Water Tank Capacity Calculator
Enter the internal length, width and height to calculate the storage volume (m³ / litres) and the full water weight (tonnes) for home, rooftop and basement tank sizing.
Input Data
Results
At a glance:Rectangular volume = length × width × height (m³). Volume (litres) = m³ × 1,000. Water density is about 1,000 kg/m³, so full water weight (tonnes) = volume (m³) × 1,000 ÷ 1,000 = volume (m³) — numerically equal, in tonnes. When sizing, also reserve installation space and check the structural load (tank plus water total weight).
Formula
Volume = length × width × height (m³)
Litres = volume × 1000
Full weight (t) = volume (m³)
$$V = L W H$$$$V_L = 1000 V$$$$M = V$$How to Use
- Enter the internal length, width and height of the tank (m).
- The tool outputs the volume (m³ and litres) and full water weight.
Case Studies
Rooftop tank
2×1×1 m.
Volume 2 m³, 2,000 L, full load 2 t.
Extension storage
1.5×1×0.8 m.
Volume 1.2 m³, 1,200 L, full load 1.2 t.
FAQ
Why does full weight equal the m³ number?
Water density is 1,000 kg/m³, so 1 m³ of water weighs 1,000 kg = 1 tonne — numerically equal.
How much load must the structure take?
Total tank-plus-water weight = water weight + tank self-weight; confirm the slab or supports can carry it when positioning.
Related Tools
References
Content review: Calculatorism Construction Team. Results are for reference only; please refer to the relevant authorities for the official figures.