Convert Kilocalorie to Kilojoule
1 kilocalorie = 4.184 kilojoule (kJ). For example, 10 kilocalorie = 41.84 kilojoule and 100 kilocalorie = 418.4 kilojoule. Type any value below to convert kilocalorie to kilojoule both ways — it runs entirely in your browser.
Quick answer: Kilocalorie to Kilojoule
1 Kilocalorie = 4.184 Kilojoule (kcal → kJ). To convert kilocalorie to kilojoule, multiply by 4.184. To convert kilojoule to kilocalorie, multiply by 0.2390057. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common kilocalorie-to-kilojoule questions.
How to convert Kilocalorie to Kilojoule
To convert kilocalorie to kilojoule, multiply the number of kilocalorie by the conversion factor 4.184, because 1 kcal = 4.184 kJ. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 kJ = 0.2390057 kcal, so you divide by 4.184 (or multiply by 0.2390057) to turn kilojoule back into kilocalorie.
kJ = kcal × 4.184 ·
kcal = kJ × 0.2390057
- Write down the value you want to convert, in kilocalorie.
- Multiply it by 4.184.
- The result is the same area/length/quantity expressed in kilojoule.
Kilocalorie to Kilojoule — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 kilocalorie is 20.92 kilojoule because 5 kcal × 4.184 = 20.92 kJ.
| Kilocalorie | Calculation | Kilojoule |
|---|---|---|
| 1 kcal | 1 kcal × 4.184 = 4.184 kJ | 4.184 kJ |
| 2 kcal | 2 kcal × 4.184 = 8.368 kJ | 8.368 kJ |
| 3 kcal | 3 kcal × 4.184 = 12.552 kJ | 12.552 kJ |
| 5 kcal | 5 kcal × 4.184 = 20.92 kJ | 20.92 kJ |
| 7 kcal | 7 kcal × 4.184 = 29.288 kJ | 29.288 kJ |
| 10 kcal | 10 kcal × 4.184 = 41.84 kJ | 41.84 kJ |
| 12 kcal | 12 kcal × 4.184 = 50.208 kJ | 50.208 kJ |
| 15 kcal | 15 kcal × 4.184 = 62.76 kJ | 62.76 kJ |
| 20 kcal | 20 kcal × 4.184 = 83.68 kJ | 83.68 kJ |
| 25 kcal | 25 kcal × 4.184 = 104.6 kJ | 104.6 kJ |
| 50 kcal | 50 kcal × 4.184 = 209.2 kJ | 209.2 kJ |
| 100 kcal | 100 kcal × 4.184 = 418.4 kJ | 418.4 kJ |
Common Kilocalorie to Kilojoule conversions
These are the kilocalorie-to-kilojoule values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 kilocalorie = 4.184 kilojoule
- 2 kilocalorie = 8.368 kilojoule
- 2.5 kilocalorie = 10.46 kilojoule
- 3 kilocalorie = 12.552 kilojoule
- 4 kilocalorie = 16.736 kilojoule
- 5 kilocalorie = 20.92 kilojoule
- 6 kilocalorie = 25.104 kilojoule
- 7 kilocalorie = 29.288 kilojoule
- 8 kilocalorie = 33.472 kilojoule
- 9 kilocalorie = 37.656 kilojoule
- 10 kilocalorie = 41.84 kilojoule
- 12 kilocalorie = 50.208 kilojoule
- 15 kilocalorie = 62.76 kilojoule
- 20 kilocalorie = 83.68 kilojoule
- 25 kilocalorie = 104.6 kilojoule
- 30 kilocalorie = 125.52 kilojoule
- 50 kilocalorie = 209.2 kilojoule
- 75 kilocalorie = 313.8 kilojoule
- 100 kilocalorie = 418.4 kilojoule
- 200 kilocalorie = 836.8 kilojoule
- 500 kilocalorie = 2,092 kilojoule
- 1000 kilocalorie = 4,184 kilojoule
Kilocalorie to Kilojoule conversion chart (both directions)
The chart below converts kilocalorie to kilojoule and kilojoule to kilocalorie side by side, so it works whichever way you need. 1 kilocalorie = 4.184 kilojoule, and 1 kilojoule = 0.2390057 kilocalorie.
