Gravel calculator
Loose aggregate is bought by weight and spread by volume, so the bulk density is the number that matters.
%
Material needed
2.898tonnes
- Loose volume to order
- 1.725
- Compacted volume
- 1.500
- Bags at your bag size
- 116
- Bulk bags, about 850 kg each
- 4
- In cubic yards
- 2.256
- Area covered
- 30.00
Show the working
- Length = 10
- Width = 3
- Depth = 50
- Material = 1680
- Bag size = 25
- Compaction allowance = 15
- Area covered = 10 * 3 = 30
- Compacted volume = 30 * 50 / 1000 = 1.5
- Loose volume to order = 1.5 * (1 + 15/100) = 1.725
- weight = 1.725 * 1680 = 2898
- Material needed = 2898 / 1000 = 2.898
- Bags at your bag size = ceil(2898 / 25) = 116
- Bulk bags, about 850 kg each = ceil(2898 / 850) = 4
- In cubic yards = 1.725 / 0.764554857984 = 2.256 21
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- volume = area x depth
- weight = loose volume x bulk density
Bulk densities are for dry material as delivered. Wet aggregate can be 20% heavier, and you pay for the water.
A compacted sub-base settles by 10 to 20%, which is why the loose volume is larger than the finished layer.