Watts to BTU/hr Calculator
Convert watts or wattage into the equivalent heat rate in BTU per hour. This is most direct for electric resistance heaters; heat pumps and air conditioners need an efficiency rating to relate electrical input to delivered heating or cooling.
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BTU per hour = watts × 3.412141633. For example, 1,000 W × 3.412141633 = about 3,412 BTU/hr, and 1,500 W equals about 5,118 BTU/hr.
Watts to BTU/hr conversion chart
Use these common wattage-to-BTU values for an equivalent heat rate. Each result uses BTU/hr = watts × 3.412141633 and is rounded to the nearest whole BTU/hr.
| Watts | BTU per hour |
|---|---|
| 100 W | 341 BTU/hr |
| 250 W | 853 BTU/hr |
| 500 W | 1,706 BTU/hr |
| 750 W | 2,559 BTU/hr |
| 1,000 W | 3,412 BTU/hr |
| 1,500 W | 5,118 BTU/hr |
| 2,000 W | 6,824 BTU/hr |
| 3,000 W | 10,236 BTU/hr |
This table converts a power rate, not energy used over time. Although people often shorten BTU per hour to “BTU,” heating and cooling capacity is normally a BTU/hr rating.
Worked example: 1,500 watts to BTU per hour
Multiply 1,500 W by 3.412141633. The result is 5,118.21 BTU/hr, which rounds to 5,118 BTU/hr. That is the approximate heat output of a 1,500 W electric resistance heater while its heating element is running.
Runtime still controls energy use and cost: a 1,500 W heater running for one hour uses 1.5 kWh. Use the related space-heater running-cost calculator when you want dollars rather than a power conversion.
Electrical watts are not an AC or heat pump’s output watts
For a resistance heater, nearly all electrical input becomes indoor heat, so this direct conversion is useful. An air conditioner or heat pump moves heat instead. Its delivered cooling or heating capacity can be several times the electrical input, so multiplying its plug watts by 3.412 does not tell you its rated capacity.
For AC equipment, use the manufacturer’s BTU/hr rating and EER, SEER or COP when estimating electrical draw and running cost. A 12,000 BTU/hr air conditioner is called a one-ton unit, but it does not normally draw the 3,517 electrical watts represented by a simple heat-rate conversion.
BTU versus BTU per hour
A BTU is an amount of energy. Watts and BTU per hour are power rates, so BTU/hr is the matching unit for a watts conversion. Equipment labels and everyday searches often say “BTU” when they mean BTU/hr.
To convert total watt-hours into a quantity of BTU, multiply watt-hours by 3.412141633 instead. Keep the time basis consistent: watts convert to BTU/hr, while watt-hours convert to BTU.
Frequently asked questions
How many BTU per hour is 1,000 watts?
About 3,412 BTU/hr. Multiply 1,000 W by 3.412141633.
How many BTU per hour is a 1,500 watt heater?
About 5,118 BTU/hr while the element is running. A 1,500 W heater also uses 1.5 kWh for each full hour of operation.
How many watts is 12,000 BTU per hour?
As an equivalent heat rate, 12,000 BTU/hr is about 3,517 W. That is not the electrical input of a typical 12,000 BTU/hr air conditioner because an AC moves heat and uses less input power according to its efficiency.
Is wattage to BTU the same for heaters and air conditioners?
No. It is a direct heat-rate conversion for electric resistance heaters. For an air conditioner or heat pump, use the rated BTU/hr output and efficiency specification to estimate electrical watts.
Is BTU the same as BTU per hour?
No. BTU is energy, while BTU per hour is a power rate. Watts convert directly to BTU/hr; watt-hours convert to BTU.
How many BTU per hour are in one ton of cooling?
One refrigeration ton is 12,000 BTU/hr. That equals about 3,517 W as a heat rate, not necessarily the equipment’s electrical input.
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