| Kilocalorie → Kilojoule | Kilojoule → Kilocalorie |
|---|---|
| 0.25 kcal = 1.046 kJ | 0.25 kJ = 0.05975143 kcal |
| 0.5 kcal = 2.092 kJ | 0.5 kJ = 0.1195029 kcal |
| 1 kcal = 4.184 kJ | 1 kJ = 0.2390057 kcal |
| 2 kcal = 8.368 kJ | 2 kJ = 0.4780115 kcal |
| 3 kcal = 12.552 kJ | 3 kJ = 0.7170172 kcal |
| 4 kcal = 16.736 kJ | 4 kJ = 0.9560229 kcal |
| 5 kcal = 20.92 kJ | 5 kJ = 1.195029 kcal |
| 6 kcal = 25.104 kJ | 6 kJ = 1.434034 kcal |
| 7 kcal = 29.288 kJ | 7 kJ = 1.67304 kcal |
| 8 kcal = 33.472 kJ | 8 kJ = 1.912046 kcal |
| 9 kcal = 37.656 kJ | 9 kJ = 2.151052 kcal |
| 10 kcal = 41.84 kJ | 10 kJ = 2.390057 kcal |
| 12 kcal = 50.208 kJ | 12 kJ = 2.868069 kcal |
| 15 kcal = 62.76 kJ | 15 kJ = 3.585086 kcal |
| 20 kcal = 83.68 kJ | 20 kJ = 4.780115 kcal |
| 25 kcal = 104.6 kJ | 25 kJ = 5.975143 kcal |
| 30 kcal = 125.52 kJ | 30 kJ = 7.170172 kcal |
| 40 kcal = 167.36 kJ | 40 kJ = 9.560229 kcal |
| 50 kcal = 209.2 kJ | 50 kJ = 11.95029 kcal |
| 75 kcal = 313.8 kJ | 75 kJ = 17.92543 kcal |
| 100 kcal = 418.4 kJ | 100 kJ = 23.90057 kcal |
| 150 kcal = 627.6 kJ | 150 kJ = 35.85086 kcal |
| 200 kcal = 836.8 kJ | 200 kJ = 47.80115 kcal |
| 250 kcal = 1,046 kJ | 250 kJ = 59.75143 kcal |
| 500 kcal = 2,092 kJ | 500 kJ = 119.5029 kcal |
| 1000 kcal = 4,184 kJ | 1000 kJ = 239.0057 kcal |
Kilocalorie vs Kilojoule: which is bigger?
A kilocalorie is the larger unit: one kilocalorie equals 4.184 kilojoules. Put another way, you need 4.184 kilojoules to make a single kilocalorie.
What is a Kilocalorie? History, origin and usage
The kilocalorie is 1,000 small calories, and it is the unit behind the familiar food “Calorie” (often written with a capital C). It descends from the calorimetry of Nicolas Clément and the 19th-century nutrition science of Marcellin Berthelot and Wilbur Atwater, who needed a human-scale unit for the energy in food.
The kilocalorie is the energy figure on nutrition labels in the United States and many other countries, where it is simply called the “calorie.” Dietitians, food scientists and fitness apps use kcal to track energy intake and expenditure.
When a label says a food has “250 calories,” it means 250 kilocalories — 250,000 of the physicists’ small calories. The macronutrients differ in energy density: fat supplies about 9 kcal per gram, while carbohydrate and protein each supply about 4 kcal per gram.
What is a Kilojoule? History, origin and usage
The kilojoule is simply 1,000 joules, formed with the SI “kilo” prefix, and it inherits the joule’s heritage from James Prescott Joule’s heat experiments. It became the practical everyday multiple of the joule because single joules are inconveniently small for food, fuel and exercise energy.
