Choose an energy or power conversion direction, enter one value, and select the source and result units. Thermochemical calories are the default for food energy; explicitly labeled International Table conversions remain available.
Assumptions Assumptions
- Default thermochemical units: 1 cal = 4.184 J; 1 kcal = 1 food Calorie = 4184 J. IT options use the International Table definition: 1 cal = 4.1868 J and 1 kcal = 4186.8 J.
- Rates are pure energy-per-time conversions; no efficiency or heat-loss factors are applied.
- Time base: 1 min = 60 s; 1 h = 3600 s; 1 day = 86400 s; power: 1 kW = 1000 W.
- Values are treated as steady (average) rates over the selected time unit.
When to Use This Calculator
- Expressing nutrition or metabolic energy rates (Cal/h, kcal/min) in W or kW, without predicting electrical output.
- Relating heat-generation/absorption rates to equipment power ratings.
- HVAC, lab, or classroom problems involving energy rate conversions.
Input Definitions
- Calorie Rate — choose cal, kcal, or Cal and a time unit (s, min, h, day).
- Power — choose output in W or kW.
- Quick refs — 1 cal/s = 4.184 W; 1 kcal/s (Cal/s) = 4.184 kW; 1 Cal/h ≈ 1.162 W.
- All Unit Converters
- Cal to BTU Conversion Calculator
- Cal to kWh Conversion Calculator
- kcal to kW Conversion Calculator
- Joules to kW Calculator
- kJ to kW Calculator
Cal to kW Conversion Formula
Because a calorie measures energy and a kilowatt measures power (energy per unit time), the conversion you need depends on what you are starting with. Use the energy formula to convert calories to kilowatt-hours, and the power formula to convert a calorie rate to kilowatts.
E_{kWh} = E_{kcal} \times (4184 / 3600000)
Where:
- E_kWh is the energy in kilowatt-hours (kWh)
- E_kcal is the energy in kilocalories (kcal)
- 4184/3,600,000 ≈ 0.001162222222 is the number of kWh in one thermochemical kcal
P_{kW} = R_{kcal/h} \times (4184 / 3600000)
Where:
- P_kW is the power in kilowatts (kW)
- R_kcal/h is the calorie rate in kilocalories per hour (kcal/h)
- 4184/3,600,000 ≈ 0.001162222222 kW is equivalent to a steady rate of one thermochemical kcal/h
One food Calorie (Cal) equals one kilocalorie, so a Calorie value uses the same factors as a kcal value. A small calorie (cal) is one thousandth of a kilocalorie.
Common Calorie and Kilowatt Conversions
These reference values use the default thermochemical calorie definition and are rounded as shown. IT options use different factors.
| Energy input | Equals (kWh) |
|---|---|
| 1 kcal | ≈ 0.001162222 kWh |
| 100 kcal | ≈ 0.116222222 kWh |
| 1,000 kcal | ≈ 1.162222222 kWh |
| 2,000 Cal (food) | ≈ 2.324444444 kWh |
| 1 cal | ≈ 0.000001162222 kWh |
| Rate input | Equals (kW) |
|---|---|
| 1 kcal/h | ≈ 0.001162222 kW |
| 860 kcal/h | ≈ 0.999511111 kW |
| 1 kcal/s | 4.184 kW |
| 1 cal/s | 0.004184 kW |
Example Problems
Example 1. Choose kWh / Wh from calorie energy. Enter 500 with kcal (th), and select kWh. The result is 500 × 4184/3,600,000 ≈ 0.581111111 kWh.
Example 2. Choose kW / W from calorie rate. Enter 2,000 with kcal (th)/h, and select kW. The equivalent rate is 2,000 × 4184/3,600,000 ≈ 2.324444444 kW; no efficiency is applied.
Frequently Asked Questions
Can you convert calories directly to kilowatts? Not directly. A calorie is a unit of energy and a kilowatt is a unit of power, which is energy per unit of time. To reach kilowatts you need a rate such as kilocalories per hour. To convert a plain calorie amount, convert to kilowatt-hours instead.
What is the difference between kW and kWh? A kilowatt (kW) measures how fast energy is used or produced at a given moment. A kilowatt-hour (kWh) measures a total amount of energy, equal to one kilowatt sustained for one hour.
Is a food Calorie the same as a kilocalorie? Yes. The Calorie shown on nutrition labels, written with a capital C, equals one kilocalorie (1,000 small calories), so it uses the same conversion factors in this calculator.
