How Much Gravel Do I Need? (Simple Formula + Examples)
Updated 2026-07-01
"How much gravel do I need?" comes down to one thing: the volume of the space you're filling, converted into the weight suppliers sell by (tons). Here's the formula, a couple of worked examples, and a calculator that handles the conversion and waste for you.
Open the gravel calculator →How to figure out how much gravel you need
- Measure the area: Measure the length and width of the area in feet.
- Pick a depth: Choose a depth in inches — 2–3" for a top-up, 4" or more for a new driveway.
- Find the volume: Multiply length × width × (depth ÷ 12) to get cubic feet, then divide by 27 for cubic yards.
- Convert to tons: Multiply cubic yards by about 1.35 to get tons of gravel.
- Add waste: Add about 10% for spreading loss and compaction.
The formula
Gravel is priced by the ton, but you measure a space in feet. The bridge between them is volume and density.
Tons = (Length ft × Width ft × Depth ft) ÷ 27 × 1.35 × 1.10, where depth in feet is inches ÷ 12, ÷27 converts cubic feet to cubic yards, 1.35 is tons per cubic yard, and 1.10 adds 10% for waste.
Worked example: a driveway
Say your driveway is 40 ft long, 12 ft wide, and you want 4 inches of gravel.
Volume: 40 × 12 × (4 ÷ 12) = 160 cubic feet, or 160 ÷ 27 ≈ 5.9 cubic yards. Weight: 5.9 × 1.35 ≈ 8.0 tons, plus 10% waste ≈ 8.8 tons. Order about 9 tons.
How deep should the gravel be?
Depth is the number people most often get wrong. Rough guide:
- Topping up an existing driveway: 2–3 inches.
- New gravel driveway from bare ground: 4–6 inches total, built in layers.
- Paths and patios: 2–3 inches over a compacted base.
- Drainage / French drain: fill to the depth of the trench.
Don't forget waste and compaction
Gravel settles and spreads unevenly, and some is lost off the edges. Ordering exactly your calculated volume almost always leaves you short. Add roughly 10% — the calculator does this automatically.
Frequently asked questions
How many tons of gravel in a cubic yard?
About 1.35 US tons per cubic yard (≈2,700 lb) for typical dry crushed stone; by gradation and moisture it ranges roughly 1.2–1.5 tons.
How much area does a ton of gravel cover?
One ton of gravel is about 20 cubic feet. At 2 inches deep that covers roughly 120 square feet; at 3 inches deep, about 80 square feet.
Is it cheaper to buy gravel by the ton or by the bag?
Bulk by the ton is far cheaper for any real project. Bags only make sense for very small repairs where delivery isn't worth it.