Convert kWh to BTU kilowatt hours ↔ British thermal units Free Online Secure
Type a value in kilowatt hours and read it in British thermal units at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert kWh to BTU (kilowatt hours ↔ British thermal units)
| kWh | BTU |
|---|---|
| 1 | 3412.14163313 |
| 2 | 6824.28326626 |
| 3 | 10236.4248994 |
| 5 | 17060.7081656 |
| 10 | 34121.4163313 |
| 20 | 68242.8326626 |
| 50 | 170607.081656 |
| 100 | 341214.163313 |
Where these units come from
Energy collected a unit from every field that discovered it separately. The joule is the SI one and the plainest: a newton acting over a metre. The calorie came from the study of heat and was defined by warming water one degree — which is why there are several of them, depending on which degree you start from; the thermochemical calorie, exactly 4.184 J, is the one used here. The kilowatt hour is not a physicist's unit at all but an accountant's: a kilowatt drawn for an hour, which is how electricity is sold. The BTU is its British cousin, built from the pound and the Fahrenheit degree, and it still runs the heating and cooling trade worldwide.
Where you meet them
Joules belong to physics and to food labels outside the English-speaking world. Kilowatt hours arrive on every electricity bill and describe the capacity of batteries, from a phone to a car. BTUs rate air conditioners, boilers and gas appliances almost everywhere, including in countries that are otherwise entirely metric. Calories — in practice kilocalories — rule nutrition, which is the one place where the unit's name is routinely a thousand times out.
Questions people ask
Why is a kilowatt hour not just a kilowatt?
Because one is a rate and the other is an amount. A kilowatt is how fast energy flows — a kettle draws about two of them. A kilowatt hour is what you get if that flow continues for an hour, and it is what the meter counts and the bill charges for. Running a 2 kW kettle for six minutes uses 0.2 kWh; running a 10 W lamp all day uses about the same.
Which BTU does this page use?
The international-table BTU, exactly 1055.05585262 joules. Several others exist and differ in the fourth digit, so figures from different sources can disagree slightly. A BTU is roughly the heat needed to warm a pound of water by one degree Fahrenheit, and air conditioners are rated in BTU per hour: 12,000 of them is about 3.5 kilowatts.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Kilowatt-hours to BTU: reading an American heating bill
An American gas bill shows therms or hundreds of cubic feet, a furnace is rated in thousands of BTU per hour and a bag of wood pellets carries a heat value in BTU per pound. A reader who buys power by the kilowatt-hour, whether in Britain, Canada, Australia or continental Europe, has to translate all of these to see which fuel is cheaper. To convert kWh to BTU, multiply by 3,412: 1 kWh is 3,412 BTU, 29.3 kWh is one therm (100,000 BTU) and 293 kWh is one MMBtu (1,000,000 BTU). The calculator above multiplies as you type, and the sections below show how to read the heat content of fuels, boilers and heaters.
The page gives the rule with worked examples, a profile of each unit, a comparison and a long run of heating and fuel cases, followed by the usual mistakes. The calculation runs in your browser and nothing you type is sent anywhere. For sizing a heating system, rely on a qualified engineer.
How to convert kWh to BTU: multiply by 3,412
The rule
One BTU is 1,055 joules and one kWh is 3,600,000 joules, so one kWh contains 3,412.14 BTU. To convert kWh to BTU, multiply the kWh by 3,412: 0.5 kWh gives 1,706 BTU, 5 kWh gives 17,061 BTU and 100 kWh gives 341,214 BTU. To go back, multiply BTU by 0.000293.
Worked examples
An electric heater of 1.5 kW running for an hour supplies 5,118 BTU. A gas furnace rated at 80,000 BTU/h delivers 23.4 kW. A household that uses 10,500 kWh of electricity in a year has used 35.8 million BTU.
Why the factor stays
The factor follows from the definitions of the joule, the BTU and the kWh, so there is no rounding in it. Makers write 3,412 or 3,413, which differ by 0.01 per cent.
A quick sanity test
The answer in BTU is about 3,400 times the number of kWh. If a “convert kWh to BTU” calculation gave a smaller number than you started with, you divided instead of multiplying.
The kilowatt-hour
The unit of the electricity meter
The kilowatt-hour is how electricity is measured and sold. It is increasingly also used for gas, because many countries bill gas in kWh too. It is the common currency for comparing fuels.
Where it appears
Electricity and gas bills in many countries, appliance labels and battery ratings.
