Aquarium guides

Quick answers to the questions behind every tank: how big it really is, what heater it needs, how much sand to buy and what your salinity reading means. Every chart is worked out with the same formulas as our calculators.

• Aquarium tank sizes chart

  Fish tank sizes chart: dimensions in inches and cm, gallons, litres and water weight for 2.5–125 gallon tanks, plus what a 20 long, 29, 40 breeder, 55 and 75 hold.

• What size heater do I need?

  Aquarium heater wattage charts by tank size and room temperature in gallons and litres, why 5 watts per gallon fails big tanks, and when to use two heaters.

• How much substrate do I need?

  How many pounds of aquarium sand or gravel, or litres of aquasoil, for common tank sizes at 1–3 in (3–8 cm) deep, with the formula and depth advice.

• Specific gravity to ppt chart

  Specific gravity to ppt chart and back for reef tanks: 25/25 °C readings and 60 °F hydrometers in warm water, from the UNESCO seawater equation.

Want a number for your own tank instead? All calculators.