Kilojoules (kJ)
The kilojoule is 1,000 joules. It is the unit of food energy on labels in Australia, New Zealand and the EU (alongside kcal), and a common unit in chemistry.
Convert kilojoules to any energy unit
1 kilojoule = 1,000 joules
Quick facts
- Unit
- Kilojoule (plural: kilojoules)
- Symbol
- kJ
- Measures
- Energy / Work / Heat
- System
- Metric (SI)
- Equals
- 1,000 joules
- Definition
- 1,000 joules.
- Also written
- kilojoules
1 kilojoule in other units
| Joules | 1,000 J |
| Kilocalories | 0.2390057361 kcal |
| Kilowatt-hours | 0.000277777778 kWh |
| British thermal units | 0.9478171203 BTU |
| Calories | 239.0057361 cal |
| Calories (food) | 0.2390057361 Cal |
| Electronvolts | 6.2415091 × 1021 eV |
| Watt-hours | 0.2777777778 Wh |
What is a kilojoule?
The kilojoule is 1,000 joules. It is the unit of food energy on labels in Australia, New Zealand and the EU (alongside kcal), and a common unit in chemistry. One kilocalorie is 4.184 kJ.
Where the kilojoule sits among energy units
The kilojoule is number 35 of 99 on our scale of energy units, ordered from smallest to largest.
What kilojoules are used for
- Food labels in Australia, New Zealand and Europe
- Chemistry: reaction energies in kJ/mol
- Exercise machines and fitness trackers
Kilojoules in real life
- An apple contains about 400 kJ
- Adults need about 8,700 kJ of food energy a day
- A slice of bread is about 300 kJ
One kilojoule is about 24% of the energy in a food Calorie, or about 10% of the energy in an AA battery, or about the energy of 1,000 apple lifts.
Top kilojoule conversions
- Kilojoules to joules
- Kilojoules to kilocalories
- Kilojoules to kilowatt-hours
- Kilojoules to British thermal units
- Kilojoules to calories
- Kilojoules to Calories (food)
- Kilojoules to electronvolts
- Kilojoules to watt-hours
- Kilojoules to foot-pounds
- Kilojoules to megajoules
- Kilojoules to therms
- Kilojoules to megawatt-hours
Common amounts of kilojoules
- 0.1 kJ
- 0.2 kJ
- 0.3 kJ
- 0.4 kJ
- 0.5 kJ
- 0.6 kJ
- 0.7 kJ
- 0.8 kJ
- 0.9 kJ
- 1 kJ
- 1.5 kJ
- 2 kJ
- 2.5 kJ
- 3 kJ
- 3.5 kJ
- 4 kJ
- 4.5 kJ
- 5 kJ
- 6 kJ
- 7 kJ
- 7.5 kJ
- 8 kJ
- 9 kJ
- 10 kJ
- 11 kJ
- 12 kJ
- 13 kJ
- 14 kJ
- 15 kJ
- 16 kJ
- 17 kJ
- 18 kJ
- 19 kJ
- 20 kJ
- 21 kJ
- 22 kJ
- 23 kJ
- 24 kJ
- 25 kJ
- 26 kJ
- 27 kJ
- 28 kJ
- 29 kJ
- 30 kJ
- 31 kJ
- 32 kJ
- 33 kJ
- 34 kJ
- 35 kJ
- 36 kJ
- 37 kJ
- 38 kJ
- 39 kJ
- 40 kJ
- 41 kJ
- 42 kJ
- 43 kJ
- 44 kJ
- 45 kJ
- 46 kJ
- 47 kJ
- 48 kJ
- 49 kJ
- 50 kJ
- 51 kJ
- 52 kJ
- 53 kJ
- 54 kJ
- 55 kJ
- 56 kJ
- 57 kJ
- 58 kJ
- 59 kJ
- 60 kJ
- 61 kJ
- 62 kJ
- 63 kJ
- 64 kJ
- 65 kJ
- 66 kJ
- 67 kJ
- 68 kJ
- 69 kJ
- 70 kJ
- 71 kJ
- 72 kJ
- 73 kJ
- 74 kJ
- 75 kJ
- 76 kJ
- 77 kJ
- 78 kJ
