Choose a conversion direction, enter one energy amount, and select the source and result units. Convert thermochemical calories or kilocalories to kWh or Wh, or convert kWh or Wh back to calories.

Convert energy amounts only. A food Calorie (Cal) is one kilocalorie (kcal). This calculator uses thermochemical calories.

1 food Calorie = 1 kcal = 1,000 small cal. Changing units converts the current quantity.

1 kWh = 3,600,000 joules; 1 Wh = 3,600 joules.

Assumptions Assumptions
  • Conversions are energy-to-energy only—no efficiency, metabolic rate, or losses are considered.
  • Calorie with a capital “C” (Cal) refers to the kilocalorie (kcal) used in food labels; small “cal” is the gram calorie.
  • Exact thermochemical definitions used: 1 Cal (kcal) = 4184 J; 1 cal = 4.184 J; 1 kWh = 3,600,000 J; 1 Wh = 3600 J.
  • Rounding shown in examples and tables may slightly affect the last digit.
When to Use This Calculator
  • Converting nutritional energy (Calories) to electrical energy (kWh) for comparisons.
  • Estimating how many kWh are equivalent to a meal or daily intake.
  • Translating appliance energy use (Wh/kWh) into dietary Calories and vice versa.
Input Definitions
  • Calories — choose Cal (kcal, food Calorie) or cal (small calorie).
  • Kilowatt-hours — choose kWh or Wh (1 kWh = 1000 Wh).
  • Conversions — kWh = kcal × 4184 ÷ 3,600,000 ≈ kcal ÷ 860.421; kcal = kWh × 3,600,000 ÷ 4184 ≈ kWh × 860.421.

Cal to kWh Formula

The following formulas convert thermochemical Calories (kcal) to kilowatt-hours and back, using joules as the base unit.

kWh = Cal × (4184) / (3,600,000)
Cal = kWh × (3,600,000) / (4184)
  • 1 Cal (kilocalorie) = 4184 J
  • 1 cal (small calorie) = 4.184 J
  • 1 kilowatt-hour (kWh) = 3,600,000 J
  • 1 watt-hour (Wh) = 3600 J

How do you convert Calories to kWh? Multiply Calories (kcal) by 4184 to get joules, then divide by 3,600,000 to get kWh (approximately, divide kcal by the rounded factor 860.421).

How do you convert kWh to Calories? Multiply kWh by 3,600,000 to get joules, then divide by 4184 to get kcal (approximately, multiply kWh by the rounded factor 860.421).

Cal to kWh Conversion Table

Calories (kcal) to Kilowatt-hours (kWh)
Calories (kcal) kWh
10.001162
50.005811
100.011622
200.023244
500.058111
1000.116222
1500.174333
2000.232444
2500.290556
3000.348667
4000.464889
5000.581111
7500.871667
1,0001.162222
1,5001.743333
2,0002.324444
2,5002.905556
3,0003.486667
* 1 kWh ≈ 860.421 kcal; 1 kcal ≈ 0.001162 kWh.

Example Problem

Convert 2,500 Cal (kcal) to kWh.

Choose kWh / Wh from calorie energy, enter 2,500 with Cal / kcal (food), and select kWh. The formula is kWh = Cal × 4184 ÷ 3,600,000.

kWh = 2,500 × 4184 ÷ 3,600,000 ≈ 2.905556 kWh