Bulk material calculator
Volume and mass of gravel, sand or screenings for a base layer.
Fill in the fields and the result will appear here automatically.
Estimates a rectangular bulk-material layer, mass from your bulk density and a theoretical count of 25 kg bags. Bulk density includes voids between grains. Layer state and density must be consistent: a chosen allowance percentage does not itself convert loose volume to compacted volume.
How it works
Formula and logic
V = L·B·h/100 with L and B in m and h in cm. Required volume = V·(1+w/100); mass in tonnes = required volume·ρ with ρ in t/m³. 25 kg bags = ⌈mass·40⌉. Dimensions and density are positive and finite; w is 0–50%. Whole bags round upward using decimal input dimensions.
Example
A 5 × 4 m area with a 10 cm layer and 5% allowance needs 2.1 m³ of gravel — 3.36 tonnes. The example density is 1.6 t/m³.
Fields and units
- Area length — m
- Area width — m
- Layer thickness — cm
- Bulk density — t/m³
- Compaction allowance — %
How to use
- — Enter length, width and thickness in the displayed units.
- — Enter bulk density for the relevant material state and moisture.
- — Choose an allowance of 0–50%; the calculator does not determine compaction.
Method and limitations
- Calculation method
- Formula and logic
- Limitation
- Enter bulk density for the relevant material state and moisture. Choose an allowance of 0–50%; the calculator does not determine compaction.
FAQ
Which density should I enter?
Use bulk density for the relevant material condition, not individual-grain density. Obtain it from measurements or supplier data; there is no material selector.
What does the allowance do?
It multiplies geometric volume by 1+w/100. It does not establish settlement, moisture or the required allowance; you provide those conditions.
Does this calculate a concrete mix?
No. This is one material with a chosen density. The concrete calculator also computes geometric pour volumes, not mix grade or composition.
What does the bag count mean?
It is mass including allowance divided by 25 kg, rounded up. Actual packaging, delivery and price are unknown, so no cheaper purchasing method is inferred.