Aggregate Calculator

Aggregate for concrete, drainage and bases: tonnes or tons and m³ or cubic yards, with 25 kg bags and 850 kg bulk bags counted for you.

Aggregate is the general name for crushed stone, gravel and sand used in building: 20 mm or 10 mm gravel for concrete and drainage, sub-base for paths and driveways, and decorative chippings. In the UK it's sold in 25 kg bags and 850 kg bulk bags, or loose by the tonne. Enter the area and depth and this calculator gives the volume in m³ or cubic yards, the weight in tonnes or tons, and the number of bags or bulk bags. One 850 kg bulk bag of 20 mm gravel is about 0.53 m³, enough for about 10.6 m² at 50 mm deep.

Units

Bag sizes

Material

Area

Shape

Length

Width

Depth

Density (tonnes per m³)

t/m³

Extra for waste and compaction

Bag size

Volume: 0.63 m³
Weight: 1.01 tonnes
Bags: 41

Bags needed by size
25 kg bag	41
850 kg bulk bag	2
20 kg bag	51
0.5 ft³ bag	45

Price (optional)

Price is per

How it was worked out

Area: 4 m × 3 m = 12 m²; × 50 mm (0.05 m) deep = 0.6 m³
Plus 5% extra = 0.63 m³
0.63 m³ × 1.6 t/m³ = 1.01 tonnes (1,008 kg)
1,008 kg ÷ 25 kg per bag = 40.32, rounded up to 41 bags

Typical weights of common materials

Material	t/m³	tons/yd³	lb/ft³
Concrete	2.40	2.02	150
Gravel	1.60	1.35	100
Pea gravel	1.60	1.35	100
Crushed stone / crushed rock	1.60	1.35	100
River rock	1.50	1.26	94
Landscape rock / pebbles	1.50	1.26	94
Crushed limestone	1.60	1.35	100
Decomposed granite	1.50	1.26	94
Crusher run	1.60	1.35	100
Road base	1.70	1.43	106
Crusher dust	1.50	1.26	94
Aggregate (20 mm)	1.60	1.35	100
All-in ballast	1.65	1.39	103
MOT Type 1 sub-base	1.80	1.52	112
Sand	1.60	1.35	100
Topsoil	1.30	1.10	81
Garden soil	1.30	1.10	81
Fill dirt	1.40	1.18	87
Mulch	0.35	0.29	22
Bark chippings	0.30	0.25	19
Asphalt (compacted)	2.32	1.96	145

Loose, as-delivered figures; asphalt and concrete are as laid. Moisture, stone size and source change the real weight, so use your supplier's figure when you have it. Tons are US short tons (2,000 lb).

Common use cases

20 mm gravel for drainage around a house or a soakaway
Aggregate for mixing concrete (use the cement calculator for the mix)
Chippings for paths and borders
A drainage layer behind a retaining wall

How to use

Choose feet and inches or metres and millimetres, and the country whose bag sizes you want.
Enter the length and width of the area, or switch the shape to a circle, triangle or a known area. Use Add another area for L-shapes and separate beds.
Enter the depth of aggregate. Decorative layers are often 40 to 50 mm deep; drainage and base layers 100 mm or more.
Check the density and the extra allowance. Change the density if your supplier quotes a different figure.
Read the volume, weight and bag count, and add a price per ton, cubic yard, m³ or bag for a cost estimate.

FAQ

How many bulk bags of aggregate do I need?

Work out the tonnes, then divide by 0.85 for 850 kg bulk bags. One tonne is about 1.2 bulk bags. The calculator rounds up to whole bags for you.

How much aggregate makes a cubic metre of concrete?

For a 1:2:4 mix, about 0.88 m³ of gravel (roughly 1.3 tonnes) and 0.44 m³ of sand per cubic metre of concrete. The cement calculator works out the whole mix.

What weight should I use for aggregate?

Typical loose gravel and crushed stone is around 1.6 tonnes per m³; finer or wetter material can be heavier. Change the density if your supplier gives a figure.

Common use cases

How to use

FAQ

How many bulk bags of aggregate do I need?

How much aggregate makes a cubic metre of concrete?

What weight should I use for aggregate?

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