Aquarium Heater Sizing Calculator

Heater wattage from tank volume and temperature delta.

Tank Volume (gallons)

Room Temperature (°F)

Target Water Temp (°F)

Insulation Quality

Tab to move between fields

Recommended Wattage

Calculated Wattage60

Number of Heaters1

Watts per Heater75

Temperature Delta (°F)10

Est. Monthly Cost ($)$3.51

How to Use This Calculator

How the result changes with Room Temperature (°F)

Tank Volume (gallons): Total water volume of your aquarium in US gallons.
Room Temperature (°F): Average ambient temperature of the room where the aquarium is kept.
Target Water Temp (°F): Desired water temperature. Tropical fish typically need 75-82°F.
Insulation Quality: 1 = Poor (drafty room, near window), 2 = Average, 3 = Well-insulated.

Recommended Wattage: Nearest standard heater size in watts.
Calculated Wattage: Exact calculated wattage before rounding to standard size.
Number of Heaters: Tanks over 75 gallons benefit from two heaters for redundancy.
Watts per Heater: Wattage for each individual heater unit.
Temperature Delta (°F): Difference between target water temp and room temp.
Est. Monthly Cost ($): Estimated monthly electricity cost at $0.13/kWh with 50% duty cycle.

Identify Input Parameters
4 parameters
Tank Volume (gallons) = 20, Room Temperature (°F) = 68, Target Water Temp (°F) = 78, Insulation Quality = 2 = 4 input(s) provided
Calculate Recommended Wattage
Recommended Wattage = commonSizes[commonSizes.length - 1]
75 = 75
Calculate Calculated Wattage
Calculated Wattage = tankVolume * wattsPerGallon * insulationMultiplier
60 = 60
Calculate Number of Heaters
Number of Heaters
1 = 1