Turn a square footage into a volume
Enter the area you're covering and how deep the material needs to go, and get the volume in cubic feet and cubic yards — plus how many bags to order.
How much mulch, soil, or gravel do I need?
Volume is area times depth. If you're covering 120 sq ft at a 3-inch depth, that's 120 × 0.25 ft (3 inches converted to feet) = 30 cubic feet. The calculator above does that conversion for you — just enter the depth in inches or feet, whichever is easier to measure.
Bulk suppliers usually sell mulch, soil, and gravel by the cubic yard, while bagged material at a hardware store is priced by cubic feet per bag — commonly 2 cubic feet. That's why both units, plus a bag count, are shown together above.
Don't have your square footage yet? Calculate it from length and width first →
Recommended depths by material
| Material | Typical depth | Notes |
|---|---|---|
| Mulch (new bed) | 3 in | 2 in is enough for a yearly top-up |
| Topsoil | 4–6 in | Deeper for new lawns or raised beds |
| Gravel path | 2–4 in | Add a compacted base layer beneath |
| Sand (paver base) | 1 in | Sits under pavers, not a standalone layer |
| Concrete slab | 4 in | 6 in for driveways carrying vehicle weight |
Common questions
Why do suppliers sell by the cubic yard instead of cubic feet?
A cubic yard is 27 cubic feet, and bulk deliveries of mulch, soil, or gravel are large enough that cubic yards keep the numbers manageable. Bagged material at a hardware store is small enough that cubic feet make more sense.
Should I round up when ordering material?
Yes — settling, uneven ground, and spillage typically eat 10% of your total. If the calculator says 30 cubic feet, plan on closer to 33.
How is this different from the square feet calculator?
The square feet calculator gives you area — a flat measurement with no depth. This page takes that area and a depth to give you volume, which is what you actually need to order material.