Gravel is a primary material for decorative driveways and drainage. For 2026 UK standards, calculate tonnes by multiplying area by depth (typically 50mm) and applying a 10% compaction factor. Standard decorative gravel weighs 1.6 tonnes per m³. Ordering in bulk bags (850kg) is most cost-effective for domestic landscaping.
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Results
Volume Needed:0.00 m³
Weight Required:0.00 Tonnes (0 kg)
Delivery & Buying Options
Compare the most cost-effective ways to order your gravel:
Option A
25kg Handy Bags
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Individual Bags
Est: £0
Option B
Bulk Bags
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~850kg Bags (0.5m³)
Est: £0
Option C
Loose Tipper
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Total Tonnes
Est: £0
Estimated Labour:0.0 hrs
Expert Note: Results include your selected wastage allowance. Gravel settles over time; we recommend ordering 5-10% extra for future top-ups.
(Costs based on UK averages for standard decorative shingle/gravel)
Whether you're laying a new driveway, creating a garden path, or adding decorative borders, getting the right amount of gravel is crucial. Ordering too little halts your project, while ordering too much wastes money and leaves you with heavy bags to dispose of.
Our Gravel Calculator works out exactly how much material you need in cubic metres (m³) and converts it into metric tonnes and standard 850kg builders' bulk bags.
The Gravel Calculation Formula
To calculate gravel manually, you need to find the volume of your area in cubic metres. Measure the Length and Width of the area in metres, and the desired Depth in metres (e.g., 5cm = 0.05m).
Volume = Length (m) × Width (m) × Depth (m)
Once you have the volume, you need to multiply it by the material's bulk density (how heavy it is per cubic metre). Standard 20mm gravel typically weighs 1.6 tonnes per cubic metre.
Tonnage = Volume × 1.6
How Deep Should I Lay Gravel?
Driveways (50mm): For areas taking vehicle traffic, a depth of 50mm using 20mm angular gravel is recommended. This provides absolute coverage without causing tyres to sink.
Garden Paths (40mm - 50mm): For footpaths, 40mm is usually sufficient. Anything deeper makes pushing wheelbarrows or walking difficult.
Decorative Borders (30mm - 40mm): If it's purely for aesthetics over a weed membrane, a shallower depth of 30-40mm works perfectly.
Don't Forget Wastage Allowance (10% Rule)
When ordering aggregates, it is standard industry practice to order 5% to 10% extra material. This accounts for variations in ground levels, spillage during transport and laying, and natural settling over time. It is always cheaper to order slightly more upfront than to pay a second delivery charge for a single missing bag.
Frequently Asked Questions
How deep should decorative gravel be?
For standard 20mm decorative gravel on a path or driveway, a depth of 40mm to 50mm is ideal. Any deeper and it becomes difficult to walk or push a wheelie bin across.
Should I put a weed membrane under gravel?
Yes, laying a heavy-duty permeable woven landscape fabric (weed membrane) under the gravel is crucial. It stops weeds growing up from the soil and prevents your expensive gravel from sinking into the mud.
What size gravel is best for a driveway?
For driveways, 20mm angular gravel is best. It locks together under the weight of tyres. Smaller 10mm pea shingle will stick in tire treads and scatter everywhere.
How much does a bulk bag of gravel weigh?
A standard UK builders' bulk bag (Jumbo bag) of gravel typically weighs between 800kg and 850kg. Our calculator assumes 0.85 tonnes per bag for safety.
How much area does 1 tonne of gravel cover?
At a standard depth of 50mm (2 inches), 1 tonne of gravel will cover approximately 12 to 14 square metres.
Does the size of the gravel affect the tonnage?
Yes, smaller gravels (like 10mm shingle) tend to pack more tightly and have a higher density than larger, irregular stones (like 40mm slate), meaning you may need slightly more weight to cover the same volume.
How much does a bulk bag of gravel weigh?
A standard UK builders' bulk bag (Jumbo bag) of gravel typically weighs between 800kg and 850kg. Our calculator assumes 0.85 tonnes per bag for safety.
How much area does 1 tonne of gravel cover?
At a standard depth of 50mm (2 inches), 1 tonne of gravel will cover approximately 12 to 14 square metres.
Does the size of the gravel affect the tonnage?
Yes, smaller gravels (like 10mm shingle) tend to pack more tightly and have a higher density than larger, irregular stones (like 40mm slate), meaning you may need slightly more weight to cover the same volume.