Gravel Calculator (Australia)
A 6 m × 3 m area 75 mm deep needs about 1.35 m³ of gravel, which weighs about 2.3 tonnes.
Updated · Australian units: metres, millimetres, cubic metres · Built and checked by AI, which can make mistakes
Work out how much gravel you need
Result
This is an estimate. Real quantities depend on uneven ground, settling, compaction and the exact product, and bag sizes and weights vary by brand. Check the bag or ask your supplier before you buy.
Built and checked by AI. AI wrote this calculator and its explanations, researched the rates and ran the tests. AI can make mistakes, and the checks may not catch them all, so confirm anything important with an official source or a qualified professional. How we use AI.
Quick answer
A 6 m × 3 m area 75 mm deep needs about 1.35 m³ of gravel, which weighs about 2.3 tonnes.
Working in feet and inches? Use our US gravel calculator.
How to use the gravel calculator
- Choose the shape of the area: a rectangle, a circle, or enter the area if you already know it.
- Enter the measurements in metres and the depth in millimetres.
- Pick the bag size you plan to buy, and change the weight if your supplier quotes a different figure, and any extra for compaction.
- Optionally open “Compare costs” to see whether bags or bulk is cheaper.
- Press Calculate to see how much you need, with the steps.
How it’s calculated
Area = length × width (m²), or π × (diameter ÷ 2)² for a circle
Volume (m³) = area (m²) × depth (mm) ÷ 1,000
Litres = m³ × 1,000
Weight = volume × tonnes per m³
Bags = weight in kg ÷ bag weight, rounded up
Worked example
Gravel for a 6 m × 3 m area at 75 mm
- Area: 6 m × 3 m = 18 m².
- Volume: 18 m² × 75 mm ÷ 1,000 = 1.35 m³.
- In litres: 1.35 m³ × 1,000 = 1,350 L.
- Weight: 1.35 m³ × 1.68 tonnes per m³ = 2.27 tonnes.
- Bags: 2,268 kg ÷ 20 kg = 113.4, rounded up to 114 bags.
How much does gravel weigh?
Gravel is sold by volume (cubic metres) or by weight (tonnes), so it helps to know both. Dry gravel weighs about 1,680 kg per cubic metre, or about 1.68 tonnes per m³, according to Engineering ToolBox. Crushed stone, damp gravel and stone with a lot of fine material can be heavier, so ask your supplier for the weight of the exact product and change the figure in the calculator.
When you’d actually use a gravel calculator
- Laying a path or patio base. Get the volume and weight before you call a supplier.
- Checking a delivery quote. Suppliers quote by the tonne or cubic metre, so having both helps you compare.
- Planning how to move it. Know the weight before you load a ute or trailer.
What this calculator doesn’t include
- Irregular shapes. Split the area into rectangles and circles and add the results.
- A set compaction rate. Use the optional compaction field with the figure your supplier recommends.
- Delivery fees, minimum orders and local prices, which vary by supplier.
How we calculate
Area comes from your measurements. Volume is area × depth ÷ 1,000, in cubic metres. Weight uses 1.68 tonnes per cubic metre unless you enter your own figure, from Engineering ToolBox’s density for dry gravel. If you enter a compaction allowance, we add that percentage to the volume before working out the weight and bags. We calculate at full precision and round only for display. Bag counts are rounded up to whole bags.
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Frequently asked questions
How much does a cubic metre of gravel weigh?
Dry gravel weighs about 1.68 tonnes per cubic metre, according to Engineering ToolBox. Crushed rock and wet gravel can weigh more.
How many tonnes of gravel do I need?
Work out the volume from the length, width and depth, then multiply by the weight per cubic metre. A 6 × 3 m area 75 mm deep is 1.35 m³, or about 2.3 tonnes.
Should I order extra gravel?
Many people add a little extra for uneven ground and compaction. Ask your supplier how much to allow for the product and the job.