Gravel & Aggregate Calculator
Estimate the volume, weight and bags of gravel or aggregate you need.
Densities are approximate and vary by material and moisture. Order a little extra for settling and compaction.
Volume first, then weight
Aggregate is ordered by volume or weight, so the estimate starts with the space to fill: length times width times depth. Multiplying that volume by the material’s density gives the weight.
volume = length × width × depth · weight = volume × density
Because suppliers sell loose by the tonne or bulk bag and bagged by the sack, the calculator converts the weight into all three. Densities differ by material, so picking the right one matters as much as the measurements.
A 5 m by 3 m area at 5 cm deep is 0.75 m³. Filled with gravel (about 1.5 t/m³) that is roughly 1.13 tonnes — around 45 of the 25 kg bags, or about 2 bulk bags.
Ordering the right amount
Aggregate is heavy and awkward to top up, so a small over-order beats coming up short. Account for settling, especially on soft ground, and remember that decorative depths differ from structural sub-base depths.
Practical pointers
- Layer deep fills. Compact in stages rather than one thick layer.
- Density varies. Wet material weighs more; figures here are dry approximations.
- Bulk vs bags. Bulk bags are cheaper per tonne; sacks suit small jobs.