A kilocalorie is 1,000 calories.
Kilocalories to Microjoules Converter — kcal to uJ
Convert Kilocalorie (kcal) to Microjoule (uJ) using the exact conversion factor (1 kilocalorie = 4,184,000,000 microjoule). See the formula, worked examples, and conversion table.
Kilocalories to Microjoules converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
Microjoule is 0.000001 joule units.
Result = input x 4184 / 1e-6.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Kilocalories to Microjoules
Kilocalorie and Microjoule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: A kilocalorie is 1,000 calories, and microjoule is 0.000001 joule units.
Formula
microjoules = kilocalories × 4184000000
This factor comes from each unit's defined relationship to the category's base unit: 1 kilocalorie equals 4184 base units, and 1 microjoule equals 0.000001 base units, so dividing one by the other gives the direct kilocalorie-to-microjoule factor of 4184000000.
Simple example
1 kcal × 4184000000 = 4,184,000,000 uJ
1 kilocalorie = 4,184,000,000 microjoules.
Real-world example
100 kcal × 4184000000 = 418,400,000,000 uJ
100 kilocalories = 418,400,000,000 microjoules.
Conversion table
| Kilocalorie (kcal) | Microjoule (uJ) |
|---|---|
| 1 kcal | 4,184,000,000 uJ |
| 10 kcal | 41,840,000,000 uJ |
| 100 kcal | 418,400,000,000 uJ |
| 500 kcal | 2.092e+12 uJ |
| 1,000 kcal | 4.184e+12 uJ |
| 2,000 kcal | 8.368e+12 uJ |
Reverse conversion: Microjoule to Kilocalorie
1 uJ × 2.390057e-10 = 2.390057e-10 kcal
1 microjoule = 2.390057e-10 kilocalories.
kilocalories = microjoules × 2.390057e-10
For a page dedicated to this direction, see Microjoule to Kilocalorie.
Understanding the Kilocalorie (kcal)
A kilocalorie is 1,000 calories.
Understanding the Microjoule (uJ)
Microjoule is 0.000001 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many microjoules are in 1 kilocalorie?
1 kilocalorie equals 4,184,000,000 microjoules, using the exact defined conversion factor rather than an estimate.
How do I convert kilocalorie to microjoule?
Multiply the kilocalorie value by 4184000000. The converter above does this instantly to whatever precision you set.
How do I convert microjoule back to kilocalorie?
Use the reverse factor: 1 microjoule equals 2.390057e-10 kilocalories. You can also use the swap control in the converter above to flip the direction instantly.
What is a kilocalorie?
Kilocalorie (kcal) is a unit of energy.
What is a microjoule?
Microjoule (uJ) is a unit of energy.
Is the kilocalorie to microjoule conversion exact?
Yes. Both kilocalorie and microjoule are defined by fixed standards rather than physical artifacts, so the factor of 4184000000 used above is exact to as many digits as you choose to display.