Aquarium Heater Size Table: Heater wattage by Tank volume
Reference table of heater wattage for Aquarium Heater Size across a range of tank volume values — exact, engine-computed figures you can read off at a glance.
Aquarium Heater Size Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Heater wattage
100
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Aquarium Heater Size Calculator
The Aquarium Heater Size Calculator works out your heater wattage in an instant. Enter tank volume and watts per litre and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the tank volume.
- Enter the watts per litre.
- Read off your heater wattage — the calculator updates automatically, with no button to press.
Formula
The Aquarium Heater Size Calculator uses the formula:
Heater wattage = Tank volume × Watts per litre
Worked example
For example, with tank volume of 100 litres and watts per litre of 1, the heater wattage is 100.
| Tank volume | 100 litres |
|---|---|
| Watts per litre | 1 |
| Heater wattage | 100 |
|---|
Results are estimates for educational use, not professional advice.
Key terms explained
- Volume
- The amount of three-dimensional space an object occupies, measured in cubic units.
Frequently asked questions
About 1 watt per litre is a common guide. A 100-litre tank needs roughly a 100-watt heater.
Cooler rooms or a large gap between room and tank temperature need more, up to 1.5 watts per litre.
For large tanks, two smaller heaters give more even heat and a backup if one fails.
Place it near good water flow, such as by the filter outlet, so heat spreads evenly through the tank.
The Aquarium Heater Size Calculator uses the formula: Heater wattage = Tank volume × Watts per litre. For example, with tank volume of 100 litres and watts per litre of 1, the heater wattage is 100.
Enter the tank volume. Enter the watts per litre. Read off your heater wattage — the calculator updates automatically, with no button to press.
Related guides
How to Calculate Aquarium Heater Size: Formula, Steps & Examples
Learn how to calculate Aquarium Heater Size — the formula explained step by step, with worked examples and a free calculator to check your answer.