Road Base Calculator
Estimates road base volume and tonnes of crushed rock needed for a driveway.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the length, width and depth.
- Press Calculate.
How it works
Volume = length × width × depth; weight ≈ volume × 2 tonnes per m³ for compacted road base.
Worked example
10 × 3 × 0.1 m. = 3 m³ ≈ 6 tonnes.
Common mistakes
- Not compacting in layers — road base must be laid and compacted in lifts of about 100 mm.
- Ordering loose volume only; it compacts noticeably, so add around 20%.
Frequently asked questions
How much road base do I need?
Area × compacted depth gives volume; road base is roughly 1.8–2.2 tonnes per m³, and you should add for compaction.
How thick should road base be?
About 100 mm under paths and patios, and 150–200 mm under driveways, compacted in layers for a stable sub-base.
Why allow extra for compaction?
Road base compresses as it's rolled, so order extra loose volume (often ~20–30%) to reach the finished compacted depth.
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Cite this tool
Zerdly. (2026). Road Base Calculator. Retrieved from https://www.zerdly.com/tools/road-base-calculator/
Tip: Enter any known values to calculate the remaining results.
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