How to use the stone calculator
- Select the stone material. Each preset includes a typical bulk density and compaction allowance.
- Enter the area and the finished (compacted) depth.
- Override the compaction allowance if your spec or supplier gives a different figure, or choose “Custom” to enter your own density.
- Optionally enter the price per ton.
How the calculation works
Base materials such as crusher run contain fines that fill voids when compacted, so a layer compacted to 4 in needs noticeably more loose material than 4 in. Clean crushed stone (such as #57) has few fines and compacts much less. The calculator multiplies the finished volume by (1 + compaction allowance) to estimate the loose volume to order, then converts to tons with the material’s bulk density.
The preset densities and allowances are typical planning values, not product specifications. Quarries publish their own figures, which can differ by 10-15% or more.
Formula
- c
- Compaction allowance as a decimal
Worked example
30 × 12 ft pad, 4 in of crusher run base
Finished volume = 360 × (4 ÷ 12) = 120 ft³ = 4.44 yd³. With a 20% compaction allowance the loose volume is 5.33 yd³.
At 1.5 tons/yd³: 8.00 tons.
Assumptions and limitations
- Preset densities are typical figures; actual values depend on rock type, gradation and moisture.
- Compaction depends on equipment, moisture content and lift thickness.
- For structural bases (driveways, slabs, footings), follow the thickness and compaction specification for your project.
Frequently asked questions
How many tons of crushed stone do I need for a driveway?
Multiply length × width × depth (in feet) and divide by 27 for cubic yards, add the compaction allowance, then multiply by about 1.4-1.5 tons per yard. A 50 × 10 ft driveway with 4 in of base needs roughly 9-10 tons of crusher run.
Why does crusher run need a compaction allowance?
It is a mix of crushed stone and fines. When compacted, the fines fill the gaps and the layer gets thinner, so you start with more loose material.
Should I use the gravel or the stone calculator?
Use this calculator when you know the specific product. The gravel calculator is simpler, with one editable density.