How much does it cost to run an aquarium?
We've pre-filled an typical aquarium below. Set your electricity rate and adjust the hours to match how you use yours — the cost updates instantly.
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
Common questions
How much does it cost to run an aquarium per month?
At a typical 150W and about 12 hours a day, an aquarium costs roughly $9.18 a month at $0.17/kWh. Set your own rate and hours above for an exact figure.
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
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.
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