How Many Watts Of Electricity Does A Fish Tank Heater Use And Do They Raise Your Bills?

In this article, we’ll take a look at exactly how much power and electricity your aquarium heater uses every day and also explore how much it will cost you each year to run your aquarium heater.

Our Top Rated Aquarium Heaters

Here is what you’ll learn;


Feel free to also check out our guide on how to use an aquarium heater where we answer many more questions and walk you through the installation and setup of your aquarium heater.

How Many Watts Are Used By An Aquarium Heater

Aquarium heaters use between 25-250 Watts and will use between 219-2019 kWh per year depending on the size of the heater you are using.

What Size Heater Do You Need For Your Fish Tank (Watts)

You can use the fish tank heater size chart below to help you determine what size of an aquarium heater (Wattage) you need for the size of your tank in gallons or liters.

The chart below will also show you how many Watts your aquarium heater will use, how much energy it will use each year and how much it will cost you.

Aquarium Heater Size Chart

Tank Size Watts KwH (Annual) (USD) Yearly Cost UK (EUR) Yearly Cost
5 Gallons/20 Liter 25 219 30.66 48.18
10 Gallons/40 Liter 50 438 61.32 96.36
20 Gallons/75 Liter 50 438 61.32 96.36
25 Gallons/100 Liter 75 657 91.98 144.54
40 Gallons/150 Liter 100 876 122.64 192.72
50 Gallons/200 Liter 150 1314 183.96 289.08
65 Gallons/250 Liter 200 1752 245.28 385.44
75 Gallons/300 Liter 250 2190 306.6 481.8

Further Reading: Best aquarium heater for a 10 gallon tank

Fish Tank Heater Energy Consumption (Annually)

To Find out how much power/energy your fish tank heater will use each year, you can use the following formula (or look at the chart above)

Multiply the total watts by the total number of hours the heater will be running per day, multiply that by 365 days for the year. Then divide the answer by 1000 to get the kWh

For example:

Filter (25 Watts × 24 hours/day × 365 days/year) ÷ 1000 = 219kWh

Fish Tank Heater Electricity Cost Calculator (UK & US)

To determine how much it will cost to run your fish tank heater all year, you can use the following formula to calculate the cost (or look at the chart above)

Take kWh for the size of your heater and multiply that by your electrical provider’s kWh rate.

For example:

If the average US kWh rate is 14 cents, then it would cost $30.66 to run a 25W aquarium heater all year long.

$0.14 * 219 = $30.66

Here is a very helpful resource that they update monthly on electricity rates broken down by every state.

Do Fish Tank Heaters Use A Lot Of Electricity

Compared to other appliances used in your house, fish tank heaters use a lot of electricity, considering how small they are.

To compare:

A standard fridge uses about 2.4 kWh each day. Where a 50W fish tank heater uses about 1.2 kWh each day.

So if you happened to be using two small 50W heaters, it would use as much power as your fridge!

That being said, the overall cost to run a 50W fish tank heater for the entire year is just over $60.00 or $5 each month.

In the end, it’s all relative.

Do Fish Tank Heaters Raise Your Electricity Bill

Yes, using a fish tank heater will raise your electricity bill each month. However, the total cost is minimal when you break it down to a monthly cost.

In the example above, a 50Watt fish tank, the heater would only cost $61.32 (USD) for the entire year and only $5.11 (USD) each month.

At the end of the day, I hope the cost of a fish tank heater doesn’t prevent you from getting into the hobby; it’s a great one!

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