How the Gravel & Mulch Calculator Works
This page converts a measured project area and material depth into cubic feet, cubic yards, estimated weight, 0.5 cubic-foot bag count, and optional cost. Rectangle, circle, triangle, and direct-area modes all feed the same volume formula: volume in cubic feet = area in square feet x depth in feet. Cubic yards are then calculated by dividing cubic feet by 27.
The calculator also multiplies cubic feet by the selected density to estimate pounds and tons. Those density values are planning averages, not vendor guarantees. Mulch, topsoil, sand, gravel, and decomposed granite can vary with moisture, compaction, screen size, and local supplier mix.
Worked Example
A 12 ft by 10 ft bed has 120 square feet of area. At a 3 inch depth, the depth is 0.25 feet, so the volume is 120 x 0.25 = 30 cubic feet. Divide by 27 to get 1.11 cubic yards. With pea gravel at 95 lb per cubic foot, the weight estimate is 2,850 lb, or about 1.43 tons. At $40 per cubic yard, the material estimate is $44.44 before delivery, tax, edging, fabric, or installation.
Use the Results for Ordering
Bulk yards are usually easiest for large beds, paths, and driveway refreshes. Bag counts are useful for small touch-ups or when a delivery truck cannot reach the work area. For paths, drainage areas, and patios, confirm the base, compaction, and edging plan separately because this calculator only models the surface layer you enter.
Project Notes
| Input or output | How to use it | Common adjustment |
|---|---|---|
| Area | Measure the actual footprint that will receive material. | Break irregular beds into rectangles or use direct-area mode. |
| Depth | Enter finished loose depth in inches. | Use thicker lifts for stone bases only when the base design calls for it. |
| Density | Choose the closest material or enter a supplier density. | Increase the allowance for wet or compacted material. |
| Cost | Enter the quoted price per cubic yard. | Delivery fees, pallets, minimum orders, and taxes are separate. |
Common Mistakes
- Using inches as feet: three inches is 0.25 feet, not 3 feet.
- Forgetting settlement: mulch and topsoil may settle after watering; gravel may compact during leveling.
- Ignoring edging: loose material spreads without a border, especially on slopes and path edges.
- Digging before utility marking: call or file an 811 request before soil-disturbing work such as edging, post holes, and trenching.