Water heating · May 2026 rates
Electric tankless water heater electricity cost calculator
Estimate the electricity cost of heating a daily volume of water without assigning a storage-tank standby schedule.
Hot-water energy model
Calculate water-heating electricity cost
This is a transparent planning model, not a reproduction of the federal UEF test procedure. The effective factor is user-editable so you can match a specific product rating, measured annual use, or a different modeling assumption. Inlet temperature, standby losses, draw timing, ambient conditions, and controls can change actual consumption.
Default model
Editable assumptions
The calculator starts at 40 gallons/day, a 70°F temperature rise, and an effective factor of 0.98. These are planning defaults, not a claim about every product.
Primary reference
DOE water-heating guidance
U.S. Department of Energy — Consumer Water Heaters ↗
PowerCostAtlas is independent and is not endorsed by DOE.
How to make the estimate more useful
Use a realistic daily hot-water volume, your local cold-water temperature to estimate temperature rise, and the electricity rate from your bill. If a product has an EnergyGuide annual-kWh estimate, compare that figure with the calculator's annual result and adjust the effective factor if you want the model to reproduce the product's published use.
Compare heat-pump and resistance water heating with the same hot-water load.