The BTU
The American unit of heat
The British Thermal Unit is the heat needed to raise one pound of water by one degree Fahrenheit, about 1,055 joules. In the United States it is the standard unit for furnaces, boilers, fuel contents and air conditioners.
Where it appears
American heating and cooling equipment, fuel tables and gas bills.
kWh against BTU
One kWh is 3,412 BTU, so the figure in BTU is nearly 3,400 times larger. 2 kWh is 6,824 BTU and 10 kWh is 34,121 BTU. They measure the same energy; only the scale differs.
The conversion is exact. The main trap is mixing BTU, an amount of energy, with BTU per hour, a rate.
Where the conversion shows up
Gas bills
An American gas bill counts in therms, one therm being 100,000 BTU, 29.3 kWh, or in CCF, a hundred cubic feet, about 1.037 therms, 30.4 kWh. A house using 70 MMBtu of gas a year uses 20,500 kWh. A “convert kWh to BTU” calculation lets a European compare this with their own meter reading.
Furnaces and boilers
A residential furnace is rated 60,000 to 120,000 BTU/h, which is 17.6 to 35.2 kW. Its efficiency, the AFUE, is typically 80 to 97 per cent. A furnace with an input of 80,000 BTU/h and 95 per cent efficiency delivers 76,000 BTU/h, 22.3 kW, of heat.
Wood, oil and propane
A cord of dry oak holds about 24 MMBtu, 7,030 kWh. A gallon of heating oil holds 138,500 BTU, 40.6 kWh. A gallon of propane holds 91,500 BTU, 26.8 kWh, and a ton of wood pellets about 16.5 MMBtu, 4,840 kWh.
CCF, MCF and therms
The units of gas volume are a source of confusion: 1 CCF is 100 cubic feet, 1 MCF is 1,000 cubic feet and each holds about 1,037 BTU per cubic foot. So 1 MCF is 1.037 MMBtu, 304 kWh. The therm is the heat unit of the bill, and the exact heat content changes slightly between regions.
Biogas and digesters
Biogas from a digester holds about 600 BTU per cubic foot, which is 21,200 BTU per cubic metre, 6.2 kWh. A farm digester making 1,000 cubic metres a day produces 6,200 kWh of heat, 21.2 MMBtu. Such figures help farmers compare biogas with natural gas at roughly 1,037 BTU per cubic foot.
Solar thermal collectors
A square metre of sunshine at midday delivers 1,000 W, 3,412 BTU/h. A solar thermal collector of 4 m² with 60 per cent efficiency yields 2.4 kW, 8,190 BTU/h. Over a bright day of six hours that is 14 kWh, 49,000 BTU, enough to heat 200 litres of water by 60 degrees.
Hydrogen
A kilogram of hydrogen holds about 113,500 BTU on a lower-heating-value basis, 33.3 kWh, and 134,000 BTU, 39.4 kWh, on a higher basis. A fuel-cell car using one kilogram per 100 miles consumes the equivalent of 1,135 BTU a mile, 0.33 kWh. Differences between the two bases explain many conflicting claims about efficiency.
A greenhouse
Heat loss from a greenhouse is the U-value times the area times the temperature difference. For 3,000 square feet of glazing with a U-value of 1.1 BTU/(h·ft²·°F) and a 40 °F difference, the loss is 132,000 BTU/h, 38.7 kW. Growers size boilers on this figure and pay for the kilowatt-hours.
Insulation and R-values
Heat loss through a wall is area times temperature difference divided by R. A wall of 1,000 square feet with R-19 insulation and a 40 °F difference loses 1,000 × 40 / 19 = 2,105 BTU/h, 0.62 kW. Doubling the R-value halves the loss, saving about 7.4 kWh a day if the difference persists.
The mental shortcut
To convert kWh to BTU in your head, multiply by 3.4 and add three zeros, then add 0.4 per cent. For 5 kWh: 17,000 plus 68 gives 17,068, against 17,061. For 2 kWh: 6,800 plus 27 gives 6,827, against 6,824. The error is tiny.
Spreadsheet formulas
To convert kWh to BTU in a spreadsheet, put the energies in kWh in column A and type =A2*3412.14 in column B. For the reverse, =B2/3412.14. A column with =A2*3.6 gives MJ for cross-checking.
Rounding and precision
Nameplate ratings are nominal, with tolerances of 5 to 10 per cent. When you convert kWh to BTU for a heater of 2.64 kW, rounding to 9,000 BTU/h is fine. More decimals do not make the appliance more exact.
