BTU to kW Conversion Calculator
Type a value in BTU/h, kW, tons or watts to see it in every other unit, with the conversion factor.
How to use the BTU to kW converter
- Open the Convert drop-down. Choose Power (BTU/h, kW, tons…) for cooling and heating ratings. Choose Energy (BTU, kWh, therm…) for totals such as energy use.
- Type the number into Value to convert. The help text under the field says the result lists every other unit.
- Pick the unit your number is in from From unit. For power, the options are BTU/h, kW, W, ton (refrigeration), MBH (1,000 BTU/h), hp (mechanical) and kcal/h. For energy, they are BTU, kWh, Wh, J, MJ, therm and kcal. This field appears only in some modes.
- Read the result rows. Only the rows that apply to your chosen mode are shown. In power mode, you will see BTU per hour, Kilowatts, Watts, Tons of refrigeration, MBH, Horsepower and Kilocalories per hour.
- Open How it was calculated below the result to see the formula and each step worked out with your numbers.
The example buttons above the form fill in 12,000 BTU/h, 3.5 kW, 2 tons, and 1 kWh → BTU, so you can see how a conversion works before entering your own figures. Reset returns the form to the starting example. Copy result copies the result lines with a link, and Copy link stores every input in the page address, so the same calculation reopens later. Print / save as PDF produces the inputs, results, steps and date on one page.
How do you convert BTU to kW?
Power conversion uses one fixed factor: 1 BTU/h equals 0.00029307 kW. To convert BTU per hour to kilowatts, divide by 3,412.14. To convert kilowatts to BTU per hour, multiply by 3,412.14. For example, 12,000 BTU/h ÷ 3,412.14 = 3.517 kW.
The factor comes from the definitions. This tool uses the international table BTU, which equals 1,055.05585262 joules. A watt is one joule per second, and an hour has 3,600 seconds, so 1 BTU/h = 1,055.05585262 ÷ 3,600 = 0.29307 W, or 0.00029307 kW. Other common conversions follow the same pattern:
- 1 ton of refrigeration = 12,000 BTU/h = 3.5169 kW
- 1 MBH = 1,000 BTU/h
- 1 hp = 745.7 W = 2,544 BTU/h
- 2 tons = 24,000 BTU/h = 7.034 kW
- 48 MBH = 48,000 BTU/h = 14.07 kW
Is BTU the same as BTU per hour?
No. BTU measures energy, while BTU/h measures power, which is energy per unit of time. Energy converts to kWh, and 1 kWh = 3,412.14 BTU. Power converts to kW. A “BTU” rating on an air conditioner or furnace almost always means BTU/h, the rate at which the unit moves heat. A 12,000 BTU/h air conditioner does not contain 12,000 BTU of energy. Natural gas bills use a related energy unit, the therm: 1 therm = 100,000 BTU = 29.31 kWh.
Common air conditioner and heater sizes in kW
The table under the result lists twelve common ratings from 5,000 to 60,000 BTU/h with their kW and tons, calculated with the same factor. A few of them: 5,000 BTU/h = 1.465 kW (0.42 ton); 9,000 BTU/h = 2.638 kW (0.75 ton); 18,000 BTU/h = 5.275 kW (1.5 tons); 24,000 BTU/h = 7.034 kW (2 tons); 36,000 BTU/h = 10.55 kW (3 tons); 60,000 BTU/h = 17.58 kW (5 tons). Metric equipment is usually rated in kW, so a 3.5 kW split unit sits just below a 12,000 BTU/h unit. When you compare a European or Asian catalogue with a US one, convert the rated capacity, not the electrical input: a 3.5 kW cooling rating and a 12,000 BTU/h rating describe heat moved, while the power the unit draws is listed separately on its label.
Sources
Data and methods used by this calculator (checked October 2026):
Worked examples
| Input | Result |
|---|---|
| 12000 BTU/h | 3.517 kW = 1 ton |
| 3.5 kW | 11,940 BTU/h = 0.9952 ton |
| 2 ton | 24,000 BTU/h = 7.034 kW |
| 48 MBH | 48,000 BTU/h = 14.07 kW |
| 1 kWh | 3,412 BTU = 0.03412 therm |
Calculated by the tool above with these values.
Frequently asked questions
How do I convert BTU to watts?
Enter the value in BTU/h and read the Watts row. The factor is 1 BTU/h = 0.29307 W (the same as 0.00029307 kW), so 12,000 BTU/h is 3,517 W, or 3.517 kW. A plain BTU is an amount of energy, not a rate, so use the BTU to kWh answer below for that.
How many BTU is 1 kW?
1 kW equals 3,412.14 BTU/h. This is a power figure, so use it for heating and cooling rates, not for total energy.
How many BTU in a ton?
One ton of refrigeration equals 12,000 BTU/h. That is 3.5169 kW. The term comes from the cooling capacity of melting one ton of ice in 24 hours.
How many kW is a 12,000 BTU air conditioner?
A 12,000 BTU/h air conditioner has 3.52 kW of cooling capacity. Its electrical input is lower, found by dividing the cooling capacity by the unit’s efficiency, which is listed on its label or spec sheet.
Does kW to BTU work the same way?
Yes, multiply kW by 3,412.14 to get BTU/h. For example, 3.5 kW × 3,412.14 = 11,940 BTU/h, which is 0.9952 ton.
How do I convert BTU to kWh?
Choose Energy in the Convert drop-down. 1 kWh = 3,412.14 BTU, so divide BTU by 3,412.14: 100,000 BTU (one therm) is 29.31 kWh. Use kWh and therms for energy totals on bills, and kW for equipment ratings.
How many BTU/h is 1 horsepower?
One mechanical horsepower is 745.7 W, which is about 2,544 BTU/h. The converter lists hp beside the other power units, but note that motor horsepower is the shaft output, not a cooling capacity.
Can I use the results on a quote or report?
Yes. Results may be used freely in commercial work such as quotes, proposals, reports and service records, with no attribution needed. For estimation only, verify critical designs against the applicable standard.
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