Gravel calculator

Volume, loose weight, and tonnage for a gravel base — in one calculation, by aggregate type. Cubic yards or cubic metres, tons or tonnes, with the waste factor done right and the tonnage stated as honestly as the material allows.

01 How the math works

Gravel is estimated in three steps: area, volume, then weight. For a rectangular base, area is length × width; for a circle it's π × radius². Multiply the area by the depth — with everything in consistent units — and you have volume. Weight is volume times the bulk density of the aggregate.

The density is where a gravel estimate splits from a concrete one. Crushed stone runs about 100 lb/ft³ (1,602 kg/m³), pea gravel about 95 lb/ft³ (1,522 kg/m³), and washed sand about 100 lb/ft³ (1,602 kg/m³). Pick the wrong one and the tonnage is off before you've measured anything.

For ordering, the raw volume gets a waste factor (typically 10%) and rounds up. Gravel is sold by the ton in some yards and by the cubic yard in others, and the two don't convert cleanly, because a yard's weight depends on what's in it. We show both so you can match whatever your supplier quotes.

02 Worked example

Take a gravel base under a backyard patio slab: a 10 ft × 12 ft slab with the base run 6 in past the slab on every side, so 11 ft × 13 ft of gravel at 4 in deep (3.35 m × 3.96 m × 100 mm).

Volume: 47.67 ft³ = 1.77 yd³ = 1.35 m³. At crushed-stone density of 100 lb/ft³, that's 4,767 lb = 2.38 tons (2,162 kg). With a 10% waste factor the order rounds up to 3 tons, or 2.0 yd³ if the yard sells by volume.

Swap the crushed stone for pea gravel at 95 lb/ft³ and the same base drops to 4,528 lb = 2.26 tons. Same hole, different ticket, because tonnage tracks density, not just volume.

03 When this calculator is wrong

The tonnage above is only as precise as the density, and density is the softest number in the whole calculation. Any gravel calculator that hands you a tonnage to two decimals is implying a precision the material doesn't have.

• Bulk density varies ±10% by source. The 100 lb/ft³ figure for crushed stone is an ASTM C29 typical value; the same size stone from a different quarry can run 90–110 lb/ft³ depending on the parent rock and how wet it is. On a 3-ton order that's a swing of roughly 0.3 tons — treat the tonnage as a band, not a point.
• The "2,700 lb per yard" shortcut over-orders light aggregate. Many calculators bake in a flat 2,700 lb/yd³ (crushed stone: 27 × 100). For pea gravel at 95 lb/ft³ the real figure is 2,565 lb/yd³ — the flat rule over-orders by about 5%.
• It computes loose volume, not compacted. A base course tamps down under a plate compactor, so the loose material you order is more than the finished compacted depth suggests. There's no single factor for this — it depends on the aggregate and the compaction effort — so confirm the allowance with your supplier rather than guessing.
• Wet gravel weighs more. The densities here are for dry, loose material. Aggregate delivered after rain carries water weight, which matters if you're paying by the ton and being handed a wet load.

04 What to do with the result

Order the rounded-up number, and order by whichever unit your supplier prices in. If the quote is by the ton, use the tonnage; if it's by the yard, use the cubic-yard figure. The two won't match a naive conversion, because the yard-to-ton rate is the density — the same number this calculator already applied.

One caution on rounding up: gravel is cheap and returns are impractical, so a modest over-order is the right call, but a bulk aggregate delivery is priced with a haul fee that a second trip repeats in full. Get the depth and the aggregate type right the first time, confirm the compaction allowance, and order once.

05 Common questions

How much area does a ton of gravel cover?

One US ton is 2,000 lb. At crushed-stone density of 100 lb/ft³ that's 20 ft³ of gravel, which spreads to about 60 ft² (5.57 m²) at a 4 in depth, or 120 ft² at 2 in. Halve the depth, double the coverage.

How many cubic yards are in a ton of gravel?

For crushed stone at 2,700 lb per cubic yard, one ton (2,000 lb) is about 0.74 yd³. Lighter aggregates like pea gravel give slightly more yardage per ton, because the same weight takes up more space.

How much does a yard of gravel weigh?

A cubic yard of typical crushed stone weighs about 2,700 lb (1,225 kg). Pea gravel is lighter at roughly 2,565 lb per yard. Use the weight, not the volume, when you're planning a haul or a trailer load.

How deep should a gravel base be?

For a patio or slab base, 4 in (100 mm) of compacted gravel is a common starting point, matching the worked example above. Driveways and soft or poorly draining soils want more. Base depth is a soil-and-load question, so confirm it against local practice or your supplier before ordering.

Is gravel sold by the ton or the yard?

Both — it depends on the yard. Weight-based pricing is common for bulk aggregate delivered by truck; volume pricing shows up at yards that sell by the loader bucket. This calculator gives you the order in both units so you can match the quote either way.