Select a category and enter your values below
Multiple conversions
To convert from Kilojoule (kJ) to Watt-second (Ws), use the following formula:
Watt-second (Ws)
= 1000× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Watt-minute (Wm), use the following formula:
Watt-minute (Wm)
= 1000 × 160× Kilojoule (kJ)
= 16.666666666666666667× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Watt-hour (Wh), use the following formula:
Watt-hour (Wh)
= 1000 × 160 × 60× Kilojoule (kJ)
= 0.27777777777777777778× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Milliwatt-hour (mWh), use the following formula:
Milliwatt-hour (mWh)
= 1000 × 13.6× Kilojoule (kJ)
= 277.77777777777777778× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Kilowatt-hour (kWh), use the following formula:
Kilowatt-hour (kWh)
= 1000 × 160 × 60 × 1000× Kilojoule (kJ)
= 0.00027777777777777777778× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Megawatt-hour (MWh), use the following formula:
Megawatt-hour (MWh)
= 1000 × 160 × 60 × 106× Kilojoule (kJ)
= 2.7777777777777777778× 10-7× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Gigawatt-hour (GWh), use the following formula:
Gigawatt-hour (GWh)
= 1000 × 160 × 60 × 109× Kilojoule (kJ)
= 2.7777777777777777778× 10-10× Kilojoule (kJ)
To convert energy from kilojoules (kJ) to joules (J), multiply by 1,000.
The kilo prefix means one thousand, so the conversion is an exact three-place decimal shift. Divide by 1,000 to go from J back to kJ.
A physics problem gives the kinetic energy of a vehicle as 1.8 kJ and asks for the braking force over a 12 m stopping distance, which requires base SI units:
The conversion is the necessary first step because the joule — not the kilojoule — is what cancels cleanly against newtons and meters.
| kJ | J |
|---|---|
| 0.1 | 100 |
| 1 | 1,000 |
| 1.8 | 1,800 |
| 4.184 | 4,184 |
| 100 | 100,000 |
| 2,000 | 2,000,000 |
Kilojoules dominate wherever energy is stated — food labels (a 2,000-calorie diet is about 8,400 kJ), chemistry's reaction enthalpies (kJ/mol), appliance and HVAC documentation — while joules dominate wherever energy is computed, because SI formulas deliver and consume base units. That split makes kJ→J among the most frequently performed conversions in science education and one of the most instructive: it teaches that prefixes are bookkeeping, not physics. In practice the multiplication appears at the boundary of every worked problem, as in the example above, and at the boundary of every calorimetry experiment, where a measured temperature rise gives joules but the reference tables answer in kJ/mol. The error mode is well documented in exam papers everywhere: carrying a kJ value into a formula expecting J understates the answer by a thousandfold, and because 4.184 J/(g·°C) — water's specific heat — looks so similar to the 4.184 kJ of a food calorie's thousand-fold cousin, thermochemistry is where the slip hides best. Writing units beside every number and cancelling them explicitly remains the one reliable vaccine.
To convert from Kilojoule (kJ) to Megajoule (MJ), use the following formula:
Megajoule (MJ)
= 1000 × 1106× Kilojoule (kJ)
= 11000× Kilojoule (kJ)
= 0.001× Kilojoule (kJ)
To convert from Kilojoule (kJ) to Gigajoule (GJ), use the following formula:
Gigajoule (GJ)
= 1000 × 1109× Kilojoule (kJ)
= 1106× Kilojoule (kJ)
= 10-6× Kilojoule (kJ)
To convert from Kilojoule (kJ) to calorie (cal), use the following formula:
calorie (cal)
= 1000 × 14.184× Kilojoule (kJ)
= 239.00573613766730402× Kilojoule (kJ)
With 14.184 is the ratio between the base units calorie (cal) and Joule (J).
To convert from Kilojoule (kJ) to Kilocalorie (kcal), use the following formula:
Kilocalorie (kcal)
= 1000 × 14.184 × 11000× Kilojoule (kJ)
= 14.184× Kilojoule (kJ)
= 0.23900573613766730402× Kilojoule (kJ)
With 14.184 is the ratio between the base units calorie (cal) and Joule (J).
A kilojoule (kJ) is a unit used to measure energy.
Just like a kilometer is 1,000 meters, a kilojoule is 1,000 joules. Kilojoules are part of the International System of Units (SI), the modern form of the metric system.
They are used worldwide to measure energy in food, physics, and everyday life.
Key Takeaways:
In nutrition, kilojoules (kJ) are the international standard for measuring the energy we get from food and drinks.
You'll often see them listed alongside calories (cal) on nutrition labels, especially outside of the United States.
Understanding the relationship between them is easy. The conversion is simple: 1 calorie is about 4.2 kilojoules.
Knowing this helps you accurately track your energy intake and easily compare food products, no matter where you are in the world.
As a multiple of the joule, the kilojoule (kJ) is a fundamental unit for measuring work and energy in scientific fields like physics and chemistry.
One kilojoule (1,000 joules) is roughly the energy needed to lift a 100-kg (220-lb) object one meter off the ground.
This standardization allows scientists to make precise and consistent energy calculations in experiments and research.
Beyond food labels and science labs, kilojoules help quantify the energy we use for everyday activities and appliances.
Thinking in kilojoules offers a practical way to understand and manage your personal energy expenditure.
For example: