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Convert joules to kwh

1 joule equals 2.7777778e-7 kilowatt-hours. Enter a value below to convert instantly.

Joules to kilowatt-hours turns a physics or engineering energy figure into billing terms. Divide by 3,600,000. The joule is inconveniently small for domestic energy — a single kettle boil is over a million joules — which is exactly why the kilowatt-hour exists.

1 J
2.7777778e-7 kWh

Multiply the number of joules by 2.7777777777777776e-7 to get kilowatt-hours. How this is calculated

Copy link puts your number after the #, which browsers never send to a server — but the link itself carries it, so anyone you send it to sees the value. Save keeps the unit pair in this browser only; clear it any time from your saved list.

Need the other direction? Convert kilowatt-hour to joule →

Formula

Multiply the number of joules by 2.7777777777777776e-7 to get kilowatt-hours.

Step by step

  1. Start with 1 J.
  2. Multiply by the conversion factor 2.7777777777777776e-7.
  3. 1 × 2.7777777777777776e-7 = 2.7777778e-7 kWh.

Joules to Kilowatt-hours conversion table

Joules (J) Kilowatt-hours (kWh)
1 2.7777778e-7
2 5.5555556e-7
5 0.0000013888889
10 0.0000027777778
20 0.0000055555556
50 0.000013888889
100 0.000027777778
500 0.00013888889
1,000 0.00027777778

Where joules and kilowatt-hours are used together

Reading an electricity bill

Meters count kilowatt-hours. A 2 kW heater run for three hours uses 6 kWh, which is 21.6 MJ. Tariffs are per kWh, so this is the unit that turns physics into money.

Battery and EV capacity

EV batteries are rated in kWh — a 60 kWh pack holds 216 MJ. Consumption is quoted in kWh per 100 km, which makes efficiency comparisons straightforward within the unit and awkward against a fuel figure in litres.

Solar generation

Panel output is a power rating in watts; generation over a day is energy in kilowatt-hours. A 5 kW array producing for the equivalent of four full-sun hours yields about 20 kWh, or 72 MJ.

Comparing energy sources

Gas is billed in kWh or therms, food energy is in kilocalories, and physics works in joules. Converting everything to joules is the only way to compare them on a common basis.

Everyday joules worth knowing

Values people actually look up, with the reason each one comes up. Every figure is calculated with the same engine as the converter above.

Joule (J) Kilowatt-hour (kWh) What it is
1,000,000 0.27777778 One megajoule
3,600,000 1 Exactly one kilowatt-hour
10,000,000 2.7777778 Ten megajoules
100,000,000 27.777778 One hundred megajoules
105,500,000 29.305556 About one therm of gas
216,000,000 60 A 60 kWh EV battery
1,000,000,000 277.77778 One gigajoule
3,600,000,000 1,000 One megawatt-hour

How these two units are defined

The joule is the SI unit of energy: one watt for one second, or one newton acting through one metre. The kilowatt-hour is not an SI unit but is a legitimate composite of SI units, defined as exactly 3.6 MJ. Utilities use it because domestic consumption in joules would run to hundreds of millions. Note the difference between power and energy: a kilowatt is a rate, a kilowatt-hour is an amount. Confusing them is the single most common error in energy arithmetic.

Rounding and precision

The 3.6 MJ definition is exact, so no precision is lost. Meter readings are typically resolved to 0.1 kWh, and energy figures on appliance labels are test-standard values with their own tolerance. When converting to joules the number grows by six orders of magnitude, which makes it easy to present far more significant figures than the input justified — round back to the precision of the original reading.

Mistakes people make with this conversion

  • Confusing kW with kWh

    A kilowatt is a rate; a kilowatt-hour is an amount of energy. 'A 5 kW battery' is meaningless — batteries store kWh and deliver kW.

  • Multiplying by 3,600 instead of 3,600,000

    That converts kilowatt-hours to kilojoules, not joules. The factor from kWh to J is 3.6 million.

  • Mixing up calories and kilocalories

    Food 'calories' are kilocalories. One kcal is 4,184 J, so a 2,000 kcal daily intake is about 8.4 MJ, or 2.3 kWh.

Read more about these units

Sources for this page

  1. SI Brochure — The International System of Units (SI), 9th edition BIPM (Bureau International des Poids et Mesures) · Definitions of the SI base and derived units, and the SI prefixes.
  2. Special Publication 811 — Guide for the Use of the International System of Units (SI) NIST (US National Institute of Standards and Technology) · Conversion factors between US customary and SI units, and the rounding and significant-figure conventions this site follows.

