Aquarium Heater Calculator
Find the right heater wattage for your tank size and room temperature.
How it works
A rule of thumb is 1 watt per litre for a small temperature rise. For larger rises (cold rooms) use 1.5 watts per litre. Required watts ≈ Volume (L) × factor, rounded up to the nearest available heater, and split across two heaters in large tanks.
Advertisement
Formula & Method
A rule of thumb is 1 watt per litre for a small temperature rise. For larger rises (cold rooms) use 1.5 watts per litre. Required watts ≈ Volume (L) × factor, rounded up to the nearest available heater, and split across two heaters in large tanks.
Example Calculation
A 100 L tank in a moderately heated room needs roughly a 100 W heater; in a cold room, a 150 W (or two 75 W) heater is safer.
Frequently Asked Questions
Should I use two heaters?
In tanks over 200 L, two smaller heaters give redundancy and more even heat, and prevent disaster if one fails on.
What temperature for tropical fish?
Most tropical community fish do well at 24-26C. Always match your specific species' needs.