Gravel Calculator
Work out how much gravel you need for a driveway, path, or garden bed. Enter the area and depth to get the volume in cubic metres and the weight in tonnes.
🪨 What is a Gravel Calculator?
A gravel calculator works out how much gravel you need to fill an area to a given depth, in both volume and weight. It multiplies the length, width, and depth to find the volume in cubic metres, then multiplies by the bulk density of the material to find the weight in tonnes. Because gravel is sold both by the cubic metre and by the tonne, having both figures lets you order the right amount and compare supplier prices fairly.
These calculations come up in landscaping and construction all the time. Laying a gravel driveway, filling a French drain, topping a garden path, bedding a patio, or backfilling around pipework all start with the same question: how much material to buy. Ordering too little means a second delivery with its own minimum charge, while ordering too much wastes money and leaves a pile to shift. A quick calculation based on the actual dimensions avoids both problems.
A common misconception is that gravel weighs the same as solid rock. It does not: loose gravel includes air gaps between the stones, so its bulk density of around 1.5 tonnes per cubic metre is well below that of solid stone. Another mistake is ignoring depth units, since depth is usually measured in centimetres while length and width are in metres. This calculator handles the conversion so the volume comes out correctly in cubic metres.
Enter the length and width of the area, the depth of gravel, and the material, and the calculator returns the area, the volume in cubic metres, and the weight in tonnes and kilograms. Bulk density presets are provided for gravel, pea gravel, sand, crushed stone, and topsoil, with a custom option for any density you know.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — A Small Gravel Bed
A 5 m by 4 m area at 10 cm deep, loose gravel
Example 2 — A Crushed Stone Path
A 10 m by 3 m path at 5 cm deep, crushed stone
Example 3 — A Gravel Driveway
A 12 m by 3 m driveway at 8 cm deep, loose gravel
❓ Frequently Asked Questions
🔗 Related Calculators
How do you calculate how much gravel you need?
Multiply the area by the depth to get the volume, then multiply by the bulk density to get the weight. For a 5 m by 4 m area at 10 cm deep, the volume is 5 × 4 × 0.1 = 2 cubic metres. At a gravel density of 1.5 tonnes per cubic metre, that is 2 × 1.5 = 3 tonnes.
How much does a cubic metre of gravel weigh?
Loose gravel weighs about 1.5 tonnes per cubic metre, though the figure ranges from roughly 1.4 to 1.7 tonnes depending on the stone type, size, and moisture. Pea gravel is nearer 1.4 tonnes, while sand and crushed stone are closer to 1.6 tonnes per cubic metre. This calculator lets you pick the material or enter your own density.
How deep should gravel be?
For a garden path or decorative bed, 5 cm of gravel is usually enough over a suitable sub-base. For a driveway that carries cars, aim for 10 to 15 cm, often in two layers over a compacted base. Deeper gravel resists rutting but needs more material, which this calculator will quantify for you.
How many tonnes of gravel are in a cubic metre?
About 1.5 tonnes of gravel make up one cubic metre, based on a typical bulk density of 1.5 tonnes per cubic metre. So if a supplier quotes by the tonne and you have worked out your volume in cubic metres, multiply the cubic metres by roughly 1.5 to estimate the tonnes you need to order.
How do you convert gravel volume to weight?
Multiply the volume in cubic metres by the bulk density in tonnes per cubic metre. For 2 cubic metres of gravel at 1.5 tonnes per cubic metre, the weight is 2 × 1.5 = 3 tonnes, or 3,000 kg. Different materials have different densities, so choose the right one for an accurate weight.
What is the bulk density of gravel?
Bulk density is the mass of loose material per unit of volume, including the air gaps between the stones. For gravel it is typically 1.4 to 1.6 tonnes per cubic metre. It is lower than the density of solid rock because of the voids. This calculator uses 1.5 tonnes per cubic metre for gravel by default, with presets for other materials.
How much gravel do I need for a driveway?
Measure the length and width of the driveway and choose a depth of 10 to 15 cm. For a 12 m by 3 m driveway at 8 cm deep, the volume is 12 × 3 × 0.08 = 2.88 cubic metres, which at 1.5 tonnes per cubic metre is about 4.3 tonnes. Add around 10% for compaction and settling.
Should I order extra gravel?
Yes. Add about 10% to your calculated amount to allow for compaction, for gravel working into the sub-base, and for uneven ground. Running slightly over is far cheaper and easier than ordering a second small delivery, which often carries a minimum charge and an extra delivery fee.
Can this calculator handle sand or topsoil?
Yes. The material dropdown includes gravel, pea gravel, sand, crushed stone, and topsoil, each with a representative bulk density, plus a custom option for any density you know. The volume calculation is the same for all of them; only the density used to convert volume to weight changes.
How do I convert my measurements if they are in feet?
Convert feet to metres by multiplying by 0.3048, and inches to centimetres by multiplying by 2.54. This calculator works in metres for length and width and centimetres for depth, so convert imperial measurements first. A 40 by 10 foot area is about 12.2 by 3.05 metres.