Every aquarium number, worked out for you.
Free calculators for tank volume, stocking, heaters, filters and water changes. Each one shows its working, in gallons and litres. Start with your tank's size:
This tank holds 56.7 US gal (215 L) to the brim, but about 45.9 US gal (174 L) of water once the glass, a 1 in gap, 2 in of substrate and decor are taken off. That is 19% less. Use the real figure for heaters, water treatments and stocking.
- Also
- 174 L · 38.2 UK gal of water
- Inside volume, brim-full
- 53.5 US gal (203 L)
- Weight of the water
- 383 lb (174 kg)
- Footprint
- 624 sq in (4.33 sq ft)
Then work out
How big is it, and what does it need?
Size the tank and the equipment that goes with it.
- VolumeGallons, litres, real water volume, water weightOpen calculator
- DimensionsStandard tank sizes that match, footprintOpen calculator
- HeaterWatts, one heater or twoOpen calculator
- FilterTurnover rate, GPH and L/h rangeOpen calculator
- SubstratePounds, kilograms, litres and bagsOpen calculator
- WeightTotal filled weight, floor loadOpen calculator
- Glass thicknessMinimum glass thickness for each panelOpen calculator
What can live in it, and how do I keep the water right?
Plan the fish, then the routine that keeps them healthy.
Guides
The reasoning behind the numbers, in plain language.
- How to Set Up Your First Aquarium, Step by Step
Tank size, equipment, cycling and first fish, in order, with the numbers for each step.
- Standard Aquarium Sizes Chart
Dimensions, litres and filled weight of every standard tank, US and metric.
- How Many Fish Can I Put in My Tank?
The rules that decide it, and checked example lists for five common tank sizes.
- The Aquarium Nitrogen Cycle, Explained
What happens in the filter, the fishless method day by day, and how to read your tests.
- Aquarium Heater Size Guide
Wattage chart for every standard tank in warm, normal and cold rooms.
Why trust these numbers
The working is shown
Every calculator page gives the formula, a worked example and the source of each rule of thumb. Nothing is a black box.
Tested before release
Each formula is checked against published examples and manufacturers' figures. How we calculate
Real water, not label size
A "55-gallon" tank holds about 46 gallons of water. We work from what is really in the tank, because that is what the fish live in.
Independent
Not owned by any aquarium brand or shop. No sign-up, and your numbers stay in your browser. About us