Joule (J)
The joule is the SI unit of energy — the work done when one newton moves an object one meter.
Joules quantify electricity bills (as kWh), food energy (as kcal), and scientific energy transfers.
Joule to Kilojoule
Convert joule to kilojoule instantly. Type in either field — results update live.
Instant
Private
Free
Energy Joule Kilojoule
1 joule = 0.001 kilojoules
Unit
Unit
Conversion table
Selected J values converted to kJ using the exact factor from this tool.
| J | kJ |
|---|---|
| 0.01 | 0.00001 |
| 0.1 | 0.0001 |
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 5 | 0.005 |
| 10 | 0.01 |
| 20 | 0.02 |
| 50 | 0.05 |
| 100 | 0.1 |
| 1,000 | 1 |
How to convert
Exact conversion factors in both directions, plus a worked example.
1 J = 0.001 kJ
1 kJ = 1000 J
To convert joule to kilojoule, multiply by 0.001.
To convert kilojoule to joule, multiply by 1000.
Example: convert 10 J to kJ
10 × 0.001 = 0.01 kJ
About these units
Short background on the units used in this conversion.
Kilojoule (kJ)
A kilojoule is one thousand joules — the metric counterpart to the kilocalorie on food labels.
Kilojoules appear on Australian and European nutrition labels alongside or instead of kilocalories.
Frequently asked questions
How many kilojoules are in one joule?
One joule equals 0.001 kilojoules. Multiply your joules value by 0.001 to convert to kilojoules.
What is the conversion formula?
kJ = J × 0.001The reverse is
J = kJ × 1,000, using the same exact factors as this converter.Is this Joule to Kilojoule converter private?
Yes. All calculations run locally in your browser. Nothing you type is sent to a server.
All joule conversions
Jump to any energy conversion starting from joule — including the reverse direction and every other unit in our dataset.
kilojoule (kJ) → joule (J)
joule (J) → megajoule (MJ)joule (J) → gigajoule (GJ)joule (J) → kilowatt-hour (kW·h)joule (J) → watt-hour (W·h)joule (J) → calorie (nutritional / food calorie) (Cal)joule (J) → kilocalorie (it) (kcal (IT))joule (J) → kilocalorie (thermochemical) (kcal (th))joule (J) → calorie (it) (cal (IT))joule (J) → calorie (thermochemical) (cal (th))joule (J) → british thermal unit (it) (Btu (IT))joule (J) → british thermal unit (thermochemical) (Btu (th))joule (J) → foot-pound (ft·lbf)joule (J) → newton meter (N·m)joule (J) → horsepower hour (mechanical) (hp·h)joule (J) → horsepower (metric) hour (metric hp·h)joule (J) → millijoule (mJ)joule (J) → microjoule (µJ)joule (J) → nanojoule (nJ)joule (J) → attojoule (aJ)joule (J) → megaelectron-volt (MeV)joule (J) → kiloelectron-volt (keV)joule (J) → electron-volt (eV)joule (J) → ergjoule (J) → gigawatt-hour (GW·h)joule (J) → megawatt-hour (MW·h)joule (J) → kilowatt-second (kW·s)joule (J) → watt-second (W·s)joule (J) → mega british thermal unit (it) (MBtu (IT))joule (J) → ton-hour (refrigeration) (ton·h)joule (J) → fuel oil equivalent @ kiloliter (kL oil eq)joule (J) → fuel oil equivalent @ barrel (us) (bbl oil eq)joule (J) → gigaton (tnt) (Gton)joule (J) → megaton (tnt) (Mton)joule (J) → kiloton (tnt) (kton)joule (J) → ton (explosives / tnt) (ton TNT)joule (J) → dyne centimeter (dyn·cm)joule (J) → gram-force meter (gf·m)joule (J) → gram-force centimeter (gf·cm)joule (J) → kilogram-force centimeter (kgf·cm)joule (J) → kilogram-force meter (kgf·m)joule (J) → kilopond meter (kp·m)joule (J) → pound-force foot (lbf·ft)joule (J) → pound-force inch (lbf·in)joule (J) → ounce-force inch (ozf·in)joule (J) → inch-pound (in·lbf)joule (J) → inch-ounce (in·ozf)joule (J) → poundal foot (pdl·ft)joule (J) → thermjoule (J) → therm (ec)joule (J) → therm (us)joule (J) → hartree energy (Eh)joule (J) → rydberg constant (Ry)