Calculate aquarium electricity cost per day, month and year from heater, light, filter and pump wattages, using your rate or the US average.
Aquarium Energy Cost Formula
For the heater, which is thermostat controlled and cycles on and off, the calculator applies a duty cycle instead of assuming full wattage all day:
- C is the electricity cost ($)
- W is the device wattage (watts)
- h is the hours the device runs per day
- d is the number of days (30 for a month, 365 for a year)
- R is your electricity rate ($ per kWh)
- DC is the heater duty cycle (%), the share of the day the heating element is actually on
The full setup mode applies the first formula to each piece of equipment (lighting, filter, air pump, and other gear) and the duty cycle version to the heater, then sums everything into a daily, monthly, and yearly total with a per-device breakdown. The single device mode applies the base formula to one item, which is useful for checking whether a specific pump or light is worth upgrading. The quick estimate mode skips wattages entirely and multiplies your tank volume by an illustrative average draw per US gallon: 1.2 W for unheated coldwater tanks, 3.2 W for heated tropical freshwater, 4.0 W for planted tanks with strong lighting, and 6.0 W for saltwater reef tanks. These factors are assumptions, not validated averages for all aquariums; override the factor or use measured itemized power for your setup.
Illustrative Equipment Wattages and Heater Duty Cycles
The first table shows example equipment wattages and calculated monthly energy charges at an assumed $0.17 per kWh. Use the rate on your utility bill. These figures are scenarios, not current national prices or equipment specifications.
| Equipment | Example wattage | Hours per day | Monthly cost at $0.17/kWh |
|---|---|---|---|
| Heater (thermostat cycles) | 50 – 300 W | 24 (about 45% on) | $2.75 – $16.52 |
| LED lighting | 10 – 60 W | 8 – 10 | $0.41 – $3.06 |
| Filter / return pump | 5 – 80 W | 24 | $0.61 – $9.79 |
| Air pump | 2 – 10 W | 24 | $0.24 – $1.22 |
| UV sterilizer | 8 – 25 W | 24 | $0.98 – $3.06 |
| Wavemaker / powerhead | 5 – 40 W | 24 | $0.61 – $4.90 |
A thermostat-controlled heater cycles on and off. The second table calculates costs for assumed duty cycles on a 200 W heater at $0.17 per kWh. The temperature descriptions are qualitative scenario labels, not a calibrated relationship between room temperature and runtime. Measure energy use or runtime to choose a duty cycle.
| Illustrative room scenario | Assumed duty cycle | Effective draw (200 W heater) | Monthly cost at $0.17/kWh |
|---|---|---|---|
| Warm-room scenario | ~35% | 70 W | $8.57 |
| Intermediate scenario | ~45% | 90 W | $11.02 |
| Cool-room scenario | ~60% | 120 W | $14.69 |
| High-duty scenario | ~75% | 150 W | $18.36 |
Example Problems
Example 1: Itemized tropical freshwater setup. You run a 150 W heater at an assumed 45% duty cycle, a 30 W light for 10 hours per day, a 20 W filter, and a 5 W air pump, and you pay $0.17 per kWh.
- Heater: 150 * 24 * 0.45 / 1000 = 1.62 kWh per day
- Light: 30 * 10 / 1000 = 0.30 kWh per day
- Filter: 20 * 24 / 1000 = 0.48 kWh per day
- Air pump: 5 * 24 / 1000 = 0.12 kWh per day
The total is 2.52 kWh per day, which is an average continuous draw of 105 W. Monthly use is 2.52 * 30 = 75.6 kWh, so the monthly cost is 75.6 * 0.17 = $12.85. Yearly use is 919.8 kWh, or $156.37 per year.
Example 2: Quick estimate for a reef tank. You have a 55 gallon saltwater reef and pay $0.15 per kWh. Using the illustrative reef factor of 6.0 W per US gallon, the average draw is 55 * 6 = 330 W. Daily use is 330 * 24 / 1000 = 7.92 kWh. Monthly use is 7.92 * 30 = 237.6 kWh, so the monthly cost is 237.6 * 0.15 = $35.64, and the yearly cost is 2890.8 * 0.15 = $433.62.
FAQ
Why not just multiply heater wattage by 24 hours?
A thermostat-controlled heater draws rated heating power while the element is on. Multiply rated watts by its measured fraction of on-time. The default 45% is only an illustrative assumption; actual duty depends on the equipment and heat loss. Standby power, if relevant, should be included separately.
What uses the most electricity in an aquarium?
The largest consumer depends on the setup. Compare the itemized monthly kWh for the heater, lights and pumps. The tank-size factors are illustrative inputs and do not establish which device uses the most energy.
How can I lower my aquarium’s energy cost?
Compare measured wattage and runtime before changing equipment. Use the single-device mode to compare alternatives at the same operating schedule, while preserving the temperature, oxygenation, flow and lighting your animals and plants require. Follow equipment instructions and aquatic-care guidance when changing the setup.
