A gravel driveway 50 ft long and 12 ft wide, built with 6 in of #3 stone, 3 in of #57 and 3 in of crusher run, needs about 37 tons of stone with 10% extra: 17.1 tons of #3, 8.6 tons of #57 and 11.3 tons of crusher run. That is roughly 30.6 cubic yards off the truck, because loose stone shrinks by about a fifth when it is compacted.
How the gravel driveway calculator works
Each layer is worked out on its own, because each stone weighs something different and is often priced differently:
tons = length × width × compacted depth ÷ 27 × tons per cu yd × (1 + extra %)
loose cu yd to order = compacted cu yd × compaction factor × (1 + extra %)
The densities are WSDOT's unit weights for stone compacted on the roadway (Design Manual Exhibit 620-1): 1.85 tons per cubic yard for dense-graded crushed stone such as crusher run, dense grade aggregate (DGA) and #411, and 1.40 tons per cubic yard for open-graded clean stone, which covers #3 and #57. The default compaction factor of 1.25 comes from the same table: crushed base weighs 2,950 lb per cubic yard as delivered and 3,700 lb once compacted, and 3,700 ÷ 2,950 = 1.25. Clean stone settles less than that, so the factor errs on the side of an extra yard.
Worked example: 50 × 12 ft, three layers
| Layer | Compacted volume | Tons with 10% | Loose cu yd with 10% |
|---|---|---|---|
| #3 base, 6 in | 11.11 cu yd | 17.1 | 15.3 |
| #57 middle, 3 in | 5.56 cu yd | 8.6 | 7.6 |
| Crusher run top, 3 in | 5.56 cu yd | 11.3 | 7.6 |
| Total, 12 in | 22.22 cu yd | 37.0 | 30.6 |
By hand for the base: 50 × 12 × 0.5 = 300 cu ft, ÷ 27 = 11.11 cu yd, × 1.40 = 15.56 tons, × 1.1 = 17.1 tons.
Which stone goes in which layer
Fixr's guide describes the usual build as three layers, ideally 4 in each for 12 in in all, with 3 in enough for some materials: a base of #3 (1 to 2 in clean stone) or item #4, a middle of #57 (about ¾ to 1 in), and a top of your choice. For the top, crusher run (stone plus stone dust), dense grade or #411 (#57 blended with stone dust) pack into a hard, drivable surface; clean or rounded stone on top rolls under tires and migrates. Keep the finish layer dense and the lower layers open so water drains down and out.
Gravel driveway cost
The cost block prices each layer by the ton from Fixr's 2022 guide: #3 base at $15 to $30 a ton, #57 at $65 to $75, crusher run at $25 to $35, #411 at $20 to $40 and dense grade at $30 to $40 (priced as crushed limestone), plus $50 to $100 delivery. Labor for grading, compacting and spreading is $2.00 to $2.17 per sq ft, taken from Fixr's two-car example where $1,150 to $1,250 of a $1,750 job was labor on 576 sq ft. For the example driveway that comes to about $2,650 installed, $2,350 to $2,950 at the US average, or about $1,400 for stone and delivery if you spread it yourself. Choose your state to scale the figures. As a check, Fixr's finished-driveway range of $1.74 to $5.21 per sq ft gives about $1,050 to $3,150 for the same 600 sq ft. Fixr notes that some suppliers will not deliver less than 10 cubic yards.
Geotextile fabric and edging
On soft or wet soil, a woven geotextile under the stone keeps clay from pumping up into the base. FHWA's gravel roads guide recommends at least 6 in of stone in the first layer on the fabric, never driving equipment directly on it, overlapping strips by at least 18 in, and a Class 2 fabric under AASHTO M288 for most driveways. The calculator lays strips along the drive and adds a strip whenever the width exceeds the roll: a 12 ft drive on a 12 ½ ft roll is one strip, 625 sq ft. Edging is counted along both sides, 100 ft for this drive; check the length of the pieces your store sells.
Crown and drainage
Shape the top with a crown so water leaves the surface: FHWA recommends about ½ in per foot, roughly 4%, from the center to each edge. On a 12 ft drive the center sits 3 in above the edges. Potholes almost always start where water stands.
Next questions
- Comparing gravel to asphalt or concrete on the same footprint? Use the driveway calculator, or the asphalt calculator for hot mix alone.
- Steep lot? Stone washes out on steep grades; check yours with the driveway slope calculator.
- Volume of any other pile or pit: the cubic yard calculator.
More paving tools are on the driveways and paving hub.