Cubic Metres Aggregate To Tonnes Converter
Estimate aggregate tonnes from cubic metres, density, compaction, moisture, waste allowance, bulk bags, lorry loads and material cost.
Aggregate And Site Details
Tonnes To Order
Aggregate bulk density varies with source, grading, moisture, compaction and voids. Check supplier density for final ordering.
What This Aggregate Converter Does
Aggregates are often measured by volume on site but sold by weight. A driveway sub-base might be measured in cubic metres from length, width and compacted depth, while the supplier quotes in tonnes. This page converts cubic metres to tonnes by applying a material density, then adds an ordering allowance and shows bulk bags, lorry loads and cost.
The result is a planning estimate. Two aggregates with the same volume can have different weights because particle size, rock type, grading, moisture and compaction change bulk density. Wet sand can be much heavier than dry decorative gravel. MOT Type 1 after compaction is not the same as loose decorative stone tipped from a bag.
Formula
Base tonnes = cubic metres x bulk density in tonnes per cubic metreAdjusted tonnes = base tonnes x moisture or compaction factorOrder tonnes = adjusted tonnes x (1 + waste percentage)Bulk bags = order tonnes / bag tonnes, rounded upLorry loads = order tonnes / lorry tonnes, rounded upThe calculator rounds bags and lorry loads up because suppliers do not deliver a fraction of a bag. For loose tipped loads, a supplier may round to the nearest half tonne or minimum delivery quantity.
Typical Bulk Density Guide
| Material | Planning density | Notes |
|---|---|---|
| 10 mm gravel | 1.50 t/m3 | Decorative and drainage use varies by stone. |
| 20 mm gravel | 1.55 t/m3 | Common path and driveway estimate. |
| Ballast | 1.70 t/m3 | Mixed aggregate and sand for concrete batching. |
| MOT Type 1 compacted | 1.90 t/m3 | Compacted sub-base can be heavier than loose fill. |
| Sharp sand | 1.75 t/m3 | Moisture can shift weight noticeably. |
| Lightweight aggregate | 1.30 t/m3 | Check supplier data before ordering. |
Worked Examples
Gravel Path
2 m3 of 20 mm gravel at 1.55 t/m3 weighs 3.10 tonnes before allowance. With 10% extra, order about 3.41 tonnes.
MOT Sub-Base
3 m3 of compacted MOT Type 1 at 1.90 t/m3 is 5.70 tonnes before allowance. Sub-base projects often need careful depth and compaction checks.
Bulk Bags
If the order is 3.41 tonnes and each bulk bag is 0.85 tonnes, the rounded bag count is 5 bags.
How To Measure Cubic Metres First
For a rectangular area, multiply length by width by depth in metres. A path that is 10 m long, 1 m wide and 0.05 m deep is 0.5 m3. If the depth is in millimetres, divide by 1,000 before multiplying. For driveways, patios and sub-bases, measure several depths and use a sensible average if the excavation is uneven.
Compaction can change the amount needed. A loose material tipped onto site may settle or compact after laying. If the specification asks for a finished compacted depth, check whether the supplier or contractor allows for bulking and compaction.
Ordering Checks
- Ask the supplier whether the density is loose, compacted, dry or wet.
- Check the actual bulk bag weight printed on the product listing.
- Plan access for tipped delivery, pallets or crane-offload bags.
- Use a larger allowance for uneven ground, hand spreading and edges.
- Do not overload vehicles or trailers when collecting aggregate.
Loose Versus Compacted Volume
Loose volume is the space occupied by material before it is compacted or settled. Compacted volume is the finished space after rolling, vibrating, tamping or traffic. A sub-base may need more loose material than the finished compacted volume suggests. If a drawing states a compacted depth, ask the supplier or contractor what loose quantity is normally ordered for that specification.
Decorative gravel behaves differently from sub-base. A decorative layer may be placed loose and raked level, while MOT Type 1 is usually compacted in layers. Use the material setting that matches the finished use, then adjust the factor if your supplier gives a better number.
FAQs
How many tonnes are in one cubic metre of aggregate?
It depends on density. A common 20 mm gravel estimate is about 1.55 tonnes per cubic metre, while compacted MOT Type 1 can be nearer 1.90 tonnes per cubic metre.
Why does moisture matter?
Water adds weight and can fill voids, especially in sand and fine aggregate. Wet material may weigh more than the dry density estimate.
Should I round up bulk bags?
Yes. Bulk bags are sold as whole units. A small shortage can delay a job, so many projects use a waste allowance and round up.
Can I use this for concrete?
Use it only for aggregate weight estimates. Ready-mix concrete uses its own density and batching rules.
Is the density table exact?
No. It is a planning guide. Supplier density and product grading are better for final orders.
Sources
- British Standards Institution. (2013). BS EN 1097-3: Tests for mechanical and physical properties of aggregates. Determination of loose bulk density and voids. BSI. https://knowledge.bsigroup.com/
- Mineral Products Association. (2025). Aggregates: supply and use guidance. MPA. https://www.mineralproducts.org/
- National Highways. (2024). Specification for Highway Works, Series 800: Road pavements – unbound, cement and other hydraulically bound mixtures. National Highways. https://www.standardsforhighways.co.uk/
- National Institute of Standards and Technology. (2008). Guide for the Use of the International System of Units (SI), Special Publication 811. NIST. https://www.nist.gov/pml/special-publication-811