How much does it cost to run an aquarium heater?
An aquarium heater costs about 0.5¢ per hour, 13¢ a day, $3.94 a month and $47 a year at typical use (24 hours a day) and the U.S. average rate of 17.99¢/kWh. Heaters cycle with the thermostat; in a 70°F home a heater runs about 25-40% of the time.
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Cost by setting
| Setting | Watts | Per hour | Per day | Per month | Per year |
|---|---|---|---|---|---|
| 25-50 W (5-10 gal) | 50 | 0.3¢ | 6.5¢ | $1.97 | $24 |
| 100 W (20-30 gal) | 100 | 0.5¢ | 13¢ | $3.94 | $47 |
| 200 W (50-55 gal) | 200 | 1.1¢ | 26¢ | $7.89 | $95 |
| 300 W (75 gal) | 300 | 1.6¢ | 39¢ | $11.83 | $142 |
At 24 hours a day and 17.99¢/kWh.
Cost by hours of use
| Hours per day | kWh/day | Per day | Per month | Per year (all year) |
|---|---|---|---|---|
| 1 hour | 0.03 | 0.5¢ | $0.16 | $2 |
| 2 hours | 0.06 | 1.1¢ | $0.33 | $4 |
| 4 hours | 0.12 | 2.2¢ | $0.66 | $8 |
| 8 hours | 0.24 | 4.3¢ | $1.31 | $16 |
| 12 hours | 0.36 | 6.5¢ | $1.97 | $24 |
| 24 hours | 0.72 | 13¢ | $3.94 | $47 |
Cost to run an aquarium heater in every state
The same aquarium heater costs $32 a year in North Dakota and $114 in Hawaii, at each state's average residential rate (12 months ending July 2026).
| State | Rate | Per hour | Per month | Per year |
|---|---|---|---|---|
| North Dakota | 12.32¢ | 0.4¢ | $2.70 | $32 |
| Idaho | 12.65¢ | 0.4¢ | $2.77 | $33 |
| Nebraska | 12.86¢ | 0.4¢ | $2.82 | $34 |
| Louisiana | 12.99¢ | 0.4¢ | $2.85 | $34 |
| Utah | 13.32¢ | 0.4¢ | $2.92 | $35 |
| Nevada | 13.36¢ | 0.4¢ | $2.93 | $35 |
| Arkansas | 13.43¢ | 0.4¢ | $2.94 | $35 |
| Tennessee | 13.56¢ | 0.4¢ | $2.97 | $36 |
| Oklahoma | 13.70¢ | 0.4¢ | $3.00 | $36 |
| Montana | 13.84¢ | 0.4¢ | $3.03 | $36 |
| Kentucky | 13.92¢ | 0.4¢ | $3.05 | $37 |
| Missouri | 13.95¢ | 0.4¢ | $3.06 | $37 |
| Wyoming | 14.01¢ | 0.4¢ | $3.07 | $37 |
| Washington | 14.12¢ | 0.4¢ | $3.09 | $37 |
| Iowa | 14.13¢ | 0.4¢ | $3.10 | $37 |
| South Dakota | 14.20¢ | 0.4¢ | $3.11 | $37 |
| Mississippi | 14.77¢ | 0.4¢ | $3.24 | $39 |
| North Carolina | 14.77¢ | 0.4¢ | $3.24 | $39 |
| Kansas | 15.09¢ | 0.5¢ | $3.31 | $40 |
| Georgia | 15.12¢ | 0.5¢ | $3.31 | $40 |
| New Mexico | 15.32¢ | 0.5¢ | $3.36 | $40 |
| Florida | 15.39¢ | 0.5¢ | $3.37 | $40 |
| Arizona | 15.40¢ | 0.5¢ | $3.37 | $40 |
| West Virginia | 15.48¢ | 0.5¢ | $3.39 | $41 |
| Oregon | 15.50¢ | 0.5¢ | $3.40 | $41 |
| South Carolina | 15.64¢ | 0.5¢ | $3.43 | $41 |
| Texas | 15.96¢ | 0.5¢ | $3.50 | $42 |
| Minnesota | 16.22¢ | 0.5¢ | $3.55 | $43 |
| Alabama | 16.44¢ | 0.5¢ | $3.60 | $43 |
| Virginia | 16.48¢ | 0.5¢ | $3.61 | $43 |
| Colorado | 16.58¢ | 0.5¢ | $3.63 | $44 |
| Indiana | 16.94¢ | 0.5¢ | $3.71 | $45 |
| Delaware | 17.79¢ | 0.5¢ | $3.90 | $47 |
| Ohio | 18.25¢ | 0.5¢ | $4.00 | $48 |
| Wisconsin | 18.74¢ | 0.6¢ | $4.11 | $49 |
| Illinois | 18.79¢ | 0.6¢ | $4.12 | $49 |
| Pennsylvania | 20.70¢ | 0.6¢ | $4.54 | $54 |
| Maryland | 21.03¢ | 0.6¢ | $4.61 | $55 |
| Michigan | 21.05¢ | 0.6¢ | $4.61 | $55 |
| New Jersey | 23.78¢ | 0.7¢ | $5.21 | $63 |
