Joules (J)
The joule is the SI unit of energy, work and heat.
Convert joules to any energy unit
1 joule = 0.000239005736 kilocalories
Quick facts
- Unit
- Joule (plural: joules)
- Symbol
- J
- Measures
- Energy / Work / Heat
- System
- Metric (SI)
- Definition
- The work done by a force of one newton over one meter: 1 kg·m²/s².
- Also written
- newton-meter (energy), watt-second, Ws
1 joule in other units
| Kilocalories | 0.000239005736 kcal |
| Kilowatt-hours | 2.7777778 × 10-7 kWh |
| British thermal units | 0.00094781712 BTU |
| Calories | 0.2390057361 cal |
| Kilojoules | 0.001 kJ |
| Calories (food) | 0.000239005736 Cal |
| Electronvolts | 6.2415091 × 1018 eV |
| Watt-hours | 0.000277777778 Wh |
What is a joule?
The joule is the SI unit of energy, work and heat. One joule is the work done when a force of one newton moves an object one meter, or the energy used by a one-watt device in one second. It is named after the English physicist James Prescott Joule, who showed in the 1840s that heat and mechanical work are forms of the same thing.
A joule is small in everyday terms: lifting a medium apple one meter takes about 1 J, and a single food Calorie is 4,184 J.
Where the joule sits among energy units
The joule is number 24 of 99 on our scale of energy units, ordered from smallest to largest.
What joules are used for
- Physics and engineering calculations
- Food energy on EU and Australian labels (kJ)
- Energy of lasers, capacitors and defibrillators
- Heat in chemistry (kJ/mol)
Joules in real life
- Lifting a 100 g apple 1 m uses about 1 J
- A defibrillator shock is about 150–360 J
- A 60 W bulb uses 60 J every second
- Boiling a cup of water from 20 °C takes about 80,000 J
One joule is about the energy of lifting an apple one meter.
Top joule conversions
Common amounts of joules
- 0.1 J
- 0.2 J
- 0.3 J
- 0.4 J
- 0.5 J
- 0.6 J
- 0.7 J
- 0.8 J
- 0.9 J
- 1 J
- 1.5 J
- 2 J
- 2.5 J
- 3 J
- 3.5 J
- 4 J
- 4.5 J
- 5 J
- 6 J
- 7 J
- 7.5 J
- 8 J
- 9 J
- 10 J
- 11 J
- 12 J
- 13 J
- 14 J
- 15 J
- 16 J
- 17 J
- 18 J
- 19 J
- 20 J
- 21 J
- 22 J
- 23 J
- 24 J
- 25 J
- 26 J
- 27 J
- 28 J
- 29 J
- 30 J
- 31 J
- 32 J
- 33 J
- 34 J
- 35 J
- 36 J
- 37 J
- 38 J
- 39 J
- 40 J
- 41 J
- 42 J
- 43 J
- 44 J
- 45 J
- 46 J
- 47 J
- 48 J
- 49 J
- 50 J
- 51 J
- 52 J
- 53 J
- 54 J
- 55 J
- 56 J
- 57 J
- 58 J
- 59 J
- 60 J
- 61 J
- 62 J
- 63 J
- 64 J
- 65 J
- 66 J
- 67 J
- 68 J
- 69 J
- 70 J
- 71 J
- 72 J
- 73 J
- 74 J
- 75 J
- 76 J
- 77 J
- 78 J
- 79 J
- 80 J
- 81 J
- 82 J
- 83 J
- 84 J
- 85 J
- 86 J
- 87 J
- 88 J
- 89 J
- 90 J
- 91 J
- 92 J
- 93 J
- 94 J
- 95 J
- 96 J
- 97 J
- 98 J
- 99 J
- 100 J
- 110 J
- 120 J
- 130 J
- 140 J
- 150 J
- 160 J
- 170 J
- 180 J
- 190 J
- 200 J
- 210 J
- 220 J
- 230 J
- 240 J
- 250 J
- 260 J
- 270 J
- 280 J
- 290 J
- 300 J
- 310 J
- 320 J
- 330 J
- 340 J
- 350 J
- 360 J
- 370 J
- 380 J
- 390 J
- 400 J
- 410 J
- 420 J
- 430 J
- 440 J
- 450 J
- 460 J
- 470 J
- 480 J
- 490 J
- 500 J
- 600 J
- 700 J
- 800 J
- 900 J
- 1,000 J
- 1,200 J
- 1,500 J
- 2,000 J
- 2,500 J
- 3,000 J
- 4,000 J
- 5,000 J
- 10,000 J
Convert joules to all 98 other units
Metric (SI)
Electrical
Calories
BTU & therms
- J to BTU
- J to thm
- J to MMBtu
- J to MBtu
- J to Dth
- J to quad
- J to thm (EC)
- J to BTU_th
- J to BTU₅₉
- J to CHU
- J to Q
- J to BTU₃₉
- J to BTU₆₀
- J to BTU_mean
Mechanical
- J to ft⋅lbf
- J to erg
- J to in⋅lbf
- J to hp⋅h
- J to L⋅atm
- J to kgf⋅m
- J to ft⋅pdl
- J to in⋅ozf
- J to PS⋅h
- J to cm³⋅atm
- J to ft³⋅atm
- J to ft³⋅psi
Atomic & physics
- J to eV
- J to MeV
- J to GeV
- J to keV
- J to TeV
- J to Eh
- J to kJ/mol
- J to kcal/mol
- J to meV
- J to cm⁻¹
- J to EP
- J to PeV
- J to Ry
- J to EeV
- J to K·k_B
- J to foe
- J to h·Hz
Fuel & explosive equivalents
- J to BOE
- J to t TNT
- J to toe
- J to kt
- J to Mt
- J to cubic foot of natural gas
- J to GGE
- J to Mtoe
- J to cubic meter of natural gas
- J to tce
- J to ktoe
- J to liter of gasoline
- J to Gt
- J to g TNT
- J to kg TNT
- J to MMBOE
- J to kBOE
- J to DGE
Everyday comparisons
Convert to joules
Frequently asked questions
What is a joule?
The joule is the SI unit of energy, work and heat.
How is the joule defined?
The work done by a force of one newton over one meter: 1 kg·m²/s².
How many kilocalories are in a joule?
One joule equals 0.000239005736 kilocalories.
How many kilowatt-hours are in a joule?
One joule equals 2.7777778e-7 kilowatt-hours.
How many British thermal units are in a joule?
One joule equals 0.00094781712 British thermal units.