Mulch, Soil, Rock & Gravel Calculator
Free bulk material calculator for mulch, soil, sand, gravel, and rock. Get cubic feet, cubic yards, liters, approximate tons, bag counts, and cost.
This calculator converts an area’s length, width, and depth into the volume of bulk material you need — mulch, topsoil, sand, gravel, or rock. It reports cubic feet, cubic yards, and liters, the number of 2 ft³ or 3 ft³ bags and their cost, and the approximate weight in tons and pounds based on the material’s density.
How the volume is worked out
- Depth is entered in inches and converted to feet by dividing by 12.
cubic feet = length × width × (depth ÷ 12)cubic yards = cubic feet ÷ 27, andliters = cubic feet × 28.3168- Bag counts round up:
2 ft³ bags = cubic feet ÷ 2and3 ft³ bags = cubic feet ÷ 3, each multiplied by the price per bag. - Weight uses the chosen material’s density:
tons = cubic yards × density, andpounds = tons × 2000.
There is no waste field here, so the volume shown is the volume you asked for. If your bed edges are irregular or the grade dips, round the bag count up rather than down.
Worked example: a 20 × 10 ft bed at 3 inches
Defaults: length 20 ft, width 10 ft, depth 3 in, price $4 per bag.
| Step | Calculation | Result |
|---|---|---|
| Depth in feet | 3 ÷ 12 | 0.25 ft |
| Cubic feet | 20 × 10 × 0.25 | 50 ft³ |
| Cubic yards | 50 ÷ 27 | 1.85 yd³ |
| Liters | 50 × 28.3168 | 1,415.84 L |
| Weight (mulch, 0.4 t/yd³) | 1.85 × 0.4 | 0.7 tons (1,481 lb) |
| 2 ft³ bags | 50 ÷ 2 = 25, at $4 each | 25 bags, ~$100 |
| 3 ft³ bags | 50 ÷ 3 = 16.67, round up | 17 bags, ~$68 |
At 1.85 cubic yards, bulk delivery usually beats bagged mulch on price, but bags win for a single small bed where the delivery minimum would swamp the saving.
Reference: depth, coverage, and bag counts
Coverage per cubic yard is 324 ÷ depth in inches, since 27 ft³ spread over a given depth covers that many square feet.
| Depth | Coverage per yd³ | Volume per 100 ft² | 2 ft³ bags per 100 ft² | 3 ft³ bags per 100 ft² |
|---|---|---|---|---|
| 1 in | 324 ft² | 8.3 ft³ | 5 | 3 |
| 2 in | 162 ft² | 16.7 ft³ | 9 | 6 |
| 3 in | 108 ft² | 25.0 ft³ | 13 | 9 |
| 4 in | 81 ft² | 33.3 ft³ | 17 | 12 |
| 6 in | 54 ft² | 50.0 ft³ | 25 | 17 |
The exact coverage at 3 inches is 108 ft² per cubic yard; many suppliers quote a round 100 ft² to leave room for settling and a thin edge.
Material densities and weight
Volume is the same for any loose fill, but weight is not. The calculator uses a density of 0.4 tons per cubic yard for mulch, 1.1 for topsoil, 1.35 for sand, 1.4 for gravel, and 1.6 for rock or riprap. Those are planning averages: moisture and grading move them by 10–20%, which matters when you order by weight or check a delivery limit.
| Material | Density (tons/yd³) | Coverage per yd³ at 3″ |
|---|---|---|
| Mulch | 0.4 | ~108 ft² |
| Topsoil | 1.1 | ~108 ft² |
| Sand | 1.35 | ~108 ft² |
| Gravel | 1.4 | ~108 ft² |
| Rock / riprap | 1.6 | ~108 ft² |
Coverage depends only on depth, not on the material: a cubic yard spread 3 inches deep covers about 108 ft² whatever you are spreading. Depth is the lever, so a driveway at 4 inches needs more per square foot than a garden bed at 2.
Bags or bulk?
Bagged mulch is convenient and easy to carry, but it usually costs two to three times as much per cubic foot as bulk. A cubic yard of bulk mulch is 13 to 14 two-cubic-foot bags, so the comparison is simple: multiply the bag price by 14 and set it against the delivered yard price. Bulk wins on larger beds, while bags make sense for a single shrub or a small top-up.
Common mistakes
- Feeding depth in feet. The field expects inches, and the calculator does the ÷12 for you. Enter 3, not 0.25.
- Going too shallow. A 1-inch layer looks sparse and barely suppresses weeds. Two to three inches is the working range for beds.
- Ignoring settling. Fresh mulch and compost compact by roughly 10–15% in the first season, so a small surplus is normal.
- Comparing bag price to bulk without the bag count. Multiply the bag count by price before deciding; a yard of mulch is 13–14 two-cubic-foot bags.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 ft³, which is 14 bags of 2 ft³ or 9 bags of 3 ft³ once you round up.
How deep should mulch be around plants?
Two to three inches for general beds. Keep it pulled back a few inches from trunks and stems, and use a thinner layer over shallow-rooted groundcovers.
Can I use this for topsoil or compost?
Yes. The volume math is the same for any loose fill; only the price per bag and the bulk density change.
How much does a cubic yard of mulch cover?
At 3 inches deep, about 108 ft²; at 2 inches, about 162 ft²; at 1 inch, about 324 ft². Many suppliers round the 3-inch figure to 100 ft² to allow for settling.
If the bed is a raised box, the board-foot calculator prices the frame that holds it, and for a concrete pad instead of loose fill, the concrete calculator works in cubic yards the same way.