Landmarks to memorise
0.1 kWh is 341 BTU. 1 kWh is 3,412 BTU. 3 kWh is 10,236 BTU. 10 kWh is 34,121 BTU. 29.3 kWh is 100,000 BTU. 100 kWh is 341,214 BTU. 293 kWh is one million BTU. Use them to convert kWh to BTU by eye.
Reference ladder
0.5 kWh is 1,706 BTU. 2 kWh is 6,824 BTU. 7 kWh is 23,885 BTU. 15 kWh is 51,182 BTU. 50 kWh is 170,607 BTU. 300 kWh is 1,023,643 BTU. 1,000 kWh is 3,412,142 BTU. A ladder like this makes checking easy.
Heating degree days
Engineers estimate fuel use with degree days. A house with a heat loss of 400 BTU/h per degree Fahrenheit that sees 5,000 degree days uses 400 × 24 × 5,000 = 48 MMBtu, 14,070 kWh, in a season. At 90 per cent efficiency the fuel needed is 53 MMBtu.
Checking by reversing
To check a “convert kWh to BTU” calculation result, multiply the answer by 0.000293. If 10 kWh became 34,121 BTU, then 34,121 times 0.000293 returns 10. A second test is size: the BTU number is about 3,400 times larger.
Link to MJ and kcal
One kWh is 3.6 MJ, 860 kcal and 3,412 BTU. One BTU is 1,055 J and 0.252 kcal. A heat of 10,000 BTU is 10.55 MJ, 2,520 kcal and 2.93 kWh. All three units describe the same heat.
A worked example
A homeowner compares a gas bill of 70 MMBtu a year with an electric heat pump. The gas heat at 92 per cent efficiency delivers 64.4 MMBtu, 18,870 kWh. A heat pump with a seasonal coefficient of 3.2 would need 5,900 kWh of electricity for the same heat. The conversion makes the comparison direct.
Baseboard heaters
A 6-foot electric baseboard heater of 1,500 W supplies 5,118 BTU/h. Three in a room give 15,350 BTU/h, 4.5 kW, enough for a room of 25 m² in a cold climate. They have no losses at the point of use, but they cost more than gas for the same heat.
Space heaters
A portable electric space heater of 1,500 W is the standard on many American circuits, as it fits a 15 A outlet at 120 V. It supplies 5,118 BTU/h. A kerosene heater of 20,000 BTU/h supplies 5.9 kW. Both are rated by their output in BTU/h.
Generators
A portable generator of 5 kW makes 5 kWh an hour, 17,060 BTU of electricity. It burns about 0.7 gallons of petrol an hour, 80,000 BTU, 23.4 kWh, so its efficiency is about 21 per cent. The numbers explain why generators are an expensive way to heat.
Two routes to one answer
You can go from kWh to BTU directly with 3,412.14, or via MJ: multiply by 3.6 and then by 947.8. If the results disagree, a digit was copied wrongly.
Engine heat and hot water on boats
A diesel engine of 100 kW rejects almost as much heat as it produces, roughly 100 kW, 341,000 BTU/h, to cooling water and exhaust. Boats use part of it for a hot-water tank. A tank of 20 gallons heated from 60 to 140 °F takes 20 × 8.34 × 80 = 13,360 BTU, 3.9 kWh, which the engine supplies in a few minutes.
Snow melting systems
A heated driveway needs 100 to 150 BTU/h per square foot to melt snow as it falls. For 600 square feet that is 60,000 to 90,000 BTU/h, 17.6 to 26.4 kW. Over a 10-hour storm the bill is 176 to 264 kWh, 600,000 to 900,000 BTU, which is why such systems run only when sensors detect snow.
Space heating in a garage or workshop
A two-car garage of 400 square feet with a fair standard of insulation loses about 20 BTU/h per square foot at a 40 °F difference, 8,000 BTU/h, 2.3 kW. A unit heater of 30,000 BTU/h, 8.8 kW, warms it up quickly, then cycles on and off. Over a cold day it may use 15 to 25 kWh, 51,000 to 85,000 BTU, of energy.
Hot tubs
A hot tub of 400 gallons heated by 40 °F takes 400 × 8.34 × 40 = 133,440 BTU, which is 39.1 kWh. A 4 kW electric heater needs about 10 hours for it, while a gas heater of 40,000 BTU/h needs just over 3 hours. Keeping the tub hot costs another 1 to 3 kWh a day, 3,400 to 10,200 BTU, depending on the cover.
