Base and top course for a drive
Driveway Gravel Calculator
480 sq ft of drive with a 6 in base as spread with no top course entered needs 8.89 cu yd of stone, about 13.1 tons. Set each layer’s depth and weight below.
Your estimate
8.89 cu yd to order
6.67 cu yd once compacted, over 480 sq ft.
- Tons to orderEach layer’s loose cubic yards × its weight13.11 tons
- Base course6 in as spread8.89 cu yd, 13.11 tons
- Top courseNone entered0 cu yd, 0 tons
- Base tons across printed weights1.47 to 2.16 tons per cu yd, from the producers13.1–19.2 tons
- Volume once compactedPenn State’s share of 0.75 after compacting6.67 cu yd
Tons use the weights in the boxes. WSDOT’s figures are dry; a load weighed on a scale decides the bill.
How to calculate a driveway’s gravel
- Measure the drive and multiply length by width. A 40 × 12 ft drive is 480 sq ft.
- Multiply the area by the base depth in inches and divide by 12: 480 × 6 ÷ 12 = 240 cu ft.
- Divide by 27 for cubic yards, then multiply by the weight per cubic yard: 8.89 cu yd × 1.475 = 13.11 tons.
- A top course is the same sum with its own depth and weight. The example has none, so its line stays at zero until you enter a depth.
- A layer measured after compacting is divided by 0.75 first, so 6 in finished is 8 in loose.
Each layer is the same sum with its own depth and weight. The loose volume is what you order; the tons follow from the loose volume and the weight the supplier uses for loose stone. WSDOT Design Manual, Exhibit 620-1 (Sep 2024)
- Loose layer, Penn State driving surface aggregate
- 6–8 inPenn State Driving Surface Aggregate Handbook (2025)
- Once compacted
- 4.5–6 inPenn State Driving Surface Aggregate Handbook (2025)
- Share kept after compacting
- 0.75 of the loose depthPenn State Driving Surface Aggregate Handbook (2025)
- Crushed surfacing base, truck measure
- 1.475 tons per cu ydWSDOT Design Manual, Exhibit 620-1 (Sep 2024)
- Crushed surfacing top course, truck measure
- 1.425 tons per cu ydWSDOT Design Manual, Exhibit 620-1 (Sep 2024)
The base and the top course
Our data gives one loose depth for a driving layer of crushed stone, 6–8 in, and it gives no separate depth for a top course. The base box therefore starts at the low end of that range, and the top course box starts at 0 in. Enter the depths your builder or the local code specifies for each course. Penn State Driving Surface Aggregate Handbook (2025)
The two layers carry their own weight boxes because WSDOT weighs its base and its top course differently. Each weight is per loose cubic yard, the figure a truck carries, so the tons match the stone that is ordered.
Loose depth and finished depth
Stone packs down under a roller and under traffic. Penn State’s handbook takes 8 in loose to 6 in finished, and 6 in to 4.5 in, so the share kept is 0.75 in both cases.
Choose “After compacting” to type the depth the finished driveway should reach. The form then orders the loose stone that makes it, and shows the compacted volume beside the order.
Where sources disagree
Weight of a cubic yard of crushed stone base
- 1.475 tons, WSDOT truck measure (loose in the truck)WSDOT Design Manual, Exhibit 620-1 (Sep 2024)
- 1.47 tons, Martin Marietta base, crushed concreteMartin Marietta aggregates calculator
- 1.78 tons, Martin Marietta base, sand and gravelMartin Marietta aggregates calculator
- 1.95 tons, Martin Marietta base, graniteMartin Marietta aggregates calculator
- 2.15 tons, Martin Marietta base, traprockMartin Marietta aggregates calculator
- 1.76 tons, Vulcan crusher run, sand and gravelVulcan Materials aggregate tonnage estimator
- 1.86 tons, Vulcan crusher run, sandstoneVulcan Materials aggregate tonnage estimator
- 1.96 tons, Vulcan crusher run, graniteVulcan Materials aggregate tonnage estimator
- 2.16 tons, Vulcan crusher run, traprockVulcan Materials aggregate tonnage estimator
The form uses WSDOT’s truck weight, because the depth is loose and stone arrives by the truckload. The producers’ figures run from 1.47 to 2.16 tons, each for their own rock type, and none is tied to a product your yard sells. Type the weight on your supplier’s ticket.
How much a layer shrinks when it is compacted
- 0.75 of the loose depth: 8 in to 6 in, 6 in to 4.5 in (Penn State)Penn State Driving Surface Aggregate Handbook (2025)
- 0.77: 2,850 lb per cu yd loose, 3,700 lb compacted (WSDOT top course)WSDOT Design Manual, Exhibit 620-1 (Sep 2024)
The depth change uses Penn State’s 0.75, and the tons use WSDOT’s loose weight. WSDOT’s pair implies 0.77, which would give a loose order about 3% smaller for a finished depth. The form keeps the larger order, the safer side to buy.
How deep a driveway base should be
- 6–8 in loose, for an unpaved low-volume road (Penn State, not a residential driveway spec)Penn State Driving Surface Aggregate Handbook (2025)
- 2–4 in drainage base under walks and slabsSakrete All Purpose Gravel data sheet
Penn State gives the only loose-layer depth for a vehicle surface in the bulk-materials data, and it covers unpaved roads, not a residential drive. The form starts at its low end, 6 in. The walk and slab figure is for a different job and does not set a driveway’s depth.
Before you order a driveway’s stone
Order the base first and the top course second, so the base can be checked for grade and firmness before the top course covers it. Add your own spare for the edges and any soft spots found on the subgrade.
Driveway gravel questions
How much gravel does a 12 × 40 ft driveway need?
A 12 × 40 ft drive is 480 sq ft. A 6 in base laid loose is 240 cu ft, or 8.89 cu yd, about 13.11 tons at WSDOT’s 1.475 tons per cu yd. A top course is a second layer over the base, entered on its own line.
Why is the loose depth bigger than the finished depth?
Stone packs down under a roller and traffic. Penn State’s handbook takes 8 in loose to 6 in finished, and 6 in to 4.5 in, a share of 0.75 both times. When the depths are finished, the form divides them by that share to find the loose stone to order.
What is the top course on a gravel driveway?
It is the upper layer of crushed stone, laid over the base. The form weighs it at WSDOT’s crushed surfacing top course, 1.425 tons per cu yd loose. Its depth is zero until you enter one, so a drive with only a base shows no top-course stone.
Why do tons for the same drive differ between suppliers?
Producers weigh the same kind of rock differently. The Martin Marietta figures for crushed base run from 1.47 to 2.15 tons per cu yd, and the Vulcan crusher run from 1.76 to 2.16. Ask the yard which weight its scale and its ticket use.
Is the gravel weight a wet or a dry weight?
WSDOT’s table gives unit dry weights, the stone with no water in it. Wet stone weighs more, so a scale ticket can read above the table figure on a rainy day.
Does the calculator add stone for waste?
No. It gives the volume of each layer at the depths you enter. Add your own allowance for the edges, low spots and a soft subgrade, since the form does not guess at those.
What if the driveway is not a rectangle?
Split it into rectangles, work out each area in square feet and add them. Type the total in the area box, which the form takes in place of length and width. The cubic yards to tons calculator turns a yard figure into tons for any other stone.
A planning aid, not an engineering calculation: your local code and building inspector have the final word. Terms