The kilojoule is the energy figure on nutrition labels across Europe, Australia and many other countries, usually printed alongside (or instead of) kilocalories. It is also handy for stating the energy of small chemical reactions, batteries and household tasks.
Australia and New Zealand use kilojoules almost exclusively for food energy, so a chocolate bar there is rated in kJ rather than Calories. One food “Calorie” (a kilocalorie) is about 4.184 kJ, which is why kilojoule figures on labels look roughly four times larger than the familiar calorie counts.
Convert 1 Kilocalorie to other units
It can help to see a kilocalorie next to the other units it is commonly compared with. One kilocalorie (kcal) is equal to:
| 1 Kilocalorie equals | Unit |
|---|---|
| 4,184 J | Joule |
| 4,184 N·m | Newton-metre |
| 4.184 kJ | Kilojoule |
| 0.004184 MJ | Megajoule |
| 1.162222 Wh | Watt-hour |
| 0.001162222 kWh | Kilowatt-hour |
| 0.000001162222 MWh | Megawatt-hour |
| 3,085.96 ft·lbf | Foot-pound |
| 26,114,470,000,000,000 MeV | Megaelectronvolt |
| 1,000 cal | Calorie |
| 3.965667 BTU | British Thermal Unit |
Convert 1 Kilojoule to other units
One kilojoule (kJ) is equal to:
| 1 Kilojoule equals | Unit |
|---|---|
| 1,000 J | Joule |
| 1,000 N·m | Newton-metre |
| 0.001 MJ | Megajoule |
| 0.2777778 Wh | Watt-hour |
| 0.0002777778 kWh | Kilowatt-hour |
| 0.0000002777778 MWh | Megawatt-hour |
| 737.5621 ft·lbf | Foot-pound |
| 6,241,509,000,000,000 MeV | Megaelectronvolt |
| 239.0057 cal | Calorie |
| 0.2390057 kcal | Kilocalorie |
| 0.9478171 BTU | British Thermal Unit |
Tips for converting Kilocalorie to Kilojoule
- To go from kilocalorie to kilojoule, multiply by 4.184; to go back, divide by 4.184 (or multiply by 0.2390057).
- For a quick mental estimate, remember that 1 kilocalorie ≈ 4.184 kilojoule, so 10 kilocalorie ≈ 41.84 kilojoule.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Kilocalorie to Kilojoule converter
Type a number into the Kilocalorie field and the equivalent in Kilojoule appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Kilojoule field to convert the other way (kilojoule to kilocalorie). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 kcal = 4.184 kJ), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for kilocalorie-to-kilojoule conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST — Definitions of the SI base units — the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
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Frequently asked questions
- How many kilojoule are in 1 kilocalorie?
- 1 kilocalorie = 4.184 kilojoule (kJ). To convert any number of kilocalorie to kilojoule, multiply by 4.184.
- How do I convert kilocalorie to kilojoule?
- Multiply the number of kilocalorie by 4.184. For example, 10 kilocalorie = 10 × 4.184 = 41.84 kilojoule, and 25 kilocalorie = 104.6 kilojoule.
- How many kilocalorie are in 1 kilojoule?
- 1 kilojoule = 0.2390057 kilocalorie. So to convert kilojoule back to kilocalorie, multiply by 0.2390057.
- What is the formula to convert kilocalorie to kilojoule?
- kilojoule = kilocalorie × 4.184. The reverse formula is kilocalorie = kilojoule × 0.2390057.
- How much is 100 kilocalorie in kilojoule?
- 100 kilocalorie = 418.4 kilojoule. (And 1000 kilocalorie = 4,184 kilojoule.)
- Which is bigger, a kilocalorie or a kilojoule?
- A kilocalorie is larger: 1 kilocalorie = 4.184 kilojoule.
- Is this kilocalorie to kilojoule converter accurate?
- Yes — every value is computed from the exact 4.184 kJ per kcal factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert kilojoule to kilocalorie too?
- Yes. The converter works both ways — enter a value in either field. 1 kilojoule = 0.2390057 kilocalorie.