Add a blanket and a heater to the home list to compare them side by side.
How to work out what an appliance costs to run
Every electricity bill charges for energy in kilowatt-hours (kWh). To find the cost of running an appliance, you need three numbers: its power in watts, how long it runs, and your price per kWh. Multiply watts by hours and divide by 1,000 to get kWh, then multiply by your rate. A 1500 W space heater running for one hour uses 1.5 kWh; at 17 cents per kWh that costs about 26 cents. KwhCalc does the arithmetic for you and scales it to a day, an average month and a full year, taking into account how many days a week you use the appliance.
Getting accurate numbers
The wattage on a label is usually the maximum. Appliances with thermostats or compressors, such as fridges, freezers, heaters on a thermostat and air conditioners, switch on and off, so their average draw is much lower than the label. A plug-in energy monitor is the best way to measure real use over a day or a week. For your rate, look at the price per kWh on your bill and include delivery or distribution charges that are also charged per kWh. Time-of-use plans charge different prices at different times of day, so use the rate for the hours you run the appliance.
Where the money goes
Anything that makes heat or cold uses the most energy: space heaters, clothes dryers, ovens, kettles, hot tubs and air conditioners. Electronics use less per hour but run for long periods, and devices left on standby add up across a home. LED bulbs use around a sixth of the power of old incandescent bulbs for the same light. Use the home list to add up your main appliances and compare the monthly totals with your bill; heating and hot water are often the largest part.
Saving money in winter
Heat the room you are in rather than the whole house, close doors and curtains, and lower the thermostat by a degree or two. Warming yourself with an electric blanket or heated throw costs a fraction of heating a room. Run the dryer with full loads, or dry clothes on a rack. Your appliance list and rate are stored only in this browser.
Frequently asked questions
Is it safe to leave an electric blanket on all night?
Many modern blankets have timers and overheat protection; follow the maker’s instructions.
Do heated throws cost the same?
Throws often use 100–150 W, still far less than a heater.
Should I turn the heating down?
Lowering the thermostat at night saves the most; a blanket keeps you comfortable.
Is KwhCalc free?
Yes, with no sign-up or ads.
Is my list saved?
Yes, in this browser only.