Estimate gravel for a bed, path, or driveway

The job

You're ordering gravel for a path or bed and the supplier sells by the bag or the tonne. Get the volume wrong and you're either shoveling leftovers or making a second run.

Measure, then add margin

Enter length × width (or just the area directly), the depth in millimeters, and pick a material — the density is preset for gravel, crushed stone, sand, and topsoil, or set your own. Add a waste/compaction percentage; 10% is a typical allowance since delivered material settles.

• Result reads in cubic metres, tonnes, and bag count for your chosen bag weight — plus ft³ and lb equivalents.
• Depth matters more than people expect: doubling depth doubles the tonnage, and 50 mm paths need compacted base anyway.

Worked example

A 6 m × 1.2 m garden path at 40 mm deep with standard gravel: 0.288 m³ ≈ 0.46 tonnes — plus 10% waste, about 0.51 t, or twenty 25-kg bags. Order 21.

Where it stops

Flat rectangular areas — split L-shapes into rectangles and sum them. Densities are averages; wet sand and loose topsoil vary ±15%, so the waste margin isn't optional. Coverage for round areas: use area = πr² and enter it as the area value.