Gravel Driveway Calculator
To figure gravel for a driveway, multiply length × width × depth in feet for each layer and divide by 27 for cubic yards, then multiply by about 1.85 for tons of compacted crusher run. For example, a 12 × 50 ft driveway with a 4-inch base and a 3-inch surface needs 12.96 cubic yards, about 24 tons.
How to figure gravel for a driveway
- Measure the driveway. Measure the length and width in feet, and add the area of any turnaround or parking pad.
- Choose each layer's depth. Decide how deep the base and the surface layer will be once compacted, and divide each depth in inches by 12.
- Find each layer's cubic yards. Multiply the area by each layer's depth in feet, then divide by 27.
- Convert to tons. Multiply by 1.85 for compacted crusher run, 1.43–1.48 if it's spread loose, or 1.35–1.50 for clean stone such as #57.
- Work out what to order. Crusher run is delivered loose, so order 1.25–1.30 loose cubic yards for each compacted yard.
- Add the layers and round up. Add the layers together and round up to the next half ton or half cubic yard.
| Layer | Compacted | Tons | Order (loose) |
|---|---|---|---|
| Base, 4 in | 7.41 yd³ | 13.7 | 9.29–9.62 yd³ |
| Surface, 3 in | 5.56 yd³ | 10.28 | 6.97–7.21 yd³ |
| Total | 12.96 yd³ | 23.98 | 16.26–16.83 yd³ |
How deep should a gravel driveway be?
There's no single right depth: it depends on the soil and the traffic. The Federal Highway Administration's guide to building gravel roads calls for a surface layer at least 3 inches deep, over a base thick enough to carry the expected loads. Place gravel in separate layers once the total passes 4 inches, so each layer compacts properly, and make each layer at least twice as thick as its largest stone. Over geotextile fabric, the guide recommends at least 6 inches in the first layer.
For heavily used driveways that connect to a gravel road, Iowa's statewide design manual says an 8-inch compacted base of Class A crushed stone may be needed. The calculator starts with a 4-inch base and a 3-inch surface; change either to suit your driveway.
What size gravel to use for each layer
Use crushed stone that still has its fines. The FHWA guide says good surface gravel needs the right blend of stone, sand and fines: the stone should be fractured, and the fines bind the gravel into a crust that sheds water. Broken, angular stone also resists movement under loads better than rounded stone.
Washington State DOT's crushed surfacing, for example, is 1¼-inch minus for the base course and ¾-inch minus for the top course. The FHWA's sample surface-gravel specification tops out at ¾ or 1 inch, with 3–12% fines in wetter climates and 8–15% in drier ones. Clean stone such as #57 drains well but has no fines to bind it; the crushed stone calculator lists the common sizes.
Gravel for common driveway sizes
Tons of compacted crusher run for common driveway sizes, by total depth. Use the calculator for your own layers.
| Driveway | 3 in | 4 in | 6 in | 8 in |
|---|---|---|---|---|
| 10 × 50 ft | 8.6 t | 11.4 t | 17.1 t | 22.8 t |
| 12 × 50 ft | 10.3 t | 13.7 t | 20.6 t | 27.4 t |
| 12 × 100 ft | 20.6 t | 27.4 t | 41.1 t | 54.8 t |
| 16 × 50 ft | 13.7 t | 18.3 t | 27.4 t | 36.5 t |
| 20 × 50 ft | 17.1 t | 22.8 t | 34.3 t | 45.7 t |
| 24 × 50 ft | 20.6 t | 27.4 t | 41.1 t | 54.8 t |
Crown the driveway so it drains
The FHWA guide recommends finishing gravel with a crown of about 4%, which is ½ inch of drop per foot on each side. On a 12 ft driveway crowned in the middle, each edge sits 3 inches below the center.
How far a ton of driveway gravel goes
A ton of compacted crusher run is only about 0.54 cubic yards, because compacting packs more stone into each yard.
| Depth | 1 ton, compacted | 1 ton, loose | 20 tons, compacted |
|---|---|---|---|
| 2 in | 88 sq ft | 110–114 sq ft | 1,751 sq ft |
| 3 in | 58 sq ft | 73–76 sq ft | 1,168 sq ft |
| 4 in | 44 sq ft | 55–57 sq ft | 876 sq ft |
| 6 in | 29 sq ft | 37–38 sq ft | 584 sq ft |
Other calculators
For one material at one depth, use the gravel calculator. For stone sizes such as #57 and ¾-inch minus, see the crushed stone calculator.
Frequently asked questions
How do you figure gravel for a driveway?
Measure the length and width in feet, multiply by each layer's depth in feet (inches ÷ 12) and divide by 27 for cubic yards. Then multiply by about 1.85 for tons of compacted crusher run, and add the layers. A 12 × 50 ft driveway with a 4-inch base and a 3-inch surface is 12.96 cubic yards, about 24 tons.
How deep should gravel be for a driveway?
No single depth fits every driveway. The Federal Highway Administration's gravel-road guide calls for at least 3 inches of surface gravel over a base thick enough for the traffic, placed in separate layers once it's more than 4 inches deep. Iowa's design manual says heavily used driveways off gravel roads may need an 8-inch compacted crushed stone base.
How much does 1 ton of driveway gravel cover?
A ton of compacted crusher run (about 0.54 cubic yards) covers about 58 sq ft 3 inches deep or 44 sq ft 4 inches deep. Spread loose, a ton covers 73–76 sq ft 3 inches deep.
How much driveway will 20 tons of gravel cover?
20 tons of compacted crusher run is about 10.81 cubic yards: roughly 1,168 sq ft 3 inches deep or 876 sq ft 4 inches deep. That's a 12 ft wide driveway about 97 ft or 73 ft long.
What is a good size rock for a driveway?
Angular crushed stone that still has its fines, so it binds into a hard surface. Washington State DOT's crushed surfacing is 1¼-inch minus for the base course and ¾-inch minus for the top course, and the Federal Highway Administration's gravel-road guide says each layer should be at least twice as thick as its largest stone.
Related calculators
Sources and methodology
Volumes use (length × width × depth) ÷ 27 with all measurements in feet, for each layer. Compacted crusher run uses Washington State DOT's compacted weight for crushed surfacing (1.85 tons per cubic yard); the calculator weighs the compacted volume, then converts it to the loose cubic yards you order using WSDOT's loose weight (1.43–1.48). Loose crusher run and clean stone use their loose weights, which is why some results show a range. Depth and construction guidance is from the FHWA's Gravel Roads Construction & Maintenance Guide and Iowa's SUDAS design manual; stone sizes are WSDOT's gradings. Order amounts are rounded up to the next half cubic yard or half ton. Tons are US short tons (2,000 lb).
- WSDOT Design Manual M 22-01.23, Exhibit 620-1 (September 2024)
- WSDOT Standard Specifications for Road, Bridge, and Municipal Construction M 41-10 (2027), Division 9: Section 9-03.9(3) (crushed surfacing)
- FHWA and South Dakota LTAP: Gravel Roads Construction & Maintenance Guide (August 2015)
- Iowa SUDAS Design Manual, Chapter 5 (Roadway Design), Section 5I-4: Driveway Design Criteria (2013 revision)
- FHWA Federal Lands Highway, Earthwork Design (PDDM supplement), Exhibit 5.1 A (January 2026)
- Penn State Center for Dirt and Gravel Road Studies: DGLVR Materials Calculator
- NIST Special Publication 811 (Guide for the Use of the SI), Appendix B.8: conversion factors