Formula
Base volume = length × width × (depth millimetres ÷ 1,000). Order volume = base volume × (1 + allowance percent ÷ 100). Estimated tonnes = order volume × bulk density in tonnes per cubic metre.
Trade & Construction
Gravel Calculator
Estimate gravel volume and approximate weight from area, depth, waste allowance and bulk density.
Calculator
Working calculator
Live result0.99 m³ · 1.58 t0.90 m³ measured volume + 10.0% allowance at 1.60 t/m³
Formula used
Base volume = length × width × (depth millimetres ÷ 1,000). Order volume = base volume × (1 + allowance percent ÷ 100). Estimated tonnes = order volume × bulk density in tonnes per cubic metre.
This is the method behind the answer, so the result can be checked rather than simply trusted.What-if check
Allowance and tonne sensitivity
Same measured rectangle and depth, with common ordering allowances. Use this table to discuss bags, scoops, tonnes or truck increments with the supplier.
| Allowance | Order volume | Estimated weight |
|---|---|---|
| 0.0% | 0.90 m³ | 1.44 t |
| 5.0% | 0.95 m³ | 1.51 t |
| 10.0% | 0.99 m³ | 1.58 t |
| 15.0% | 1.03 m³ | 1.66 t |
Visual proof
Area × depth
The orange layer shows why millimetres must be converted to metres before volume is calculated.
Printable calculation report
Result: 0.99 m³ · 1.58 t. Assumption: The area is treated as a rectangle. Irregular areas should be split into rectangles and added together.
- Length
- 6
- Width
- 3
- Depth
- 50
- Allowance
- 10
- Bulk density
- 1.6
- Page/date context
- 2026-05-16 UTC page version
- Page URL
- https://calculationtime.com/calculators/gravel-calculator
Worked example
For a 6 m by 3 m area at 50 mm depth: depth = 50 ÷ 1,000 = 0.05 m. Base volume = 6 × 3 × 0.05 = 0.90 m³. Add 10% allowance: 0.90 × 1.10 = 0.99 m³. At 1.60 t/m³, estimated weight = 0.99 × 1.60 = 1.58 tonnes.
Professional note
Master’s Tip: ask the supplier what bulk density and minimum delivery increment they use before ordering. Decorative gravel, road base and drainage stone can need different depth, compaction and tonne-per-cubic-metre assumptions.
Regional and unit assumptions
Defaults use metres, millimetres, cubic metres and metric tonnes. The arithmetic is general rectangular volume; supplier density, compaction, bag size and delivery rounding must be checked locally.
Assumptions and limitations
- The area is treated as a rectangle. Irregular areas should be split into rectangles and added together.
- Depth is entered as the finished target depth in millimetres and converted to metres before volume is calculated.
- Bulk density is a planning input only. Actual tonnes per cubic metre vary by aggregate type, grading, moisture, voids and compaction.
- This calculator estimates quantity for ordering and quote notes. It does not specify drainage design, sub-base preparation or structural engineering requirements.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Base volume = length × width × (depth millimetres ÷ 1,000). Order volume = base volume × (1 + allowance percent ÷ 100). Estimated tonnes = order volume × bulk density in tonnes per cubic metre.
Standard or basis
Defaults use metres, millimetres, cubic metres and metric tonnes. The arithmetic is general rectangular volume; supplier density, compaction, bag size and delivery rounding must be checked locally.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: ask the supplier what bulk density and minimum delivery increment they use before ordering. Decorative gravel, road base and drainage stone can need different depth, compaction and tonne-per-cubic-metre assumptions.
Related calculators
Questions
How do I calculate how much gravel I need?
Multiply length by width by depth in metres to get cubic metres, then add an allowance for uneven ground, edges and ordering tolerance.
Why does the calculator ask for bulk density?
Gravel is usually ordered by volume, weight or bag count. Bulk density converts cubic metres into an estimated tonne figure, but the supplier value can vary by material and moisture.
What depth should I use for gravel?
Use the finished target depth for your job. Decorative paths, driveways, drainage layers and sub-base materials can need different depths, so follow the project specification or supplier guidance.
Does this include compaction?
Only if you enter a depth and density that already reflect the compacted material you intend to order. Compaction changes volume and density, so record the assumption in the printable report.
Should I round up the result?
Yes for real orders. Suppliers may sell by bag, scoop, tonne or truck increment, so round after checking the supplier’s delivery and minimum-order rules.
Calculation note
Gravel estimating is simple volume arithmetic, but the practical result depends on material behaviour. The same rectangular area can produce different tonne estimates when the stone size, moisture, void spaces or compaction change.
Volume comes before weight
The core calculation is geometric: length times width times depth. Keeping cubic metres visible first makes the estimate easier to check on a drawing, quote or classroom worksheet before any supplier density is applied.
Bulk density is the uncertain part
Aggregate weight is not fixed by volume alone. Particle size, grading, stone type, moisture, air voids and compaction all affect how many tonnes fit into a cubic metre. That is why this page makes density an editable input instead of hiding one universal number.
Allowances should be recorded, not hidden
Edges, uneven subgrade, spreading loss and ordering increments often mean the bought quantity is higher than the measured geometric volume. Recording the allowance in the printable report helps a homeowner, landscaper or supplier understand why the order was rounded.
Sources and further readingCaterpillar: Earthwork volumes reference tablesNIST: SI Units — Length