Road base — also called aggregate base, crusher run, base rock or Class 2 base depending on the region — is the compacted layer that keeps driveways, parking pads and paver patios from rutting and sinking. Because it is ordered loose but measured compacted, simple volume math underestimates it. This calculator starts from the finished, compacted depth, adds the extra loose material that compaction squeezes out, and converts the total to tons and truckloads.
How to use the road base calculator
- Choose the area shape and enter its dimensions, or enter a known area.
- Enter the compacted depth — the thickness after the material has been rolled or plate-compacted.
- Keep or adjust the compaction allowance (20% by default).
- Check the density of the loose material; 1.5 tons per cubic yard is a typical starting point.
- Optionally enter your truck capacity and price per ton to see the number of loads and the material cost.
Road base formulas
Equivalently, you can multiply the compacted volume by the in-place (compacted) density. With the defaults, 1.5 tons per loose yard and 20% compaction work out to about 1.8 tons per compacted yard, or roughly 133 pounds per cubic foot.
Worked example: a gravel driveway base
A driveway 50 ft long and 12 ft wide needs 6 inches of compacted base: 600 ft² × 0.5 ft = 300 ft³ = 11.11 yd³ compacted.
Loose volume with 20% compaction: 300 × 1.20 = 360 ft³ = 13.33 yd³.
Weight: 13.33 × 1.5 = 20.0 tons. With a 14-ton tandem dump truck, that is 2 loads; at $25 per ton, the material costs about $500.
Ignoring compaction would have suggested only 16.7 tons — enough to leave the driveway an inch short across its whole length.
Why compaction matters
Loose aggregate contains a lot of air between the stones. Compacting forces smaller pieces into those gaps, increasing density and reducing thickness. A well-compacted base spreads vehicle loads across the soil beneath and resists frost heave and washouts. To get there, spread the material in lifts of 2 to 4 inches, dampen it so the fines bind, and compact each lift before adding the next. Placing the full depth at once leaves the bottom poorly compacted.
Typical compacted depths
| Use | Compacted base depth |
|---|---|
| Walkway or patio under pavers | 4 – 6 in |
| Shed or hot-tub pad | 4 – 6 in |
| Residential driveway (cars) | 6 – 8 in |
| RVs, delivery trucks, heavy equipment | 8 – 12 in |
| Soft clay or poorly drained soil | add depth and consider geotextile fabric |
The table under your result shows tons at other depths, which helps when comparing options. Many driveways finish with 2 to 3 inches of clean gravel on top; size that layer with the gravel calculator.
Ordering tips
Material names and specifications vary by state, so describe the job to your supplier and ask which product they recommend for a compacted base. Confirm whether prices are per ton or per yard, whether delivery is extra, and where the truck can safely dump. Have a plate compactor lined up before delivery day.
Frequently asked questions
How many tons of road base do I need for a driveway?
Find the compacted volume (length × width × depth in feet), add the compaction allowance, convert to cubic yards and multiply by the material density. A 50 × 12 ft driveway with 6 inches of compacted base needs about 13.3 loose cubic yards, or roughly 20 tons at 1.5 tons per yard.
What compaction factor should I use for road base?
Most crushed base loses about 15 to 25 percent of its loose volume when compacted, so a factor of 1.15 to 1.25 is common; 20 percent is a reasonable default. Well-graded material with more fines compacts more, and suppliers can often tell you the figure for their product.
How much does a cubic yard of road base weigh?
As delivered, loose road base usually weighs around 2,800 to 3,200 pounds per cubic yard (1.4 to 1.6 tons). After compaction the same material can reach roughly 3,500 to 3,900 pounds per cubic yard.
How deep should road base be?
Common compacted depths are about 4 inches for walkways and patios, 6 to 8 inches for residential driveways, and 8 to 12 inches for heavy vehicles or soft, clay soils. Local practice and soil conditions matter, so check with your supplier or an engineer for heavier loads.
Is road base the same as gravel?
No. Road base is crushed stone mixed with fine particles that lock together when compacted, making a firm, stable layer. Clean gravel has the fines washed out, so it drains better but stays loose. Driveways often use road base below and a layer of clean gravel on top.