1 kWh in BTU
- Value
- 1 kWh
- From
- kilowatt-hour (kWh)
- To
- British thermal unit (BTU)
- Converted value
- 3,412.14163313 BTU
Checked against: 3,600,000 J ÷ 1055.05585262 J (International Table BTU, NIST SP 811 App. B)
Energy converter
Convert kWh to BTU, calories to joules, kcal to kJ and therms to kWh, using the exact definitions of the joule, calorie, BTU and electronvolt.
By AdminDrafted with AI writing toolsUpdated Checked examples: 4
Converted value
BTU
Converted value: 3,412.14163313 BTU
- Conversion
- 1 kWh ≈ 3,412.142 BTU
- Conversion factor
- 3,412.14163313
- Exactness
- Exact definitions, repeating decimal
1 kWh is about 3,412.142 BTU.
The same amount counted in each unit
1 kWh in every Energy unit
| Unit | Value | Definition |
|---|---|---|
| joule (J) | 3,600,000 | Base unit |
| kilojoule (kJ) | 3,600 | 1 kJ = 1,000 J, exact |
| megajoule (MJ) | 3.6 | 1 MJ = 1,000,000 J, exact |
| watt-hour (Wh) | 1,000 | 1 Wh = 3,600 J, exact |
| kilowatt-hour (kWh) | 1 | 1 kWh = 3,600,000 J, exact |
| megawatt-hour (MWh) | 0.001 | 1 MWh = 3,600,000,000 J, exact |
| calorie (cal) | 860,420.7 | 1 cal = 4.184 J, exact (Thermochemical calorie) |
| kilocalorie (kcal) | 860.4207 | 1 kcal = 4,184 J, exact |
| British thermal unit (BTU) | 3,412.142 | 1 BTU = 1,055.05585262 J, exact |
| therm (US) (thm) | 0.03412956 | 1 thm = 105,480,400 J, exact |
| electronvolt (eV) | 2.246943 × 10²⁵ | 1 eV = 1.602176634 × 10⁻¹⁹ J, exact |
| erg | 36,000,000,000,000 | 1 erg = 1 × 10⁻⁷ J, exact |
| foot-pound (ft·lbf) | 2,655,224 | 1 ft·lbf = 1.3558179483314004 J, exact |
| tonne of oil equivalent (toe) | 0.00008598452 | 1 toe = 41,868,000,000 J, exact |
How it's calculated S
Convert kilowatt-hour to joule
1 kWh = 3,600,000 J, exact
Convert joule to British thermal unit
1 BTU = 1,055.05585262 J, exact
Combined factor
Both units are defined exactly, but the converted value is a repeating decimal; it is shown to 12 significant figures.
About the energy converter
Every energy unit is a fixed number of joules. A kilowatt-hour is exactly 3.6 MJ (1,000 W for 3,600 s), the thermochemical calorie is 4.184 J, and the International Table British thermal unit is 1,055.05585262 J (NIST SP 811), so each factor is a definition rather than a measurement.
The default converts 1 kWh to 3,412.14 BTU, the link between electricity bills and heating or air-conditioning ratings. Food energy is the other everyday use: a food Calorie is a kilocalorie, so a 2,000 kcal day is 8,368 kJ.
Some units share a name but not a size. The International Table calorie (4.1868 J) is about 0.07% larger than the thermochemical one used here. The US therm (105,480,400 J) is the NIST therm convention used here. Temperature-specific BTU conventions, such as the 59 °F BTU, are distinct from the International Table BTU. Comparing the US therm with International Table BTU gives about 99,976 of those units rather than 100,000.
How to convert kWh to BTU
The shortened BTU coefficients and displayed converted decimals below are rounded approximations; full joule definitions remain exact.
Multiply kilowatt-hours by 3,412.14: 1 kWh = 3,412.14 BTU, because a kWh is exactly 3,600,000 J and an International Table BTU is 1,055.05585262 J. Use it to compare electricity with fuels whose energy is quoted in BTU, such as natural gas and heating oil.
To go from BTU to kWh, divide by 3,412.14 or multiply by 0.000293071: 100,000 BTU is 29.31 kWh. NIST SP 811, Appendix B.9 lists both units as exact joule values, so only the decimal rounding is approximate.
How to convert kcal to kJ
Multiply kilocalories by 4.184: a 250 kcal snack is 1,046 kJ, and a 2,000 kcal day is 8,368 kJ. Divide kJ by 4.184 to get kcal, so 1,000 kJ is 239.01 kcal.
The food Calorie with a capital C, printed on nutrition labels, is a kilocalorie. EU labels give energy in both kJ and kcal.
Calories to joules: which calorie?
The calorie in these conversions is the thermochemical one, exactly 4.184 J, so a kilocalorie is 4,184 J. The International Table calorie is 4.1868 J, about 0.07% larger: on that basis 250 kcal is 1,046.7 kJ.
kWh, joules and megajoules
A watt is one joule per second, so a watt-hour is 3,600 J and a kilowatt-hour is exactly 3.6 MJ. Electricity bills in the UK and India count "units", and one unit is 1 kWh.
A 2 kW heater running for 3 hours uses 6 kWh, which is 21.6 MJ or 20,473 BTU.