| Vermont | 23.80¢ | 0.7¢ | $5.22 | $63 |
| District of Columbia | 24.20¢ | 0.7¢ | $5.30 | $64 |
| New Hampshire | 26.67¢ | 0.8¢ | $5.84 | $70 |
| Alaska | 26.85¢ | 0.8¢ | $5.88 | $71 |
| Connecticut | 27.99¢ | 0.8¢ | $6.13 | $74 |
| New York | 28.39¢ | 0.9¢ | $6.22 | $75 |
| Rhode Island | 29.27¢ | 0.9¢ | $6.41 | $77 |
| Maine | 29.31¢ | 0.9¢ | $6.42 | $77 |
| Massachusetts | 30.43¢ | 0.9¢ | $6.67 | $80 |
| California | 32.99¢ | 1.0¢ | $7.23 | $87 |
| Hawaii | 43.51¢ | 1.3¢ | $9.54 | $114 |
How to cut the cost
- Use a lid; open tops lose far more heat to evaporation.
- Lower set point to 76-78°F for most tropical fish.
- Insulate the back and sides with foam board on cold walls.
- Use two smaller heaters for redundancy without raising total watts.
Cheaper ways to get the job done
Cuts heat loss through the glass.
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Compare with similar appliances
| Appliance | Watts | Typical use | Per month | Per year |
|---|---|---|---|---|
| Aquarium heater | 100 | 24 hours a day | $3.94 | $47 |
| Aquarium | 135 | 24 hours a day | $6.39 | $77 |
| Reptile heat lamp | 100 | 12 hours a day | $6.57 | $79 |
| Under-tank heater | 20 | 24 hours a day | $1.84 | $22 |
| Heated pet bed | 6 | 24 hours a day for 7 months a year | $0.79 | $6 |
| Pet water fountain | 2 | 24 hours a day | $0.26 | $3 |
Head-to-head comparisons
Frequently asked questions
How much does it cost to run an aquarium heater per hour?
An aquarium heater drawing 100 watts uses 0.03 kWh per hour while running (30% duty cycle). At the U.S. average of 17.99¢/kWh that's 0.5¢ per hour. In North Dakota (12.32¢) it's 0.4¢. In Hawaii (43.51¢) it's 1.3¢.
How much does it cost to run an aquarium heater per month?
At typical use (24 hours a day), an aquarium heater costs about $3.94 a month and $47 a year, at the U.S. average rate. Enter your ZIP in the calculator above for your utility's rate.
How many watts does an aquarium heater use?
Most aquarium heaters use 25 to 500 watts, depending on the setting (25-50 w (5-10 gal) 50 W, 100 w (20-30 gal) 100 W, 200 w (50-55 gal) 200 W, 300 w (75 gal) 300 W). Check the label on the back or bottom for your model's exact rating.
How many kWh does an aquarium heater use?
About 0.72 kWh a day and 263 kWh a year at typical use (24 hours a day).
Does an aquarium heater use a lot of electricity?
No. At about 263 kWh a year it's a small share (2.5%) of the average U.S. home's 10,492 kWh.
Is it cheaper to run an aquarium heater or an aquarium?
At typical use, an aquarium heater costs about $47 a year versus $77 for an aquarium. So the aquarium heater is cheaper by about $29 a year. Use the comparison table above to compare them at your own settings.
How can I lower the cost of running an aquarium heater?
- Use a lid; open tops lose far more heat to evaporation.
- Lower set point to 76-78°F for most tropical fish.
- Insulate the back and sides with foam board on cold walls.
Rates updated 2026-10-21: EIA data through July 2026. Typical wattage and usage reviewed against DOE, ENERGY STAR and manufacturer specs. Methodology.