Aquarium Calculator
Find a tank's capacity in litres and US gallons, and what it will weigh when filled, before it goes on the stand.
Your results
Worked example
A common starter tank, 60 cm long, 30 cm wide, 36 cm tall:
- Volume: 60 × 30 × 36 = 64,800 cm³, and 1,000 cm³ is 1 litre, so 64.8 L
- US gallons: 64.8 ÷ 3.785 = 17.1 gal
- Water weight: water is 1 kg per litre, so 64.8 kg
- Filled weight: adding a 10 percent allowance for glass, substrate, and decor: 64.8 × 1.10 = 71.3 kg, roughly the weight of an adult person, on four small feet
How this calculator works
The filled weight adds a flat 10 percent allowance for the glass, substrate, filter, and decor. Real tanks also hold a bit less than the outside dimensions suggest, because of glass thickness and the gap left at the top, typically about 5 to 10 percent less water than the headline number. Stocking and medication dosing should be based on the water actually in the tank.
Common questions
Why does the filled weight matter?
Water is heavy: even this small 65 litre tank weighs about 71 kg filled, and a 200 litre tank passes 220 kg. Aquarium stands are built for it; desks, dressers, and older floors may not be. Put the weight estimate against your stand's rating, and spread large tanks across joists where possible.
Is the capacity the same as the water volume for stocking fish?
Not quite. Substrate, rocks, and decor displace water, and the tank is rarely filled to the brim, so the swimming volume is usually 5 to 10 percent below the calculated capacity. Use the lower figure when judging stocking levels or dosing treatments.
Estimates only, based on outside dimensions, water at 1 kg per litre, and a 10 percent allowance for glass and contents. Actual capacity and weight vary with glass thickness, fill level, and equipment. Confirm load ratings with your stand and flooring before filling a large tank. Mississippi Maple accepts no liability for damage or decisions made using this calculator.