Excavation Volume Calculator
Calculate rectangular excavation volume.
What this tool calculates
Calculate rectangular excavation volume. The main inputs on this page are Length (m), Width (m), Depth (m). The result is intended to be readable immediately, with the explanation below available when you need to verify the method.
Method and calculation basis
To add VAT, gross = net × (1 + rate). To extract VAT from a VAT-inclusive amount, net = gross ÷ (1 + rate) and VAT = gross − net. Simply subtracting the VAT percentage from a gross price is not the reverse calculation.
Worked examples
Add 20% VAT
£100 net becomes £120 gross.
Extract 20% VAT
£120 gross ÷ 1.20 = £100 net, so VAT is £20.
Understanding the result
The output should be read in the units shown beside the result. If you are comparing alternatives, keep all unchanged assumptions identical and alter one input at a time. That makes it easier to see which value is responsible for the difference.
Assumptions, edge cases and accuracy
This is a quantity or geometry estimate, not structural design approval. Product yield, compaction, joints, substrate condition, reinforcement, waste and site tolerances can materially change the amount required.
Sources and methodology
- BSI / applicable British Standards — Relevant construction measurement and design standards where applicable
- Manufacturer technical data — Product coverage, yield, density and installation requirements
Method reviewed for Instant Solvers V10.0 · October 2026. If you find a calculation or explanation that needs correcting, use the site Contact page and include the tool URL and the values you entered.