kWh to BTU Converter

One kilowatt-hour is 3,412 BTU — line up your electricity bill with air-conditioner and boiler ratings.

Conversion table

Energy	In BTU
0.5	1,706.06 BTU
1	3,412.13 BTU
1.5	5,118.19 BTU
2	6,824.26 BTU
2.5	8,530.32 BTU
3	10,236.38 BTU
4	13,648.51 BTU
5	17,060.64 BTU
6	20,472.77 BTU
7	23,884.9 BTU
8	27,297.03 BTU
9	30,709.15 BTU
10	34,121.28 BTU
12	40,945.54 BTU
15	51,181.92 BTU

🌡️ Energy landmarks

1 kWh3,412.14 BTU
1,000 BTU0.293 kWh
1 therm100,000 BTU = 29.3 kWh
1 ton of cooling12,000 BTU/h = 3.517 kW

Reading an appliance label

BTU on its own is energy; BTU/h is a rate. An air conditioner "of 12,000 BTU" always means 12,000 BTU per hour of cooling capacity.
Cooling capacity is not electricity used. A 12,000 BTU/h unit removes 3.5 kW of heat while drawing roughly 1.0–1.2 kW from the socket, because it moves heat rather than making cold.
One ton of refrigeration is 12,000 BTU/h, a leftover from the days when cooling was measured against melting ice.
Gas in the United States is billed in therms of 100,000 BTU; in much of Europe the same gas arrives billed in kWh, and 1 therm is 29.3 kWh.

Two units, one quantity

A kilowatt-hour is what a one-kilowatt load consumes in one hour: 3.6 million joules. A British thermal unit is the heat needed to raise one pound of water by one degree Fahrenheit, about 1,055 joules. They measure exactly the same physical quantity — energy — with rulers of very different sizes, so one kWh contains 3,412.14 BTU. The split is historical, not scientific: electricity metering grew up in the metric world of watts, while heating and refrigeration in the United States grew up around water, pounds and Fahrenheit, and exported that vocabulary with the equipment.

Why air conditioners are sold in BTU

An air conditioner is rated by how much heat it can move out of a room in an hour, and the American refrigeration industry has always expressed that in BTU per hour. The number describes capacity, not consumption: a 12,000 BTU/h unit shifts 3.517 kilowatts of heat while drawing perhaps 1.1 kilowatts of electricity, because a heat pump transports heat instead of producing cold. That ratio is what the efficiency ratings measure — EER and SEER are literally BTU per hour delivered for each watt drawn — and it is why a more efficient unit of the same BTU rating costs less to run without cooling any less.

From the rating to the bill

Find the watts, not the BTU. Divide the BTU/h capacity by the EER to get the electrical draw in watts.
A 12,000 BTU/h unit with an EER of 11 draws about 1,090 W, so eight hours a day is roughly 8.7 kWh.
At 0.20 per kWh, those eight hours cost about 1.74 a day and around 52 a month.
Oversizing costs money twice: a unit too large for the room short-cycles, which cools the air without removing humidity and wastes energy doing it.
Heating in BTU works the same way. A 24,000 BTU/h heat pump delivers about 7 kW of heat, but a resistive heater delivering 7 kW draws the full 7 kW.
Gas appliances are usually rated in BTU/h of input, not output; multiply by the efficiency to get the heat you actually receive.

Energy figures worth carrying around

1 kWh = 3,412 BTU = 3.6 MJ = 860 kcal.
A 100 W bulb left on for ten hours: 1 kWh, or 3,412 BTU.
A typical household uses 250–900 kWh a month depending on climate and heating type.
1 cubic metre of natural gas holds roughly 10.5 kWh, or about 35,800 BTU.
A litre of petrol holds about 9.5 kWh, some 32,400 BTU, though an engine wastes most of it as heat.
A 5 kWh home battery stores about 17,000 BTU, enough to run a 12,000 BTU/h air conditioner for roughly four hours.

Worked examples

From the meter to the appliance and back

One month of 300 kWh

300 kWh × 3,412.14 = 1,023,642 BTU
That is 10.2 therms of gas equivalent
Or 1,080 MJ

300 kWh = 1,023,642 BTU

Running a 12,000 BTU/h unit for 8 hours

Cooling delivered: 12,000 × 8 = 96,000 BTU
96,000 BTU ÷ 3,412.14 = 28.1 kWh of heat moved
At EER 11 the electricity used is about 8.7 kWh

28.1 kWh of cooling for 8.7 kWh of electricity

Frequently Asked Questions

How many BTU are in 1 kWh?

3,412.14 BTU. Both units measure energy: a kilowatt-hour is 3.6 million joules and one BTU is about 1,055 joules, so the ratio falls out of the definitions. Going the other way, 1,000 BTU is 0.293 kWh.

Is a 12,000 BTU air conditioner the same as 12,000 BTU of energy?

No, and this is the most expensive misreading on the label. Air conditioners are rated in BTU per hour, a rate of heat removal. A 12,000 BTU/h unit moves 12,000 BTU every hour it runs, which is 3.517 kW of cooling capacity — not a fixed amount of stored energy.

How much electricity does a 12,000 BTU air conditioner use?

Far less than 3.5 kW, because it moves heat rather than creating cold. Divide the capacity by the EER: at EER 11, 12,000 ÷ 11 gives about 1,090 watts. Eight hours a day is roughly 8.7 kWh, so the efficiency rating matters more to the bill than the BTU number does.

What is a ton of cooling?

12,000 BTU per hour, which is 3.517 kW. The name is literal: it is roughly the rate of cooling you would get from a ton of ice melting over 24 hours, a benchmark from the era when buildings were cooled with delivered ice. Residential units are commonly 1 to 5 tons.

How do I convert therms to kWh?

One therm is 100,000 BTU, which is 29.3 kWh. American gas bills use therms or ccf, while many European gas bills already arrive in kWh, so this is the conversion you need to compare a gas price with an electricity price on the same scale.

Why does heating use BTU while electricity uses kWh?

History rather than physics. Electric metering was built around the watt from the beginning, so the natural unit was the watt-hour. Heating and refrigeration grew out of American engineering practice measured in pounds of water and degrees Fahrenheit, and when that equipment was exported the unit went with it — which is why a shop in Madrid or São Paulo still sells air conditioners in BTU.