Aggregate calculator
Work out how much crushed stone or road base to order for a compacted sub-base, accounting for how much loose material settles once compacted.
Aggregate calculator
Work out how much crushed stone or road base to order for a compacted sub-base, accounting for how much loose material settles once compacted.
Enter length, width and compacted depth to estimate the aggregate you need.
Aggregate to order
Project summary
How it works
Estimate only. Compaction allowance and density both vary by material gradation and how well the base is compacted; use supplier figures if you have them and confirm the order before delivery.
Aggregate calculator
The depth you want is compacted, the material you buy is loose
Aggregate is delivered loose and settles once it is spread and compacted, so the compacted depth you plan for is smaller than the loose depth you actually place. This calculator scales the compacted volume up by a compaction allowance to get the order quantity, rather than reporting the compacted volume itself as what to buy.
Compaction allowance and density both depend on the material
Both figures used here, the compaction allowance and the density, are working assumptions rather than fixed constants. They vary by material gradation, whether it is crushed stone, road base or a specific blend, and by how well the base is compacted. Use supplier figures instead of the defaults if you have them, especially for a load-bearing base like a driveway or shed pad.
Frequently asked questions
Why is the order volume larger than the compacted volume?
Loose aggregate has more air space between particles than compacted aggregate. Compacting it packs the particles tighter and reduces the volume, so ordering only the compacted volume leaves the base short once it is rolled or plate-compacted.
What compaction allowance should I use?
This calculator applies a default compaction allowance as a starting point, but the real figure depends on the material gradation and compaction method. Check with your supplier for a material-specific figure before finalizing a large order.
How much aggregate do I need for a driveway base?
For a 60 by 10 foot driveway with a 6 inch compacted base, you need about 11.1 cubic yards or roughly 16.7 tons of aggregate, before adding a waste and compaction allowance. The calculator scales the compacted volume up to account for the loose-to-compacted ratio, so the order quantity reflects what you actually need to buy.
What is the difference between loose and compacted aggregate?
Loose aggregate has more air space between particles than compacted aggregate. When you spread and compact it, the volume decreases, so ordering only the compacted volume leaves the base short. This calculator scales the compacted volume up by a compaction allowance to get the order quantity, rather than reporting the compacted volume itself.
How much aggregate do I need for a shed pad?
For an 8 by 10 foot shed pad with a 4 inch compacted base, you need about 1 cubic yard or roughly 1.5 tons of aggregate, before allowance. The calculator works this out from your dimensions and compacted depth, and shows both the compacted volume and the loose order volume so you can see the difference.
What type of aggregate is used for a sub base?
A dense graded crushed stone or road base material, such as crusher run, is the standard choice for a sub base because it compacts into a firm, stable layer. Clean washed stone that does not compact is the wrong choice here, even though it may be cheaper per ton. The calculator's material list includes the common base materials.
How do I know how much to compact?
The calculator applies a default compaction allowance as a starting point, but the real figure depends on the material gradation and the compaction equipment. Check with your supplier for a material-specific figure before finalizing a large order. The compaction field is editable so you can use whatever number your project requires.
Why does the order volume show as larger than what I calculated?
Because loose aggregate occupies more space than the same material after it has been compacted. The calculator shows both the compacted volume and the order volume, and the order volume is larger because you need to buy enough loose material to reach the specified depth once it has been compacted.