Therms, electronvolts and other units
- US therm: do not infer its exact factor merely from 100,000 BTU of the 59 °F kind; use the stated definition of 105,480,400 J. That is about 29.3001 kWh or about 99,976 International Table BTU.
- Comparison quantity, not an EC therm definition: 100,000 International Table BTU is 105,505,585.262 J or approximately 29.3071 kWh, about 0.024% more than the US therm. The converter offers the US therm only.
- Electronvolt: exactly 1.602176634 × 10⁻¹⁹ J, the energy one electron gains across one volt, fixed by the 2019 SI definition of the elementary charge.
- Foot-pound: 1 ft·lbf is 1.3558179483314004 J, so 1 J is 0.737562 ft·lbf.
- Erg: 10⁻⁷ J, the CGS unit.
- Tonne of oil equivalent: a statistical convention of 41.868 GJ (11,630 kWh), equal to 10 million International Table kilocalories, not the heat content of a particular oil.
Energy conversion chart
Repeating decimals are rounded to six places, and the eV row is in scientific notation.
| Value | From | To | Converted energy |
|---|---|---|---|
| 1 | kWh | BTU | 3412.141633 |
| 1 | kWh | MJ | 3.6 |
| 250 | kcal | kJ | 1046 |
| 1 | cal | J | 4.184 |
| 1 | eV | J | 1.602176634e-19 |
| 1 | thm | kWh | 29.300111 |
Energy vs power
kWh, BTU and calories measure an amount of energy; kW and BTU/h measure a rate. Multiply a rate by time to get energy: a 3 kW kettle running for 4 minutes uses 3 × 4/60 = 0.2 kWh.
Ratings in watts, horsepower or BTU/h belong in the power converter.
Common mistakes
- Choosing cal for a food Calorie. The result comes out 1,000 times too small: 250 Cal is 1,046 kJ, not 1.046 kJ.
- Reading a "12,000 BTU" air conditioner as an amount of energy. The rating means 12,000 BTU per hour, a power of 3.517 kW.
- Writing kW for kWh. A kW rating gives no energy until you know how long the device ran.
- Mixing therm or calorie definitions. The two energy comparison quantities above differ by about 0.024% and the two calories by 0.07%, so check which one a gas contract or lab source uses.
Related energy tools
For food energy in one direction, use kcal to kJ or kJ to kcal. The electricity cost calculator turns appliance watts and hours into kWh and cost, and the specific heat calculator finds the energy needed to heat a mass with Q = mcΔT.
Worked examples
1 kcal in kJ
- Value
- 1 kcal
- From
- kilocalorie (kcal)
- To
- kilojoule (kJ)
- Converted value
- 4.184 kJ
- Exactness
- Exact
Checked against: Thermochemical calorie = 4.184 J exactly (NIST SP 811 App. B)
1 eV in joules
- Value
- 1 eV
- From
- electronvolt (eV)
- To
- joule (J)
- Converted value
- 1.602176634 × 10⁻¹⁹ J
Checked against: e = 1.602176634 × 10⁻¹⁹ C exactly (SI 2019), so 1 eV = 1.602176634 × 10⁻¹⁹ J
1 US therm in BTU
- Value
- 1 thm
- From
- therm (US) (thm)
- To
- British thermal unit (BTU)
- Converted value
- 99,976.1289775 BTU
Checked against: 105,480,400 J (NIST SP 811 App. B) ÷ 1055.05585262 J
Questions
How many BTU are in a kWh?
3,412.14 BTU. A kWh is 3,600,000 J and the International Table BTU is 1,055.05585262 J, so 3,600,000 ÷ 1,055.05585262 ≈ 3,412.1416. In the other direction 1 BTU is 0.000293071 kWh, so 100,000 BTU of heat is 29.31 kWh.
How many joules are in a calorie?
4.184 J for the thermochemical calorie used here, or 4.1868 J for the International Table calorie; NIST SP 811 lists both. Nutrition labels count kilocalories, often printed as “Calories”, so one food Calorie is 4,184 J or 4.184 kJ. EU food labels give energy in both kJ and kcal.
What is a unit of electricity?
One kilowatt-hour, 3.6 MJ: the energy a 1,000 W appliance uses in one hour. Electricity bills in the UK and India count “units” in kWh, so a 2 kW heater running for 3 hours uses 6 units, and a 10 W LED bulb takes 100 hours to use one.
What is the difference between kW and kWh?
A kilowatt measures power, the rate at which energy is used; a kilowatt-hour measures the energy itself, power multiplied by time. A 3 kW kettle running for 4 minutes uses 3 × 4/60 = 0.2 kWh. Convert kW with the power converter and kWh with this one.
How many kWh are in a therm?
About 29.3 kWh. The US therm is 105,480,400 J (NIST SP 811), or approximately 29.3001 kWh. As a separately named comparison quantity, 100,000 International Table BTU is exactly 105,505,585.262 J, or approximately 29.3071 kWh. These energy quantities differ by about 0.024%, so each rounds here to 29.3 kWh. The converter’s therm unit is the US therm.
About this calculator
Sources
Checked against references
This calculator includes 4 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.