- 79 kJ
- 80 kJ
- 81 kJ
- 82 kJ
- 83 kJ
- 84 kJ
- 85 kJ
- 86 kJ
- 87 kJ
- 88 kJ
- 89 kJ
- 90 kJ
- 91 kJ
- 92 kJ
- 93 kJ
- 94 kJ
- 95 kJ
- 96 kJ
- 97 kJ
- 98 kJ
- 99 kJ
- 100 kJ
- 110 kJ
- 120 kJ
- 130 kJ
- 140 kJ
- 150 kJ
- 160 kJ
- 170 kJ
- 180 kJ
- 190 kJ
- 200 kJ
- 210 kJ
- 220 kJ
- 230 kJ
- 240 kJ
- 250 kJ
- 260 kJ
- 270 kJ
- 280 kJ
- 290 kJ
- 300 kJ
- 310 kJ
- 320 kJ
- 330 kJ
- 340 kJ
- 350 kJ
- 360 kJ
- 370 kJ
- 380 kJ
- 390 kJ
- 400 kJ
- 410 kJ
- 420 kJ
- 430 kJ
- 440 kJ
- 450 kJ
- 460 kJ
- 470 kJ
- 480 kJ
- 490 kJ
- 500 kJ
- 600 kJ
- 700 kJ
- 800 kJ
- 900 kJ
- 1,000 kJ
- 1,200 kJ
- 1,500 kJ
- 2,000 kJ
- 2,500 kJ
- 3,000 kJ
- 4,000 kJ
- 5,000 kJ
- 10,000 kJ
Convert kilojoules to all 98 other units
Metric (SI)
Electrical
Calories
- kJ to kcal
- kJ to cal
- kJ to Cal
- kJ to cal_IT
- kJ to Gcal
- kJ to Mcal
- kJ to cal₁₅
- kJ to th
- kJ to cal₂₀
- kJ to cal_mean
BTU & therms
- kJ to BTU
- kJ to thm
- kJ to MMBtu
- kJ to MBtu
- kJ to Dth
- kJ to quad
- kJ to thm (EC)
- kJ to BTU_th
- kJ to BTU₅₉
- kJ to CHU
- kJ to Q
- kJ to BTU₃₉
- kJ to BTU₆₀
- kJ to BTU_mean
Mechanical
- kJ to ft⋅lbf
- kJ to erg
- kJ to in⋅lbf
- kJ to hp⋅h
- kJ to L⋅atm
- kJ to kgf⋅m
- kJ to ft⋅pdl
- kJ to in⋅ozf
- kJ to PS⋅h
- kJ to cm³⋅atm
- kJ to ft³⋅atm
- kJ to ft³⋅psi
Atomic & physics
- kJ to eV
- kJ to MeV
- kJ to GeV
- kJ to keV
- kJ to TeV
- kJ to Eh
- kJ to kJ/mol
- kJ to kcal/mol
- kJ to meV
- kJ to cm⁻¹
- kJ to EP
- kJ to PeV
- kJ to Ry
- kJ to EeV
- kJ to K·k_B
- kJ to foe
- kJ to h·Hz
Fuel & explosive equivalents
- kJ to BOE
- kJ to t TNT
- kJ to toe
- kJ to kt
- kJ to Mt
- kJ to cubic foot of natural gas
- kJ to GGE
- kJ to Mtoe
- kJ to cubic meter of natural gas
- kJ to tce
- kJ to ktoe
- kJ to liter of gasoline
- kJ to Gt
- kJ to g TNT
- kJ to kg TNT
- kJ to MMBOE
- kJ to kBOE
- kJ to DGE
Everyday comparisons
Convert to kilojoules
- Joules to kilojoules
- Kilocalories to kilojoules
- Kilowatt-hours to kilojoules
- British thermal units to kilojoules
- Calories to kilojoules
- Calories (food) to kilojoules
- Electronvolts to kilojoules
- Watt-hours to kilojoules
- Foot-pounds to kilojoules
- Megajoules to kilojoules
- Therms to kilojoules
- Megawatt-hours to kilojoules
Frequently asked questions
What is a kilojoule?
The kilojoule is 1,000 joules. It is the unit of food energy on labels in Australia, New Zealand and the EU (alongside kcal), and a common unit in chemistry.
How is the kilojoule defined?
1,000 joules.
How many joules are in a kilojoule?
One kilojoule equals 1,000 joules.
How many kilocalories are in a kilojoule?
One kilojoule equals 0.2390057361 kilocalories.
How many kilowatt-hours are in a kilojoule?
One kilojoule equals 0.000277777778 kilowatt-hours.