Energy converter
From food Calories to electricity bills. A food Calorie is one kilocalorie (4.184 kJ).
1 kilocalorie (food Calorie) = 4.184 kilojoules
How it’s calculated
kJ = kcal × 4.184
- Multiply the value in kilocalories by 4.184.
- To go back, divide by 4.184 (or multiply by 0.2390057361).
- 1 kcal = 4.184 kJ · 1 kJ = 0.2390057361 kcal
Show worked solutionFactor, unit cancellation and rounding, step by step
Find the conversion factor
By definition 1 kcal = 4184 J and 1 kJ = 1000 J, so 1 kcal = 4.184 kJ. Source: NIST SP 811 / Handbook 44; BIPM SI Brochure (9th ed.) (SI prefixes and accepted units).
Multiply by the factor written as a fraction
Put kcal in the denominator so it cancels, leaving kJ.
Calculate (unrounded)
Round the answer
Rounded to 5 significant figures.
Answer: 4.184 kJ
1 kcal in other units
Batch convert kcal → kJ
- 1 kcal = 4.184 kJ
- 5 kcal = 20.92 kJ
- 10 kcal = 41.84 kJ
- 25 kcal = 104.6 kJ
Common energy conversions
Energy units and exact definitions
| Unit | System | Definition |
|---|---|---|
| Joule (J) | SI (metric) | Base unit |
| Kilojoule (kJ) | SI (metric) | 1 kJ = 1000 J |
| Megajoule (MJ) | SI (metric) | 1 MJ = 1000000 J |
| Calorie (thermochemical) (cal) | other | 1 cal = 4.184 J |
| Kilocalorie (food Calorie) (kcal) | other | 1 kcal = 4184 J |
| Watt-hour (Wh) | other | 1 Wh = 3600 J |
| Kilowatt-hour (kWh) | other | 1 kWh = 3600000 J |
| British thermal unit (IT) (BTU) | US & imperial (identical) | 1 BTU = 1055.055853 J |
| Therm (US) (thm) | US customary | 1 thm = 105480400 J |
| Foot-pound (energy) (ft·lbf) | US & imperial (identical) | 1 ft·lbf = 1.355817948 J |
| Electronvolt (eV) | other | 1 eV = 1.602176634e-19 J |
Kilocalories to kilojoules conversion table
| Kilocalories (kcal) | Kilojoules (kJ) |
|---|---|
| 0.1 kcal | 0.4184 kJ |
| 0.5 kcal | 2.092 kJ |
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 3 kcal | 12.552 kJ |
| 4 kcal | 16.736 kJ |
| 5 kcal | 20.92 kJ |
| 6 kcal | 25.104 kJ |
| 7 kcal | 29.288 kJ |
| 8 kcal | 33.472 kJ |
| 9 kcal | 37.656 kJ |
| 10 kcal | 41.84 kJ |
| 15 kcal | 62.76 kJ |
| 20 kcal | 83.68 kJ |
| 25 kcal | 104.6 kJ |
| 30 kcal | 125.52 kJ |
| 40 kcal | 167.36 kJ |
| 50 kcal | 209.2 kJ |
| 75 kcal | 313.8 kJ |
| 100 kcal | 418.4 kJ |
| 250 kcal | 1,046 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
Frequently asked questions
Which energy units can I convert?
joules (J), kilojoules (kJ), megajoules (MJ), calories (cal), kilocalories (kcal), watt-hours (Wh), kilowatt-hours (kWh), British thermal units (BTU), therms (thm), foot-pounds (ft·lbf), electronvolts (eV).
How accurate are the results?
Every unit is stored with its exact defining factor (NIST SP 811, NIST Handbook 44 or the BIPM SI Brochure). Calculations use double-precision arithmetic and are rounded only for display, to 5 significant figures by default (trailing zeros dropped, so 1 km shows as 1000 m). You can choose Auto (up to 10 digits), fixed decimals or more significant figures, or switch to scientific or engineering notation.