How to Calculate Gravel Needed for a Project
Area × depth, adjusted for the specific material's density
Volume first: area × depth
Like a concrete slab, gravel volume starts with area (length × width) times depth, converted to cubic feet or cubic yards. Depth depends on the use — a decorative top layer is thin and a base under a driveway or slab much deeper — so take it from your plan, your supplier or the product you are covering.
Converting volume to weight
Suppliers often sell gravel by the ton. The U.S. Army and Marine Corps earthmoving manual (TM 3-34.62) lists dry gravel at 2,700–3,000 lb per loose cubic yard (about 1.35 to 1.5 tons) and dry sand at 2,600–2,900 lb. The Gravel Calculator uses about 1.42 tons per cubic yard for gravel. Ask your supplier for the figure for the stone you are buying.
Compaction
Loose gravel takes up less room once compacted. TM 3-34.62 gives a loose-to-compacted factor of 0.86 for sand or gravel, so if your depth is the finished, compacted depth, divide the compacted volume by 0.86 — about 16% more — to get the loose volume to order. The Gravel Calculator's 10% default allowance covers spreading loss; raise it if you entered a compacted depth.
Gravel per 100 square feet
The table shows the volume and approximate weight for 100 ft² at common depths. Multiply by your area in hundreds of square feet.
| Depth | Cubic yards | Tons at 1.42 t/yd³ |
|---|---|---|
| 2 in | 0.62 | 0.87 |
| 3 in | 0.93 | 1.31 |
| 4 in | 1.23 | 1.75 |
| 6 in | 1.85 | 2.62 |
Worked Example
A 10 ft × 50 ft path, 3 inches deep, at the Gravel Calculator's density of about 1.42 tons per cubic yard.
Volume: 10 × 50 × (3 ÷ 12) = 125 ft³ = 4.63 yd³
Weight: 4.63 × 1.42 ≈ 6.6 tons
With a 10% allowance: about 5.1 yd³, or 7.2 tons
FAQ
- How many tons of gravel are in a cubic yard?
- TM 3-34.62 lists dry gravel at 2,700–3,000 lb per loose cubic yard, about 1.35 to 1.5 tons. The Gravel Calculator uses about 1.42 tons; your supplier's figure for the exact stone is best.
- How much gravel do I need for 100 square feet?
- At 3 inches deep, 100 ft² needs 100 × 3 ÷ 12 = 25 ft³, or 0.93 cubic yards, about 1.3 tons. At 4 inches it is 1.23 cubic yards.
- Should I order for the loose or the compacted depth?
- Order loose material. If your depth is the finished compacted depth, divide the compacted volume by 0.86, the loose-to-compacted factor TM 3-34.62 gives for sand or gravel, to get the loose volume.
Related Calculators
Related Guides
From the Blog
Sources
NIST SP 811
Unit conversion reference (cubic feet, cubic yards, cubic metres).
NIST SP 811 — referenceTM 3-34.62/MCRP 3-40D.9, Earthmoving Operations (U.S. Army and Marine Corps, 2025)
Table 1-2 loose weights (gravel, sand) and Table 1-1 loose-to-compacted factor (0.86 for sand or gravel).
TM 3-34.62/MCRP 3-40D.9, Earthmoving Operations (U.S. Army and Marine Corps, 2025) — reference