Aquarium chart
Aquarium Heater Wattage Chart by Tank Size
Use this aquarium heater wattage chart to compare tank gallons, temperature rise, and suggested heater watts before opening the calculator. Use the chart as a quick planning reference, then use Aquarium Heater Size Calculator when you need exact numbers for your own inputs.
Chart values
| Tank size | 5 °F rise | 10 °F rise | 15 °F rise |
|---|---|---|---|
| 10 gallons | 50 W | 50 W | 75 W |
| 20 gallons | 75 W | 100 W | 150 W |
| 40 gallons | 125 W | 200 W | 300 W |
| 55 gallons | 175 W | 275 W | 425 W |
| 75 gallons | 225 W | 375 W | 575 W |
Calculated from the existing aquarium heater size calculator inputs: gallons, room temperature, and target water temperature.
How to use this chart
Choose the tank size row, then use the temperature-rise column closest to the difference between room temperature and target water temperature.
When to use the calculator instead
Use the calculator when your measurements, rates, room conditions, local prices, tank setup, loan terms, or classroom routine do not match the simple chart rows. The calculator lets you adjust the inputs instead of forcing your situation into a rough example.
Examples from this chart
Worked example
A 20 gallon tank that needs to stay 10 °F above room temperature maps to about 100 W. If the room gets colder in winter, use the calculator with the colder room temperature.
Limitations and assumptions
Values use the aquarium heater size calculator formula and round heater wattage up to the next 25 W. Real tanks can vary with lids, drafts, flow, and heater placement.
Save or share this chart
You can print this page, save the tall image for planning, or link to the page from a blog post, classroom resource, forum answer, or project checklist so readers can open the calculator too.
Chart questions
Chart questions
Can I use two smaller aquarium heaters instead of one?
For larger tanks, two smaller heaters placed apart can improve heat distribution and add redundancy.
Should I size the heater from display gallons?
Use actual water volume when possible because substrate, rock, and decorations reduce real gallons.