Estimate only. Your bill's actual rate and how often the thermostat turns the heater on change the real cost.
How the cost is calculated
- Cost per hour: heater watts ÷ 1,000 × your state's average residential electricity price (EIA, Table 5.6.B).
- Electricity per month: watts ÷ 1,000 × hours on per day × days × the share of time it heats at full power.
- Cost per month: that electricity × the same price.
Why 1,500 W
It is the most common maximum power for portable electric heaters: in a 2023 test of 27 heaters bought at retail by Consumer Product Safety Commission staff, 23 had a measured maximum of 1,500 W (CPSC). Use the watts on your heater's label. On a low setting it uses less.
The thermostat changes the cost
A heater with a thermostat turns its heating element off when the room reaches the set temperature, so it does not draw full power the whole time it is on. If you do not know the share, start at 100% for the highest cost and try 50% to see a cycling heater in a small room.
Use it safely
The CPSC advises keeping portable heaters at least 3 feet from drapes, furniture, bedding and anything else that can burn, and plugging them directly into a wall outlet, never into an extension cord or power strip (CPSC).
To compare with other appliances, use the appliance energy cost calculator, and see electricity rates by state.