BuildCalcs Gravel Calculator
Estimate how much gravel, shingle or aggregate you need for a rectangular area.
How the gravel calculation works
Length × width × depth gives the volume in cubic metres. The calculator then applies the chosen bulk density and waste allowance to estimate tonnes.
Choosing a depth
The required depth depends on the intended use and aggregate size. Decorative gravel, paths, drainage layers and driveways can require very different build-ups.
Frequently asked questions
Why are tonnes only approximate?
The same volume can weigh differently depending on aggregate type, grading, voids and moisture content.
Can I use this for MOT Type 1?
Yes for a volume-to-weight estimate, but enter an appropriate density and remember compacted thickness may differ from loose-delivered thickness.
Related calculators
Estimating gravel by volume and weight
Gravel requirements depend on both area and compacted depth. The calculator first converts the entered depth from millimetres to metres, multiplies it by the area to obtain cubic metres, and then uses the selected bulk density to estimate tonnes. Because aggregates vary, the density should be treated as a planning figure rather than an exact product specification.
Depth has a large effect on quantity
Doubling the depth doubles the calculated volume. That makes an accurate depth assumption more important than small differences in length or width. Decorative gravel laid over a prepared base may need a relatively shallow layer, while driveways and load-bearing construction require a properly designed sub-base and specification that this calculator does not provide.
Ordering bulk bags or loose aggregate
Supplier bulk bags are commonly sold by nominal weight, but actual product weight, moisture and bag size can vary. Compare the calculated tonnes with the supplier's stated bag weight or loose-load minimum. On irregular areas, split the space into simple rectangles and triangles, estimate each part, then add a modest allowance for levelling and local low spots.