Blog /
Gravel Calculator: How Much Gravel Do I Need?
The Formula
Length (ft) x Width (ft) x Depth (inches) / 324 = Cubic Yards
Suppliers sell gravel two ways: by the cubic yard and by the ton. You need both numbers because the price sheet might list one and the delivery ticket lists the other.
Cubic Yards to Tons
Gravel weighs roughly 1.3 to 1.6 tons per cubic yard depending on the stone, its gradation, and how wet it is. Typical figures (Trussly uses the first three):
- Crushed stone and #57: about 1.4 tons/yd
- Pea gravel: about 1.4 tons/yd
- River rock: about 1.5 tons/yd
- Crusher run (3/4” minus, with fines): about 1.5 tons/yd
Your supplier’s conversion is the one that counts. Ask for it.
Wet gravel is heavier. If you’re buying by the ton after a rain, part of what you’re paying for is water.
Driveway Example
A single-lane driveway: 12 feet wide, 60 feet long, 4 inches deep.
12 x 60 x 4 / 324 = 8.89 cubic yards
At 1.5 tons per yard for crusher run: 13.3 tons.
But that’s the installed depth. You need to account for compaction.
The Compaction Factor
Loose gravel loses volume when you compact it. A common rule of thumb is to order about 20% more than the compacted depth: a 4-inch finished depth takes about 4.8 inches of loose stone.
For our driveway: 12 x 60 x 4.8 / 324 = 10.67 cubic yards. At 1.5 tons/yd: 16 tons.
That’s 2.7 more tons than the uncompacted number. Order short and you’re paying for a second delivery.
Not all applications need compaction. Decorative gravel in a garden bed sits loose. Driveway base, French drain backfill, and paver sub-base all get compacted. If a compactor touches it, add the 20%.
Depth by Application
Different jobs call for different depths.
Driveway base (crusher run): 4-6 inches compacted. Six is better if your soil is clay. Clay holds water, water softens the base, and your gravel sinks into the mud. Ask anyone with a gravel driveway on red clay how many times they’ve had to add stone.
Paver sub-base: compacted dense-graded base, then about 1 inch of bedding sand. ICPI guidance runs about 4 to 6 inches of base for patios and walks and 8 inches or more where cars drive, deeper on poor soil.
Retaining wall backfill: 3/4” clean stone behind the block face, 12 inches wide minimum, from base to within 6 inches of the top. A 40-foot, 3-foot wall needs about 5 tons of drainage gravel just for the backfill zone.
French drain backfill: Fill the trench with 3/4” clean stone (no fines) around the perforated pipe. The stone should extend from 2 inches below the pipe to 2 inches above it at minimum, though most contractors fill within 6-8 inches of grade.
Walkway or garden path: 2-3 inches of pea gravel or decomposed granite over landscape fabric. No compaction needed. These settle on their own. If the path borders garden beds, the mulch calculator uses the same cubic-yard formula for the beds alongside it.
Footing base: A 4-6 inch compacted gravel pad under concrete footings is standard practice. The footing calculator gives you concrete volume; this one gives you the gravel underneath.
Shed foundation pad: 4 inches of compacted crusher run, leveled. For a 10 x 12 shed: 10 x 12 x 4.8 / 324 = 1.78 yards. Two yards.
Driveways: The Real Math
Gravel driveways should be built in layers. The standard cross-section:
Bottom: 4 inches of large stone (2-4” rock) for stability on soft subgrade. Middle: 4 inches of #57 stone (3/4” clean). Top: 2 inches of crusher run (3/4” minus with fines) that compacts into a hard surface.
That’s 10 inches total loose depth across three lifts. For a 12 x 60 driveway:
12 x 60 x 10 / 324 = 22.2 cubic yards total across all three layers.
At about 1.4 tons per yard, that’s around 31 tons of stone. A lot of people pour 4 inches of crusher run directly on native soil and call it done. It works for a year or two, then the gravel migrates into soft spots and you’re adding more stone.
The Delivery Question
Truck sizes vary by supplier and state weight limits. A tandem dump usually carries somewhere around 10 to 15 tons; a tri-axle carries more. Ask what fits in one load, and what delivery costs below their minimum order.
If you have a pickup truck and the quarry is close, you can haul it yourself. But a cubic yard of gravel weighs 2,800 pounds, and a half-ton truck’s payload maxes at 1,500-2,000 pounds. You’d need 10+ trips for a driveway. Pay the delivery fee.
Common Mistakes
Using the wrong stone for the job. Pea gravel on a driveway looks nice for a week, then displaces under tires and rolls into the yard. River rock in a French drain clogs with sediment because the rounded stones don’t lock together. Crusher run on a garden path tracks into the house on shoes.
Not accounting for edge spillage. Gravel without borders (edging, timber, or stone) spreads outward over time. Without edging, a gravel driveway spreads and thins in the middle. Install edging or plan on adding stone.
Running the Numbers
Trussly has calculators for gravel and mulch (cubic yards and tons) and topsoil (with a compaction allowance). Enter the dimensions and depth and it gives you yards, tons, and bag counts. The budget calculator runs the math backward if you’re working from a dollar amount instead of a measurement.