk is priced per cubic yard, which holds 13.5 of the standard 2 cu ft bags. Enter what your supplier charges and the tool says which is cheaper for your volume.
The formula
Depth is the whole game here, because it converts an area into a volume:
cubic feet = area (sq ft) × depth (in) ÷ 12
cubic yards = cubic feet ÷ 27
Bags are then ceiling( cubic feet ÷ bag volume ), and weight is estimated as cubic yards × a typical density:
| Material | Approx. lb per cu yd | Covers per yd at 3 in |
|---|---|---|
| Pine straw | 300 | 108 sq ft |
| Bark mulch, wood chips | 600 | 108 sq ft |
| Shredded hardwood mulch | 800 | 108 sq ft |
| Compost | 1,100 | 108 sq ft |
| Topsoil | 2,200 | 108 sq ft |
| Sand | 2,600 | 108 sq ft |
| Gravel, crushed stone | 2,800 | 108 sq ft |
Coverage per yard is identical for every material at a given depth — it is volume, not weight, that spreads. Weight only matters for hauling.
Worked example
A border 20 ft long and 4 ft wide, mulched 3 in deep:
- Area: 20 × 4 = 80 sq ft
- Depth in feet: 3 ÷ 12 = 0.25 ft
- Volume: 80 × 0.25 = 20 cu ft
- Cubic yards: 20 ÷ 27 = 0.74 yd³
- Standard 2 cu ft bags: 20 ÷ 2 = 10 bags
- Weight as hardwood mulch: 0.74 × 800 = about 590 lb
Ten bags fits in a car boot in two trips. Had the bed been three times bigger, you would be at 2.2 cubic yards — 30 bags, about 1,800 lb — and a bulk delivery starts to look sensible.
Bags per cubic yard
| Bag size | Bags per cubic yard |
|---|---|
| 3 cu ft | 9 |
| 2 cu ft (most bagged mulch) | 13.5 |
| 1.5 cu ft | 18 |
| 1 cu ft (bagged soil) | 27 |
| 0.75 cu ft | 36 |
Frequently asked questions
How many bags of mulch are in a cubic yard?
Thirteen and a half bags of the standard 2 cubic foot size, because a cubic yard is 27 cubic feet. If your bags are 3 cubic feet it is 9 bags per yard, and for 1.5 cubic foot bags it is 18.
How deep should mulch be?
Two to three inches for most beds. That is enough to suppress weeds and hold moisture while still letting water and air through. Deeper than about four inches starts to starve roots of oxygen and can keep the soil surface too wet. For a top-up over existing mulch, one to two inches is plenty.
How much area does a cubic yard of mulch cover?
About 108 square feet at 3 inches deep, 162 square feet at 2 inches, and 324 square feet at 1 inch. Coverage depends only on depth, not on which material you spread.
How much does a yard of mulch weigh?
Roughly 600 to 800 pounds dry for typical bark or shredded hardwood mulch, and noticeably more when it is soaked with rain. Topsoil is about 2,200 pounds per yard and gravel closer to 2,800, so check your vehicle payload before hauling either.
Is bulk mulch cheaper than bags?
Usually from around three cubic yards up, where the price per cubic foot in bulk is well under the bagged price and one delivery replaces forty bags. Below about one yard bags normally win once delivery fees are counted. Enter both prices in the calculator to compare for your own volume.
Guides
- How Deep Should Mulch Be?
- Bulk or Bagged Mulch: Which Is Actually Cheaper?
- When Should You Mulch? Spring, Fall, and Why Timing Matters
- Mulch Types Compared: Hardwood, Bark, Cedar, Straw and Rubber
- How Much Topsoil Do I Need?