Content on this page last reviewed 12 August 2026. Spotted an error? Report it — see also how these values are calculated.

Convert Joule to other energy units

1 J expressed in every other energy unit on this site.

  • Kilojoule kJ 0.001
  • Megajoule MJ 0.000001
  • Gigajoule GJ 1e-9
  • Millijoule mJ 1,000
  • Microjoule µJ 1,000,000
  • Nanojoule nJ 1,000,000,000
  • Attojoule aJ 1e+18
  • Erg erg 10,000,000
  • Calorie (thermochemical) cal 0.23900574
  • Kilocalorie kcal 0.00023900574
  • Calorie (IT) cal(IT) 0.2388459
  • Kilocalorie (IT) kcal(IT) 0.0002388459
  • Megacalorie Mcal 2.3900574e-7
  • Watt-hour Wh 0.00027777778
  • Kilowatt-hour kWh 2.7777778e-7
  • Megawatt-hour MWh 2.7777778e-10
  • Gigawatt-hour GWh 2.7777778e-13
  • Watt-second W·s 1
  • Kilowatt-second kW·s 0.001
  • Horsepower-hour hp·h 3.7250614e-7
  • British Thermal Unit BTU 0.00094781712
  • BTU (thermochemical) BTU(th) 0.00094845141
  • MBTU (thousand BTU) MBTU 9.4781712e-7
  • MMBTU (million BTU) MMBTU 9.4781712e-10
  • Therm (US) thm (US) 9.4804343e-9
  • Therm (EC) thm (EC) 9.4781339e-9
  • Ton-hour (refrigeration) ton·h 7.8984761e-8
  • Foot-pound ft·lbf 0.73756215
  • Inch-pound in·lbf 8.8507458
  • Foot-poundal ft·pdl 23.73036
  • Kilogram-force Meter kgf·m 0.10197162
  • Gram-force Centimeter gf·cm 10,197.162
  • Gram-force Meter gf·m 101.97162
  • Kilogram-force Centimeter kgf·cm 10.197162
  • Ounce-force Inch ozf·in 141.61193
  • Horsepower-hour (metric) PS·h 3.7767267e-7
  • Electronvolt eV 6.2415091e+18
  • Kiloelectronvolt keV 6.2415091e+15
  • Megaelectronvolt MeV 6,241,509,100,000
  • Gigaelectronvolt GeV 6,241,509,100
  • Hartree Eh 2.2937123e+17
  • Rydberg Ry 4.5874246e+17
  • Ton of TNT tTNT 2.3900574e-10
  • Kiloton of TNT ktTNT 2.3900574e-13
  • Megaton of TNT MtTNT 2.3900574e-16
  • Tonne of Oil Equivalent toe 2.388459e-11
  • Barrel of Oil Equivalent bboe 1.6345576e-10
  • Gigaton of TNT GtTNT 2.3900574e-19
  • Fuel Oil Equivalent (kiloliter) FOE (kL) 2.487709e-11
  • Fuel Oil Equivalent (US barrel) FOE (bbl) 1.5666399e-10

About the joule

The joule (J) is a SI unit of energy.

About the kilowatt-hour

The kilowatt-hour (kWh) is a Metric unit of energy. The billing unit on electricity meters — one kilowatt drawn for one hour.

Related conversions

Frequently asked questions

How many kilowatt-hours is a megajoule?

One MJ is 0.2778 kWh. Going the other way, a kilowatt-hour is 3.6 MJ.

How do I convert joules to my electricity bill?

Divide the joules by 3,600,000 to get kilowatt-hours, then multiply by the tariff rate per kWh. Standing charges and tiered rates are separate from the energy arithmetic.

Is a watt-second the same as a joule?

Yes, exactly. A watt is a joule per second, so a watt-second is a joule. Camera flash energy is often quoted in watt-seconds for this reason.

How many kilowatt-hours are in a joule?

One joule equals 2.7777778e-7 kilowatt-hours.

How do you convert joules to kilowatt-hours?

Multiply the number of joules by 2.7777777777777776e-7 to get kilowatt-hours.

What is 1 kilowatt-hour in joules?

One kilowatt-hour equals 3,600,000 joules.

When would I convert joules to kilowatt-hours?

This conversion is common when nutrition labels, electricity bills, heating, and physics.