Convert Kilocalorie to Watt-Hour (kcal → Wh)

Converting kilocalories to watt-hours is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in kilocalories

   Start with the number of kilocalories (kcal) you want to convert.
2. 2
   Multiply by 1.162222

   The conversion factor from kcal to Wh is 1.162222. Multiply your value by this number.
3. 3
   Read the result in watt-hours

   The result is your value in watt-hours (Wh).

Multiply the value in kilocalories by 1.162222. For the reverse direction, multiply by 0.860421.

• ✓1 kcal = 4.184 kJ.
• ✓US "Calorie" (with capital C) = 1 kcal.
• ✓Apps and smartwatches track active energy in kcal.

• ✗Reading food "Calories" as gram calories — factor of 1000 off.
• ✗Treating all calorie values as comparable — macros (fat, protein, carb) differ in energy density.
• ✗Counting kcal without portion size leads to underestimates.

What is the Kilocalorie?

The kilocalorie equals 1,000 small calories or exactly 4.184 kilojoules and is the universal unit for measuring dietary energy in food. Confusingly, on US food labels and in popular usage, 'Calorie' (capital C) means kilocalorie — so a 200-Calorie cookie is actually 200,000 small calories, or 200 kcal. This convention dates to American chemist Wilbur Atwater's 19th-century nutrition research. Recommended daily intake is roughly 2,000 kcal for women and 2,500 kcal for men. The kilocalorie remains the everyday food-energy unit in the United States, while European labels show both kJ and kcal. Athletes track caloric burn during exercise in kcal: running burns about 100 kcal per mile. The kcal relates to the kilojoule (4.184 kJ = 1 kcal), the joule (1 kcal = 4,184 J), and the BTU (1 BTU ≈ 0.252 kcal). Marathon runners burn roughly 2,600 kcal during a 42-km race.

• Nutrition labels worldwide
• Diet and weight-management tracking
• Dietetics and clinical nutrition

What is the Watt-Hour?

The watt-hour equals exactly 3,600 joules and is the standard unit for small-battery capacity, household electrical energy, and renewable-energy storage. A smartphone battery stores roughly 12–15 Wh, a laptop battery 50–100 Wh, and an electric car battery 60,000–100,000 Wh (60–100 kWh). The watt-hour represents the energy delivered by a 1-watt device running for 1 hour. It is the natural unit for connecting power (watts) to time, which is why electric utilities bill in kilowatt-hours. The watt-hour relates to the joule (3,600 J = 1 Wh), the kilowatt-hour (1,000 Wh = 1 kWh), and the BTU (1 Wh ≈ 3.412 BTU). Battery capacity, solar panel output (Wh per day), and energy storage system specifications all rely on the watt-hour as the base small-energy unit.

• Laptop and phone battery capacity
• Portable power banks and UPS
• Home solar panel daily output