Calculate your cost
Start with a representative input, then edit all three numbers.
This setup uses about 405 kWh in a 30-day month.
Please enter valid values within the ranges shown.
| Schedule | Hours/day | Cost/month |
|---|---|---|
| Half runtime | 1.5 | $38.13 |
| Starting point | 3 | $76.26 |
| Longer runtime | 4.5 | $114.39 |
Same 4,500-watt input and 18.83¢/kWh rate; only runtime changes.
The quick formula
4.5 kW × 3 hours × $0.1883 = $2.54 per day
Convert watts to kilowatts, multiply by the active hours used each day, then multiply by the electricity price in dollars per kWh. Multiply the daily result by 30 for the monthly estimate shown above.
How to read this estimate
A conventional electric tank heater has a high-power element that cycles to heat incoming water and replace standby losses. Household hot-water use, rather than the fact that the heater stays connected all day, determines most of the cost.
The starting values keep this page useful before you have a label or meter reading. They do not describe every model, climate, operating mode, or household.
What changes the cost?
- 01
Tank size, element wattage, insulation, and thermostat setting
- 02
Number and length of showers and other hot-water draws
- 03
Incoming water temperature and standby heat loss
Ways to spend less
- Repair hot-water leaks and use efficient showerheads.
- Choose a safe, moderate temperature setting.
- Insulate accessible hot-water pipes where appropriate.