How much does an aquarium cost per month in Illinois?

About $9.80 a month, assuming 150 W at a 45% duty cycle, 24 hours a day, 365 days a year at 19.89¢/kWh.

How many kilowatt-hours does an aquarium use?

Roughly 591 kWh a year under these assumptions, or 0.07 kWh for every hour it runs.

Is that expensive compared with other states?

Illinois has the 16th most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $108 a year.

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Cost to run an aquarium in Illinois (June 2026 rates)

At 19.89¢ per kilowatt-hour — Illinois's average residential price in June 2026 — running an aquarium costs $118 a year. That is 8% more than the national average of $108. Illinois's residential rate is up 8.7% from June 2025, which moves this appliance from $108 to $118 a year.

Per hour: 1.3¢
Per day of use: 32.2¢
Per month: $9.80
Per year: $118

Assumption: 150 W at a 45% duty cycle, 24 hours a day, 365 days a year — 591 kWh a year. A 55-gallon tank: heater, filter and light combined, averaged over a day. Use the calculator to swap in the numbers from your own model.

How Illinois compares

Illinois pays 19.89¢/kWh, the 16th most expensive residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $9.17 more a year than the typical U.S. household pays for the same use. Running the same aquarium costs $77.52 a year in Nevada and $312 in Hawaii, so where you live changes this bill by $234 a year.

State	Rate	Per month	Per year
Delaware	19.29¢	$9.51	$114
Wisconsin	19.56¢	$9.64	$116
Illinois	19.89¢	$9.80	$118
Pennsylvania	21.73¢	$10.71	$128
Maryland	21.84¢	$10.76	$129

States ranked by average residential price, cheapest first. See all 51 states for an aquarium.

What else costs about the same in Illinois

Gaming pc$116 a year in IL Well pump$109 a year in IL Dehumidifier$107 a year in IL

Cutting the number down

The heater is nearly all of it, and its runtime depends on the room. A tank in a cool room costs more to keep warm.
Insulating the back and sides of the tank cuts heater runtime without changing the view.
A lid limits evaporative heat loss, which is the main way an open tank sheds the warmth you paid for.

Questions

How much does an aquarium cost per month in Illinois?: About $9.80 a month, assuming 150 W at a 45% duty cycle, 24 hours a day, 365 days a year at 19.89¢/kWh.
How many kilowatt-hours does an aquarium use?: Roughly 591 kWh a year under these assumptions, or 0.07 kWh for every hour it runs.
Is that expensive compared with other states?: Illinois has the 16th most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $108 a year.