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Converters

Energy & Power Converter

Convert joules, kWh, calories/kilocalories, BTU, and foot-pounds — connect electricity bills, food labels, and physics units.

Joules (J)1
Kilojoules (kJ)0.001
Kilowatt-hours (kWh)0
Calories (cal)0.239006
Kilocalories (kcal)0.000239
BTU0.000948
Foot-pounds (ft·lb)0.737562

Anchored conversions from Joules (J) use exact internationally agreed factors. Everything is computed locally, instantly.

Power Is Not Energy: The kW vs kWh Confusion

kW measures power (a rate), kWh measures energy (a quantity over time) — confusing them is the everyday energy-unit error. A 2 kW heater running 3 hours consumes 6 kWh. The same distinction explains EV range claims: a 60 kWh battery at 15 kWh/100km consumption gives 400 km. Food calories (cal) convert to joules at 4.184 J per calorie, and the "Calories" on packaging are kilocalories (1,000 cal) — a factor of a thousand hidden in capitalization.

How the Conversion Works

  1. Enter an energy value in any unit; all others convert at once.
  2. Food "calories" are correctly treated as kilocalories (kcal), the industry convention.
  3. Power units (watts, horsepower) link in: run time at a given power converts to energy.
  4. Context notes connect units to bills (kWh) and nutrition (kcal).
Formula & Technical Standard
1 kWh = 3.6 MJ (exact) · 1 kcal = 4184 J (exact) · 1 BTU = 1055.05585 J (IT definition).

Conversion Example

Appliance running cost
Input: 2 kWh (a 2000 W heater for 1 h)
Output: 7,200,000 J · 1,721 kcal
The same energy expressed in physics and nutrition terms — useful for intuition about scale.
Air conditioner rating
Input: 12,000 BTU/h
Output: ≈ 3.52 kW of cooling power
BTU ratings on AC units convert to the kilowatt figure used in most other countries.

Common Questions

Why do food labels say calories but mean kilocalories?

The food "Calorie" (capital C) is a kilocalorie: 4184 J. The convention stuck from 19th-century chemistry; this tool follows it.

What is the difference between energy and power?

Power (watts) is the rate of energy flow; energy (joules, kWh) is the accumulated amount. 1 kWh is the energy of 1 kW sustained for one hour.

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Hardware

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Calculate active electrical draw, daily/monthly kWh consumption, and electricity bill costs.

Converters

Power Converter

Convert watts, kilowatts, mechanical and metric horsepower, and BTU/h — the units used across engines, PCs, and HVAC.