Electric Heater Consumption Calculator

Q: How much electricity does a 2kW heater use?

A 2,000W (2kW) heater uses 2 kWh per hour. Running 8 hours/day: 2 × 8 = 16 kWh/day. At $0.15/kWh: $2.40/day or ~$72/month. Heaters with thermostats typically cycle on and off, so actual consumption may be 40–70% of rated power.

Q: Are electric heaters 100% efficient?

Yes — electric resistance heaters convert 100% of electrical energy to heat. But heat pumps (reverse-cycle air conditioners) deliver 2–4 kWh of heat per 1 kWh of electricity, making them 200–400% "efficient" (technically COP 2–4). For the same heating output, a heat pump costs 2–4× less to run than a resistance heater.

Q: What is the cheapest type of electric heater to run?

Reverse-cycle air conditioners (heat pumps) are cheapest to run — COP of 3–5 means 300–500% efficiency. For resistance heaters: all types (oil radiator, fan heater, panel heater, infrared) are equally efficient at 100%. Infrared heats objects directly rather than air, which can feel warmer at a lower air temperature setting.

Find out exactly how much energy and money your electric heater uses. Works for fan heaters, oil radiators, panel heaters, infrared heaters, and storage heaters.

Calculate Heater Running Cost

Heater Power (Watts)

Daily Use (hours)

Thermostat Duty Cycle (%)100% if no thermostat; 50–70% typical for thermostatic heaters

Currency

Rate per kWh

Heater Consumption Results

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Effective Power Draw (W)

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Daily Usage (kWh)

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Cost per Hour (on)

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Daily Cost

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Monthly Cost

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Annual Cost

Formula

Effective power = Watts × (Duty cycle ÷ 100)
Daily kWh = Effective power ÷ 1000 × hours
Cost = kWh × Rate

The duty cycle accounts for thermostat cycling. A heater set to maintain a comfortable room temperature at 60% duty cycle runs 36 out of 60 minutes per hour on average.

Common Heater Wattages

Heater Type	Common Wattages	Best For
Small fan heater	750–1,500 W	Small rooms, quick spot heating
Large fan heater	2,000–3,000 W	Large rooms, rapid heating
Oil-filled radiator	1,000–2,500 W	Sustained background heating, quiet
Panel heater	500–2,000 W	Wall-mounted, programmable
Infrared heater	300–2,000 W	Outdoor areas, spot heating objects
Storage heater (night rate)	1,000–4,000 W (charging)	Off-peak tariff areas

Frequently Asked Questions

How much electricity does a 2kW heater use?

A 2,000W heater uses 2 kWh per hour at full power. With a thermostat at 60% duty cycle: 1.2 kWh/hour effectively. Running 8 hours/day at 60% duty: 9.6 kWh/day. At $0.15/kWh = $1.44/day or ~$43/month. Without thermostat at full blast: 16 kWh/day = $2.40/day or ~$72/month.

Are electric heaters 100% efficient?

Yes — all electric resistance heaters convert exactly 100% of consumed electricity into heat. No energy is lost as exhaust. However, heat pumps achieve a COP (Coefficient of Performance) of 2–5, meaning they deliver 2–5 kWh of heat per 1 kWh electricity consumed by using refrigerant cycles to move heat from outside air. Heat pumps are 2–5× cheaper to run than resistance heaters for the same heat output.

What is the cheapest type of electric heater to run?

For pure resistance heaters: all are identical in running cost (watts × hours × rate). The differences are in responsiveness, heat retention, and convenience. For overall cheapest heating: a reverse-cycle air conditioner (heat pump) is 2–5× cheaper to run. If you must use resistance heating, use a programmable thermostat to minimize duty cycle and heat only occupied rooms.