How much does it cost to run an aquarium?
About $9.95 a month on the typical usage below, at the U.S. average $0.1816/kWh. Set your own rate and usage and the figure updates instantly.
A heated tank's combined heater, filter and light run many hours a day; bigger tanks cost more.
Running an aquarium at 150W running 50% of 24 h costs about
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An aquarium isn't one appliance, it's three running at once: a heater, a filter pump, and a light, and the heater is almost always the one driving the bill. A typical tank heater is around 150 watts, but it doesn't run constantly — it cycles on and off to hold the water at a set temperature, so the real cost depends on your room temperature and tank size as much as the heater's wattage rating.
Where people get surprised is the pump and light, which most owners never turn off. A filter pump running 24/7 and a light running 10-12 hours a day add up quietly in the background, month after month, even though neither one looks like a big draw on its own. Add a heated tank's default 12 hours of heater runtime on top of that, and a modest setup can end up costing more per month than people expect from something that just sits in the corner of a room.
What drives the cost of running an aquarium
- Heater wattage and how often it cycles on — a bigger tank or a colder room means the heater runs more to hold temperature
- Filter pump running nearly 24/7 — low wattage individually, but it never turns off, so the hours add up fast
- Light schedule — most tanks run lighting 8-12 hours a day on a timer, which adds a steady daily cost on top of the heater and pump
How to cut it
- Keep the tank out of drafts and away from AC vents or cold windows so the heater doesn't have to fight room temperature swings
- Use a tight-fitting lid or canopy — it cuts heat loss from the water surface, so the heater cycles on less often
- Switch the light to LED if it isn't already; LED aquarium lights use a fraction of the wattage of older fluorescent or halide fixtures
- Put the light on a timer instead of running it all day — 8-10 hours is plenty for most planted or fish-only tanks
Data basis
- Electricity price
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.B, June 2026 year to date, released 2026-08-26. Retrieved 2026-09-11. Average residential revenue per kWh. A benchmark average, not a utility tariff — it excludes the fixed charges, tiers, time-of-use windows, taxes and fuel adjustments on a real bill.
- Appliance energy
- A representative running power for an aquarium, compiled from published manufacturer specifications and public appliance-energy guidance, and presented as a typical figure with the usual range shown above. It is not a measurement of your unit, and we do not claim a single primary source for it — the nameplate on your appliance, or an hour with a plug-in energy meter, beats any typical figure we can publish.
- Usage model
- Cycling load — 150W running 50% of 24 h
- International prices
- rounded typical household tariffs for each market, in that market's own currency unless the row says US$ equivalent. These are planning benchmarks with no single primary source; enter the per-kWh price from your own bill for an accurate figure.
- Last reviewed
- 20 August 2026. Next scheduled review 20 February 2027.
- Corrections
- Think a figure is wrong? Tell us at corrections@watt-dollar.com and see our corrections policy.
Common questions
How much does it cost to run an aquarium per month?
On the assumption shown above — 150W running 50% of 24 h — an aquarium costs about $9.95 a month, or $119 a year, at $0.1816/kWh. That price is the U.S. average; set your own rate and usage above and the figure updates.
How is that worked out?
Running power x hours connected x the share of that time the motor actually runs. At 150W running 50% of 24 h that is 1.80 kWh a day, which at $0.1816/kWh costs $0.33 a day.
How can I cut the cost of running an aquarium?
Keep the tank out of drafts and away from AC vents or cold windows so the heater doesn't have to fight room temperature swings As a worked example: getting the run share down from 50% to 40% takes it from $119 to $95.45 a year, about $23.86 less.
Does a bigger tank always cost more to run?
Usually, but not in a straight line. A bigger volume of water holds temperature more steadily than a small tank, so per gallon, a large heated aquarium can actually be more efficient than a small one — the heater cycles less often relative to its size. What drives the cost up with bigger tanks is usually a bigger pump and more powerful lighting, not the heater alone.
Do I need to count the heater's full wattage, or just when it's cycling on?
Just when it's on. A heater's wattage rating is its draw while actively heating, but it cycles off once the water hits temperature, so it isn't running 100% of the time like the pump or light usually are. That's why the calculator asks for hours per day for the heater separately — it's rarely running all 24.