Road Base Calculator
Estimate road base, crusher run or crushed stone for a driveway, shed pad or paver bed. Includes a 20 percent compaction allowance, weight at an editable density, truck loads and an optional cost.
Leave blank for 1.
Extra material for settling. Blank counts as 0.
Spillage and uneven ground. Blank counts as 0.
Typical value. Ask your supplier. Blank hides the weight.
Blank hides the truck loads.
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Enter the dimensions to see the volume.
About the road base calculator
The Road Base Calculator estimates how much base material to order for a driveway, a shed floor, a patio or a paver walkway. Unlike a simple volume tool, it includes a compaction allowance, because loose road base is pressed down by a plate compactor or roller and ends up thinner than it was when delivered. If you ordered only the finished volume, you would run short.
Enter the shape and depth of the base, and the tool gives the order in cubic yards, cubic feet, cubic metres and litres, plus weight in US tons and tonnes, truck loads and an optional cost.
Why compaction changes the order
Road base is a graded mix of stone and fines. When it is dumped it contains air. Compacting squeezes that air out, so a 4 in layer of finished base needs more than 4 in of loose material. The allowance adds that extra. The default is 20 percent, which is a reasonable starting point, and typical values run from 15 to 25 percent depending on the material and the equipment. Your supplier or contractor can advise what is usual in your area.
Steps
- Choose the shape of the base: rectangle, circle, triangle, trapezoid or Known area.
- Enter the dimensions in whichever units you measured, and the depth of the finished, compacted layer.
- Check the Compaction field. It defaults to 20 percent. Lower it for a stone that compacts little, raise it for a fluffy mix.
- Add a Waste allowance if you want an extra margin. It defaults to zero.
- Review the density, truck capacity and optional price.
Formulas
Worked example: a 20 ft by 12 ft base
A base is 20 ft by 12 ft and 4 in deep. The net volume is 240 ft² times one third of a foot, which is 80 ft³ or 2.96 yd³. With the default 20 percent compaction the order grows to 3.56 yd³, which is 96 ft³ or 2.72 m³.
At the default density of 1.5 US tons per cubic yard the weight is 5.33 US tons, or 4.84 tonnes. A truck of 10 yd³ means one load. If you also add 10 percent waste, the order rises to about 3.91 yd³.
Worked example: a long driveway
A driveway is 50 ft long and 10 ft wide, with a finished base of 6 in. The net volume is 250 ft³, or 9.26 yd³. With 20 percent compaction the order is 11.11 yd³, and at 1.5 US tons per cubic yard that is about 16.67 US tons. With a 10 yd³ truck you need two loads.
Typical thickness and lifts
Typical figures, which vary by soil and use, are 4 to 6 in of base for a driveway and about 4 in under pavers. Place and compact the stone in lifts of 2 to 4 in rather than one thick layer, so each lift is dense all the way through. A 6 in base is normally two 3 in lifts. The depth you enter here is the finished, compacted thickness.
Density and units
The default density is 1.5 US tons per cubic yard, and it changes to 1.78 tonnes per cubic metre when you switch the unit. These are typical values for road base. Different quarries sell different mixes, so enter the number from your supplier if you have it.
For clean, uncompacted stone such as a drainage layer, the Gravel Calculator skips the compaction step. If you want to cover the base with a poured surface, use the Concrete Calculator.
Accuracy and limits
This is an estimate. Ground that is soft, uneven or being excavated to a changing depth will take more or less than a flat rectangle suggests. Compaction depends on moisture, equipment and the number of passes. Confirm quantities with your supplier and consider keeping a small reserve for finishing.
Privacy
Nothing is uploaded; every calculation runs in your browser and never leaves your device.
Related tools
The Area Calculator helps when the footprint is irregular. The Volume Converter converts between cubic yards and cubic metres, the Mass Converter switches between tons and tonnes, and the Percentage Calculator is handy for checking an allowance.
Frequently asked questions
How do I calculate how much road base I need?
Multiply the area by the finished depth, add the compaction allowance, then multiply by the density for weight. A 20 ft by 12 ft base that is 4 in deep needs 2.96 cubic yards net and 3.56 cubic yards with 20 percent compaction.
Why do I need to add a compaction allowance?
Loose road base is pressed down by a plate compactor or roller, so it ends up thinner than when delivered. The allowance adds the extra material you must buy to reach the finished thickness.
What compaction percentage should I use?
The default is 20 percent, and typical values run from 15 to 25 percent. Your supplier or contractor can suggest a figure for the material and equipment you are using.
How thick should a road base be?
Typical thicknesses are 4 to 6 inches for a driveway and about 4 inches under pavers. Compact in lifts of 2 to 4 inches rather than one thick layer.
How many tons of road base are in a cubic yard?
The default density is 1.5 US tons per cubic yard, or 1.78 tonnes per cubic metre if you switch units. These are typical values, so edit the density field to match your supplier.
Is the depth I enter loose or compacted?
Enter the finished, compacted thickness you want. The calculator applies the compaction allowance to work out how much loose material to order.