Check the path
Your calculation audit
Every total is shown as a short sequence so you can see what was measured, deducted, adjusted and rounded.
- 01Awaiting valid measurementsComplete the fields above to reveal the formula path.
Garden Materials & Beds
Gravel & topsoil calculator
Estimate loose-material volume, approximate weight and bag or bulk-bag quantities.
Transparent formulaFormula v1.0 · area × depth; weight uses an indicative material density
Scope boundary: Material density and bag volumes vary by supplier, moisture and product grade; confirm before ordering.
Measure clearly
Simple guidance
Measure the footprint and intended settled depth. Loose material volume changes with the finished depth, and approximate weight changes with product density and moisture.
Worked example
Follow the same logic
A 12 m² area at 50 mm deep needs 0.6 m³. At an indicative 1,600 kg/m³ gravel density that is approximately 960 kg.
Planning tipWrite down the product factor or pack size you used, so a later change is easy to trace.
Before you buy
Three quick checks
- 01
Use the planned finished depth, not a rough excavation depth.
- 02
Choose the bag or bulk-bag size a merchant actually sells.
- 03
Treat the weight as approximate because density varies.
Quick answers
Useful to know
Why is the weight only approximate?
Density changes with material type, grading and moisture. The volume is the core calculation; confirm the supplier’s quoted bulk density.
Should I use bags or a bulk bag?
Choose the purchase size available locally. The tool rounds up to whole bags or bulk bags so the list is easier to quote.
Review record
Transparent, source-ready method
Last reviewed: 15 October 2026. Formula version: v1.0. Source/review data to be added — Calculator.Shop does not present placeholder figures as an authoritative trade specification.