Cubic Metres Ballast To Tonnes Converter
Convert ballast volume into tonnes for concrete batching, shed bases, footings and small building work, with moisture, waste, bulk bag and price checks.
Ballast Inputs
Ballast Result
Ballast density changes with grading, moisture and compaction. Check supplier bag weights or weighbridge tickets for final ordering.
What This Ballast Converter Does
Ballast is a mixed aggregate, usually sand and gravel, commonly used for concrete. It is often measured by cubic metre on site but sold by tonne or by bulk bag. This converter changes cubic metres into tonnes, then adds practical order information such as rounded bulk bag count and material cost.
The calculator is useful for small slabs, shed bases, garden walls, footings, kerb haunching and general concrete preparation. It does not design a concrete mix. If the job has a specified concrete strength, exposure class or structural purpose, follow the specification or use ready-mixed concrete from a supplier.
Formula And Method
Base tonnes = cubic metres x density. Adjusted tonnes = base tonnes x moisture factor. Order tonnes = adjusted tonnes x waste allowance. Bulk bags = order tonnes divided by bag weight, rounded up.
The default density of 1.70 t/m3 is a planning value for typical loose ballast. Wet ballast may weigh more, and very open or dry material may weigh less. The moisture factor lets you alter the estimate without changing the selected density.
Density And Ordering Guide
| Ballast condition | Planning density | Use note |
|---|---|---|
| Light loose ballast | 1.65 t/m3 | Useful where supplier product is dry or open graded. |
| Typical ballast | 1.70 t/m3 | Good first estimate for many domestic jobs. |
| Damp ballast | 1.80 t/m3 | Moisture adds weight and can alter handling. |
| Supplier bulk bag | label weight | Use the actual bag listing for ordering. |
Worked Examples
Two Cubic Metres
2 m3 of typical ballast at 1.70 t/m3 is 3.40 tonnes before allowance. With 8% extra, the order is about 3.67 tonnes.
Bulk Bag Order
If a bulk bag is 0.85 tonnes, a 3.67 tonne order rounds to five bags. That may leave a little spare for low spots and barrowing loss.
Damp Delivery
Two cubic metres at a damp density of 1.80 t/m3 gives 3.60 tonnes before waste, showing why wet material can change delivery weight.
Measuring Ballast Volume
For a rectangular slab or base, multiply length by width by depth in metres. If the depth is in millimetres, divide by 1,000 first. For trenches and footings, use the average width and depth after excavation. If the bottom is uneven, take several measurements and use a realistic average rather than the shallowest point.
Remember that ballast is usually only one part of concrete. Cement, water and mixing method all affect the final result. A ballast tonnage estimate helps with buying aggregate, but it does not confirm the correct cement ratio for a load-bearing job.
Buying And Handling Notes
- Bulk bags are often sold by approximate weight, not exact volume.
- Wet ballast can be heavier and harder to shovel.
- Keep bags on firm ground so they can be lifted safely.
- Check access for a delivery lorry and crane-offload.
- Do not rely on ballast volume to judge finished concrete yield without a mix calculation.
Concrete Batching Boundary
Ballast quantity is only one part of concrete planning. A common small-job recipe may describe cement and ballast by volume, but a structural specification may call for ready-mixed concrete or designed proportions. If a drawing states a concrete strength, exposure class or reinforcement detail, do not treat a ballast order as a full concrete design.
Water also matters. Wet ballast already contains moisture, while very dry ballast can pull water from the mix. The right water content depends on workability and strength, not only on how easy the mix is to shovel. Use this page to buy ballast, then use the correct mix instructions for the job.
Vehicle Payload Check
Collecting ballast yourself can be risky if the weight is underestimated. A single cubic metre can be around 1.7 tonnes before allowance, which is beyond many cars, trailers and small vans. Check vehicle payload, axle limits and loading method before collecting loose material or multiple bags. If in doubt, choose delivery rather than overloading a vehicle.
FAQs
How many tonnes are in one cubic metre of ballast?
A typical planning value is about 1.70 tonnes per cubic metre, but moisture and grading can change it.
How many bulk bags do I need?
Divide the order tonnes by the bag weight and round up. The calculator does this automatically.
Is ballast the same as concrete?
No. Ballast is aggregate used in concrete. Concrete also needs cement, water and correct mixing.
Should I add waste?
Yes for many small jobs. Barrowing, spillage and uneven excavations can use more material than the exact volume.
Can I use this for structural concrete?
Use it only for aggregate quantity. Structural work needs a specified concrete mix and proper site controls.
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 and concrete materials guidance. MPA. https://www.mineralproducts.org/
- British Standards Institution. (2023). BS 8500: Concrete. Complementary British Standard to BS EN 206. BSI. https://knowledge.bsigroup.com/
- 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