How Much Does a Tankless Water Heater Cost to Run?
A tankless water heater costs approximately $832/year to run at $0.19/kWh. That is $69.35/month or $4.560/hour.
💰 Tankless Water Heater Running Cost Calculator
Based on 24000W rated power. Actual varies by model and usage.
Tankless Water Heater Cost at Different Rates
| Rate | Monthly | Annual |
|---|---|---|
| $0.08 | $29.17 | $350 |
| $0.10 | $36.50 | $438 |
| $0.12 | $43.83 | $526 |
| $0.16 | $58.42 | $701 |
| $0.20 | $73.00 | $876 |
| $0.25 | $91.25 | $1,095 |
| $0.30 | $109.50 | $1,314 |
| $0.35 | $127.75 | $1,533 |
Electricity cost to run a Tankless Water Heater
A typical Tankless Water Heater draws 24,000 watts when running and operates roughly 0.5 hours per day on average. That works out to 12.00 kWh per day, 365 kWh per month, and approximately 4,380 kWh per year.
At the US-average residential rate of 18.8 cents per kWh (EIA April 2026), the Tankless Water Heater costs roughly $823 per year to operate. In cheap-power states like North Dakota or Idaho at about 12.5 cents, it is closer to $556. In expensive states like Massachusetts or New York at about 29.5 cents, it climbs to $1292. In Hawaii at 46.6 cents per kWh, the annual cost is approximately $2041.
Annual cost by state rate
| Rate scenario | Rate (c/kWh) | Annual kWh | Annual cost |
|---|---|---|---|
| North Dakota, Idaho (cheapest) | 12.5 | 4,380 | $556 |
| Texas, Florida | 16.0 | 4,380 | $701 |
| US national average | 18.8 | 4,380 | $823 |
| Massachusetts, New York | 29.5 | 4,380 | $1292 |
| California | 35.3 | 4,380 | $1546 |
| Hawaii (most expensive) | 46.6 | 4,380 | $2041 |
Frequently asked questions
How much electricity does a Tankless Water Heater use?
A typical Tankless Water Heater uses about 12.00 kWh per day running 0.5 hours at 24,000W. That works out to roughly 365 kWh per month and 4,380 kWh per year. Your actual use will vary with how often you run it.
How much does it cost to run a Tankless Water Heater per month?
At US-average electricity rates (18.8 cents/kWh), running the Tankless Water Heater costs about $68.62 per month. In low-rate states it can be as little as $45.63; in high-rate states like California, expect closer to $128.84 per month.
What is the annual cost of running a Tankless Water Heater?
Annual operating cost at US-average rates: approximately $823 per year. The range across US states is roughly $438 (cheapest) to $2041 (Hawaii).
How can I reduce the cost of my Tankless Water Heater?
Check whether your utility offers a time-of-use plan that aligns with this appliance use pattern.
What watt rating should I expect for a Tankless Water Heater?
Typical running wattage for a Tankless Water Heater is around 24,000 watts. Specific models vary; check the nameplate label on your unit for exact figures. Common variation is plus-or-minus 20 percent of the typical value.
Tankless Water Heater Energy Usage Explained
A tankless water heater consumes 24000W. At 0.5 hours/day for 365 days/year, that is 4,380 kWh annually, about 41.7% of average US household usage (10,500 kWh).
How to Calculate Running Cost
Cost = (Watts ÷ 1000) × Hours × Rate
For your tankless water heater: (24000W ÷ 1000) × 0.5 hrs × $0.19/kWh = $2.28/day.
Tips to Reduce Costs
Use time-of-use electricity plans for off-peak rates ($0.05–$0.10/kWh overnight). Upgrade to Energy Star certified models. Use smart plugs or timers. Check rates in your state with our Electricity Cost Calculator.
Disclaimer: Estimates based on rated wattage. Actual consumption varies by model, age, and usage patterns.