Volume Calculator Australia
Convert between litres, cubic metres, gallons (imperial & US), millilitres, cubic feet, cubic inches, and fluid ounces instantly. Perfect for water tanks, concrete, fuel, shipping containers, and everyday measurements.
Volume Conversions in Australia
Australia uses the metric system for volume measurement — litres (L), millilitres (mL), and cubic metres (m³) are the official units under the National Measurement Act. But many industries still refer to imperial gallons on legacy equipment, and US gallons appear on imported American products, fuel economy comparisons, and some chemical or industrial inputs.
Getting the conversion right matters. A mistake between imperial and US gallons on a fuel order means a 20% error. Misreading cubic metres and litres on a concrete slab order can cost thousands. This calculator converts between all common units so you don't have to memorise conversion factors.
Worked Example: Water Tank Sizing
You're installing a rainwater tank on a 200 m² house in Sydney with 1 metre of roof catchment width. Annual rainfall is approximately 1,200 mm. How much water can you collect?
- Catchment area: 200 m² of roof
- Annual rainfall: 1.2 m
- Annual collection: 200 × 1.2 = 240 m³
- 240 m³ × 1,000 = 240,000 L per year
- If you want a tank that holds 3 months' supply (60,000 L): 60 m³
- 60 m³ ÷ 1,000 = 60,000 L or approximately 13,200 imperial gallons
Use the volume calculator above to convert between m³, litres and gallons for your specific tank dimensions.
Worked Example: Concrete for a Slab
A concrete slab measuring 6 m × 4 m × 0.15 m (100 mm thick):
- Volume in m³: 6 × 4 × 0.15 = 3.6 m³
- Litres: 3.6 × 1,000 = 3,600 L
- At $320/m³ for standard 32 MPa concrete, cost ≈ $1,152
Concrete is ordered in cubic metres in Australia. Our Concrete Calculator can help with bags and mix ratios too.
Common Volume Conversions
| From | To | Multiply By |
|---|---|---|
| 1 Litre | Millilitres | 1,000 |
| 1 Cubic Metre | Litres | 1,000 |
| 1 Imperial Gallon | Litres | 4.54609 |
| 1 US Gallon | Litres | 3.78541 |
| 1 Cubic Foot | Litres | 28.3168 |
| 1 US Fluid Ounce | Millilitres | 29.5735 |
Frequently Asked Questions
There are 1,000 litres in 1 cubic metre (m³). So a cube 1 m × 1 m × 1 m holds exactly 1,000 L of water. This is the standard conversion used in concrete mixing, water tank sizing, and swimming pool calculations in Australia.
An imperial gallon (UK/Australia) is 4.54609 litres. A US gallon is 3.78541 litres. So an imperial gallon is about 20% larger than a US gallon. Australia historically used imperial gallons but now officially uses litres.
Measure length, width and height in metres, then multiply: L × W × H = volume in m³. Multiply by 1,000 to get litres. For example, a 2m × 1m × 0.5m tank = 1 m³ = 1,000 L.
A '10,000 litre' water tank holds 10,000 litres, which equals 10 m³ or approximately 2,200 imperial gallons. These tanks are popular on Australian rural properties for rainwater harvesting.
Divide millilitres by 1,000 to get litres. For example: 750 mL ÷ 1,000 = 0.75 L. To go the other way, multiply litres by 1,000: 1.5 L × 1,000 = 1,500 mL.
Disclaimer: Volume conversions are based on standard international definitions. Imperial gallon uses the UK/Australian standard (4.54609 L). US customary units differ.