Watts to Heat Calculator

Converting Watts to Heat (BTU/h)

Electric heaters convert nearly all input electrical power into heat. One watt of electrical power produces a predictable amount of thermal output, measured in BTU per hour for HVAC and heating equipment.

Formulas

$$BTU/h = W \times 3.41214$$ $$W = \frac{BTU/h}{3.41214}$$

The factor 3.41214 converts watts to British thermal units per hour. Electric resistance heaters are nearly 100% efficient at converting electricity to heat.

Example

A 1500 W space heater produces $1500 \times 3.41214 \approx 5118$ BTU/h of heat. Conversely, a 5000 BTU/h heater draws about 1465 W from the outlet.

Related tools: Watt Converter and BTU to Tons Converter.

Frequently Asked Questions

Why use 3.41214?

One watt equals 3.41214 BTU per hour. This is the standard conversion factor used in HVAC and heating industry calculations.

Are electric heaters 100% efficient?

Yes, in terms of converting electricity to heat. All electrical energy becomes heat. There are no combustion losses unlike gas furnaces.

How many BTU/h do I need to heat a room?

It depends on room size, insulation, climate, and windows. A rough estimate is 20 BTU/h per square foot for moderate climates, but professional load calculations are recommended.

Can I compare a gas furnace BTU rating to an electric heater?

BTU/h ratings are comparable for heat output. However, gas furnaces have combustion efficiency below 100%, while electric heaters convert nearly all input watts to heat.

What is the difference between BTU and BTU/h?

BTU is a unit of energy. BTU/h is a rate of energy transfer (power), analogous to watts. Do not confuse total BTU capacity with BTU/h output rate.

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Watts to Heat Calculator

Converting Watts to Heat (BTU/h)

Formulas

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Frequently Asked Questions

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