Gravel Calculator - Work Out How Much Aggregate You Need (UK)
Work out how much gravel or decorative aggregate you need by area and depth, in bulk bags, cubic metres and tonnes.
Interested? Then → Quotato for Landscapers · More advice on the Blog & Chips guides.
How to use this calculator
Measure the area you want gravelled in square metres and decide a depth in millimetres - around 50mm is typical for a decorative finish. We work out the volume, weight in tonnes and how many bulk bags to order.
How we calculate this
- Volume (m³) = area × (depth ÷ 1000).
- Weight (tonnes) = volume × 1.6 (a typical gravel density of 1.6 t/m³).
- Bulk bags = volume ÷ 0.5, rounded up, as a bulk bag holds roughly 0.5 m³ (about 800kg).
Worked example
For a 10 m² area at 50mm deep: volume = 10 × 0.05 = 0.5 m³. That's 0.5 × 1.6 = 0.8 tonnes, which is one bulk bag. Going deeper or wider soon tips you into a second bag.
UK notes & gotchas
- Around 50mm is a typical decorative depth - enough to cover the ground without being a slog to walk on.
- A ~0.5 m³ bulk bag of gravel is roughly 800kg, so make sure your access can take the delivery.
- Lay a weed-control membrane beneath the gravel and consider edging to stop it migrating.
FAQ
How deep should I lay gravel?
Around 50mm for a decorative finish. For a driveway you'd want a deeper, well-compacted sub-base beneath the decorative layer.
How much does a bulk bag of gravel weigh?
Roughly 0.5 m³, about 800kg for typical gravel. We base bag counts on volume as it's more reliable.
How many tonnes do I need?
Volume in m³ × 1.6. For 10 m² at 50mm that's about 0.8 tonnes.
Do I need a membrane under gravel?
Yes - it keeps weeds down and stops the stones sinking into the soil over time.
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