Hot-water radiators and baseboards
Hydronic baseboard emits about 500 to 600 BTU/h per linear foot at an average water temperature of 180 °F, which is 146 to 176 W. A 10-foot run delivers 5,500 BTU/h, 1.6 kW. Lowering the water temperature to 140 °F cuts the output to about 60 per cent, a point worth noting before fitting a heat pump.
Heat pumps and HSPF
A heat pump's heating season performance factor, HSPF, is given in BTU of heat per watt-hour of electricity. An HSPF of 10 equals 10 BTU/Wh, which is a coefficient of 2.93. An HSPF of 13, popular for modern units, means 3.8. A “convert kWh to BTU” calculation on the electricity shows the heat delivered.
Water heaters
A gas water heater of 40,000 BTU/h delivers 11.7 kW of heat. To warm 50 gallons of water by 70 °F takes 50 × 8.34 × 70 = 29,190 BTU, 8.55 kWh. An electric heater with a 4.5 kW element takes about 2 hours to do the same, and a 40,000 BTU/h gas unit takes about 45 minutes.
Pool heating
Heating 20,000 gallons of pool water by 10 °F takes 20,000 × 8.34 × 10 = 1.67 MMBtu, 489 kWh. A gas pool heater of 250,000 BTU/h, 73 kW, does it in 6.7 hours at full output. A heat pump with a coefficient of 5 needs only about 100 kWh of electricity.
Ice making
Freezing a pound of water at 32 °F takes 144 BTU, so a ton of ice, 2,000 lb, takes 288,000 BTU, 84.4 kWh. An ice machine making a ton a day removes an average of 12,000 BTU/h, 3.5 kW, which is where the "ton of refrigeration" came from. A “convert kWh to BTU” calculation links the freezer's electricity to the cold it makes.
EER and SEER
The energy efficiency ratio is the BTU/h of cooling per watt of electricity. An EER of 12 equals 12 BTU per Wh, a coefficient of 3.5. The seasonal ratio, SEER, is a similar figure averaged over a season. A unit rated SEER 16 delivers 16 BTU of cooling for each watt-hour.
Fireplaces and stoves
A wood stove rated at 60,000 BTU/h gives 17.6 kW, and a gas log set of 30,000 BTU/h 8.8 kW. A pellet stove burns around 1 kg, 2.2 lb, per hour for 20,000 BTU/h, 5.9 kW. The ratings are maximum outputs and real use is a fraction of them.
More values for convert kWh to BTU
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 kWh = 341.214 BTU
- 0.5 kWh = 1,706.07 BTU
- 3 kWh = 10,236.4 BTU
- 4 kWh = 13,648.6 BTU
- 7 kWh = 23,885 BTU
- 15 kWh = 51,182.1 BTU
- 20 kWh = 68,242.8 BTU
- 75 kWh = 255,911 BTU
- 200 kWh = 682,428 BTU
- 500 kWh = 1,706,071 BTU
- 2,000 kWh = 6,824,283 BTU
- 10,000 kWh = 34,121,416 BTU
Common slips with a “convert kWh to BTU” calculation
Dividing by 3,412
From kWh to BTU the number grows. If 10 kWh became 0.003, you divided instead of multiplying.
BTU and BTU per hour
An air conditioner labelled "12,000 BTU" is rated at 12,000 BTU per hour, a power of 3.5 kW. In an hour it removes 3.5 kWh of heat. Read the rating carefully.
Cooling capacity and electricity
A rating of 12,000 BTU/h is the cooling output, not the electric input. The unit draws about 1 kW, not 3.5 kW. Confusing them leads to oversized wiring.
Short answers
How do I convert kWh to BTU?
Multiply the kWh by 3,412.
How many BTU is 1 kWh?
3,412.14 BTU.
How many BTU is 10 kWh?
34,121 BTU.
How many kWh is one BTU?
0.000293 kWh.
Does my number leave my device?
No, the calculation runs in your browser.
More pages and a wrap-up
For other energy conversions see Convert kWh to J, Convert kWh to cal, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C, Convert ha to m², Convert ft³ to L, Convert km/h to ft/s. The reverse direction is Convert BTU to kWh.
In short, a “convert kWh to BTU” calculation comes down to multiplying by 3,412 and writing the unit beside the answer. Your number is computed locally, with no account and no upload.