Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Convert Watts to BTU/hr instantly with an exact, accurate formula -- no sign-up, no ads blocking the result.
This tool converts a power value in watts (W) into British Thermal Units per hour (BTU/hr) -- the unit most heating, ventilation, and air conditioning (HVAC) equipment in the US is rated in. Watts is the standard electrical unit printed on appliance labels, power supplies, and light bulbs; BTU/hr is the unit printed on window air conditioners, space heaters, furnaces, and portable AC units. Both describe the exact same physical quantity -- the rate at which energy is transferred or converted -- just expressed in two different unit systems, so converting between them is a straightforward multiplication, not an estimate.
Type a wattage into the input field. The result panel updates as you type and shows the equivalent in BTU/hr, along with kilowatts, so you have all three common power units side by side without switching tools. There's no unit dropdown to configure for this pair -- if you need the reverse direction, use the BTU to Watts Converter, which runs the same engine starting from BTU/hr.
BTU/hr = Watts × 3.412141633
BTU/hr = W × 3.412141633127942
The constant comes from the internationally recognized definition of the BTU: 1 BTU (International Table) equals exactly 1,055.05585262 joules. Since 1 watt is defined as exactly 1 joule per second, one watt sustained for one hour transfers 3,600 joules -- and 3,600 ÷ 1,055.05585262 works out to 3.412141633127942 BTU. That's where the conversion factor comes from; it isn't rounded or approximated at any step before it reaches the calculator.
A 1,500-watt space heater -- a common wattage for a portable electric heater on a US 15-amp circuit -- puts out about 5,118 BTU/hr of heat. That figure is exactly what you'd compare against a heater's or furnace's published BTU/hr rating to see whether it can adequately heat a room.
| Watts | BTU/hr |
|---|---|
| 100 W | 341.21 |
| 500 W | 1,706.07 |
| 1,000 W | 3,412.14 |
| 1,500 W | 5,118.21 |
| 2,000 W | 6,824.28 |
| 3,000 W | 10,236.42 |
| 5,000 W | 17,060.71 |
The most common reason to convert watts to BTU/hr is sizing or comparing heating and cooling equipment: a space heater, baseboard heater, or portable AC unit is usually labeled in watts on its electrical spec sheet but rated in BTU/hr for its actual heating or cooling output, and the two numbers get compared side by side when picking a unit for a room. It also comes up when reading a furnace or water heater's energy input rating, or when converting a generator's or solar inverter's electrical output into heating-equivalent terms for a rough capacity comparison.
This conversion assumes 100% of the electrical wattage becomes usable heat output, which is true for pure resistive heating (space heaters, baseboard heaters) but not for heat pumps or air conditioners, whose actual heating/cooling BTU/hr output can be several times their electrical wattage input (that ratio is called COP or EER, and isn't part of this calculation). For resistive heaters, this conversion is exact; for heat pump/AC equipment, treat it as the electrical-input side of the picture, not the delivered heating or cooling capacity.
Multiply the wattage by 3.412141633. For example, 1,000 W × 3.412141633 = 3,412.14 BTU/hr. This calculator does that multiplication instantly as you type.
BTU/hr = Watts × 3.412141633127942. The constant is derived from the fixed relationship between the joule (the SI energy unit behind the watt) and the International Table BTU.
1,000 watts equals 3,412.14 BTU/hr.
Yes. It's based on the fixed, internationally defined relationship between the joule and the BTU, not a rounded approximation. The result shown may be rounded for display, but the underlying calculation isn't.
Yes -- the BTU to Watts Converter runs the same conversion in reverse, starting from a BTU/hr value.
They measure the same physical quantity -- the rate of energy transfer, i.e. power -- in two different unit systems. Watts is the SI (metric) unit, defined as one joule per second, and is what's printed on electrical equipment. BTU/hr is a US customary unit used almost exclusively for HVAC equipment ratings (furnaces, air conditioners, space heaters).
Most commonly to compare a space heater's or electric appliance's wattage against a heating or cooling system's BTU/hr rating, since US HVAC equipment is conventionally rated in BTU/hr while the electrical devices that power or compete with it are rated in watts.
The exact watts-to-btu/hr factor is 3.412142 -- multiply to convert forward, or multiply by 0.2930711 to convert btu/hr back to watts. For example, 12.5 watts × 3.412142 = 42.65177 btu/hr, and 7 watts × 3.412142 = 23.88499 btu/hr.
The watt is the SI unit of power: one joule of energy per second. One BTU per hour equals about 0.293071 watts, still common in HVAC equipment ratings.
| Watts | BTU/hr |
|---|---|
| 1 | 3.412142 |
| 2 | 6.824283 |
| 3 | 10.23642 |
| 5 | 17.06071 |
| 10 | 34.12142 |
| 15 | 51.18212 |
| 20 | 68.24283 |
| 25 | 85.30354 |
| 50 | 170.6071 |
| 75 | 255.9106 |
| 100 | 341.2142 |
| 250 | 853.0354 |
| 500 | 1,706.071 |
| 1,000 | 3,412.142 |
How many btu/hr are in 1 watts?
1 watts equals 3.412142 btu/hr.
How many watts are in 1 btu/hr?
1 btu/hr equals 0.2930711 watts.
What is 60 watts in btu/hr?
60 watts equals 204.7285 btu/hr, using the same 3.412142 factor as the rest of this chart.
Is this conversion exact or approximate?
The 3.412142 factor comes from a fixed, exact definitional constant, so the underlying math is exact; the numbers on this page are rounded to seven significant digits for readability, and the calculator above keeps the full-precision value.
Values are rounded to seven significant digits for display; the converter above uses the full-precision factor.
Reference: NIST Weights and Measures