AsphaltCalc

Stone calculator

Aggregate Cubic Meter Calculator

Full metric workflow. Enter metres and millimetres, get cubic metres, tonnes and bulk bag counts.

Stockpiles of crushed limestone and dense-graded base with a loader bucket and plate compactor on a prepared driveway base, sized by a crushed stone calculator
Dense-graded base is ordered loose and paid for loose, then loses roughly a fifth of its depth under the compactor — order the compacted depth plus that shrinkage.

Your project

m
m
mm

Crews typically order 5-10% extra to cover compaction, spillage and uneven subgrade.

Aggregate needed

4.2

cubic metres

Tonnes
6.72
Kilograms
6,720
US tons
7.41
Cubic yards
5.49
Bulk bags (850 kg)
8

UK bulk bags hold roughly 850 kg (0.5-0.6 m³) of aggregate, not a full tonne, despite often being called tonne bags.

The shareable link reopens this calculator with your exact inputs.

Metric aggregate densities

Aggregate is quoted in kg/m³ or tonnes/m³ outside North America. Loose crushed stone and gravel run about 1,600 kg/m³ (1.6 t/m³), compacted MOT Type 1 sub-base about 2,100 kg/m³, sharp sand 1,500 and topsoil 1,400.

Solid rock is much denser than the loose aggregate made from it: granite is 2,650 kg/m³ solid, but crushed and loose it is only around 1,600 because roughly 40% of the volume is air.

Depth in millimetres

Typical metric depths: 50 mm for decorative gravel, 100 mm sub-base under a patio, 150 mm under a driveway, 200-250 mm under heavy traffic. Divide millimetres by 1,000 to get metres before multiplying.

Stone weight conversion diagram of kilograms to pounds to stone and of cubic yards to tons using material density
Two different conversions share the word stone: the imperial mass unit (14 lb) and bulk material, where cubic yards only become tons once you apply density.

Tonnes per cubic metre

Materialkg/m³Tonnes/m³
Crushed stone / gravel (loose)1,6001.60
MOT Type 1 (compacted)2,1002.10
Sharp sand1,5001.50
Topsoil1,4001.40
Solid granite2,6502.65

Frequently asked questions

+How many tonnes in a cubic metre of gravel?

About 1.6 tonnes for loose crushed stone or gravel, and up to 2.1 tonnes for compacted MOT Type 1 sub-base.

+How many bulk bags in a cubic metre?

Roughly two. A standard bulk bag holds 0.5-0.6 m³, which is about 850 kg of aggregate.

+How do I convert cubic metres to cubic yards?

Multiply by 1.308. One cubic metre is 1.31 cubic yards; one cubic yard is 0.765 cubic metres.

+What depth of sub-base does a driveway need?

150 mm of compacted MOT Type 1 for cars, 200-250 mm where vans or delivery lorries use it, over a well-drained, compacted formation.