Home›Converters›Energy & Power›Energy Converter

Energy Converter

Energy & Power

Convert energy units instantly — joules, kWh, BTU, calories, and more. Essential for electricity bills, nutrition labels, and engineering calculations.

Reviewed by the thecalcu.com team · Last updated June 17, 2026

From
To
All conversionsfor 1 Kilowatt-hours (kWh)
Joules (J)3600000
Kilojoules (kJ)3600
Megajoules (MJ)3.6
Calories (cal)860420.65
Kilocalories / Calories (kcal)860.42065
British Thermal Units (BTU)3412.1416
Watt-hours (Wh)1000
Kilowatt-hours (kWh)1
Megawatt-hours (MWh)0.001
Electronvolts (eV)2.2469e+25
Foot-pounds (ft·lbf)2655223.7

What is a Energy?

An Energy Converter translates quantities of energy between the unit systems used across science, engineering, nutrition, and everyday life, joules, kilojoules, megajoules, kilowatt-hours, British Thermal Units, calories, kilocalories, watt-hours, megawatt-hours, electronvolts, and foot-pounds.

Energy is a single physical quantity, but it is expressed in radically different units depending on context. An Indian electricity bill counts units in kWh. Food packaging in India lists energy in kcal (often labelled simply as 'Calories'). Air conditioner cooling capacity is quoted in BTU per hour. Mechanical engineering specs use joules or foot-pounds. Nuclear and semiconductor physics uses electronvolts. This fragmentation makes direct comparison impossible without conversion.

In India, energy literacy is increasingly important. Electricity tariffs from DISCOMs like BESCOM, MSEDCL, TNEB, and CESC are structured in kWh slabs, understanding how appliance wattage translates into kWh consumed per month directly affects your electricity bill. The Bureau of Energy Efficiency (BEE) star ratings on refrigerators, ACs, and motors give Annual Energy Consumption (AEC) in kWh, which this converter can translate into joules or BTU for engineering cross-checks.

On the nutrition side, India's Food Safety and Standards Authority (FSSAI) mandates energy labelling in kcal per 100 g on packaged foods. Converting these to kJ is useful for those reading European nutrition research, and converting to joules helps when relating food intake to mechanical work output in sports science.

All 11 units in this converter are anchored to the joule as the SI base unit, making every conversion exact and mathematically consistent. For power-related calculations (energy per unit time), see the Power Converter.

Why Use an Energy Converter?

Electricity bills, appliance specs, food labels, fuel calorific values, and physics problems all use different energy units. The practical pain is not the arithmetic, it is knowing which formula to apply when the units are non-obvious.

  • Electricity vs heat: An AC is rated in BTU/hr of cooling but consumes energy in kWh. Understanding both sides of the equation, how many BTU of cooling you get per kWh of electricity, tells you the unit's COP (coefficient of performance). At ₹6/unit, a 5-star AC pulling 1.2 kW costs ₹7.20 per hour.
  • Food and exercise: A 500 kcal meal requires roughly 500/7 = 71 minutes of running at moderate pace to expend (at ~7 kcal/min). Seeing food energy in kJ or joules makes comparisons with biochemistry literature cleaner.
  • Fuel and calorific values: When comparing LPG (49 MJ/kg) against CNG (50 MJ/kg) or wood (15–17 MJ/kg), a converter that bridges MJ and kWh makes cost-per-unit-energy comparisons possible.

Who Should Use This Converter?

Electrical engineers and energy auditors calculating building energy performance in kWh alongside SI-based thermal calculations in joules or MJ. The Power Converter complements this for per-hour rates.

Nutritionists and fitness professionals in India who work with food databases in kcal but need to report in kJ for academic or export-market contexts.

HVAC engineers and AC technicians cross-referencing BTU cooling capacity with electrical power draw in watts or kW, standard practice when sizing commercial AC systems.

Students in physics, chemistry, and mechanical engineering encountering joules, calories, electronvolts, and BTU across different textbooks and lab contexts.

Homeowners and energy-conscious consumers wanting to understand their DISCOM electricity bill in joules or BTU for comparison with fuel costs. Pair this with the Calorie Calculator for diet and exercise energy planning.

What Insights Does the Energy Converter Give You?

The primary output shows your input in the target unit with full precision, 1 kWh renders as 3,600,000 J or 3,412.14 BTU without rounding.

The reference table displays all 11 units simultaneously. Entering 1 kWh, for instance, immediately shows: 3.6 MJ, 860.42 kcal, 3,412.14 BTU, 3,600 Wh, the complete picture of that quantity across every context.

Interpretation guide:

  • Sub-joule: electronvolt range, atomic and nuclear physics
  • 1–1,000 J: mechanical work, single-serve food items
  • 1–1,000 kJ: moderate physical activity, appliance short-run energy
  • 1–100 kWh: daily household consumption, vehicle range
  • MWh+: industrial, grid-scale, and large facility energy

How to use this Energy calculator

  1. Select your source unit from the FROM dropdown, e.g. Kilowatt-hours (kWh).
  2. Enter your numeric value in the input field, e.g. 10 for 10 kWh.
  3. Select the target unit from the TO dropdown, e.g. British Thermal Units (BTU).
  4. The converted result appears instantly, no button press needed.
  5. Use the ⇅ swap button to reverse FROM and TO in one click.
  6. Scroll to the reference table to see your value in all 11 units simultaneously.
  7. Copy the page URL to share or bookmark this exact conversion.

Formula & Methodology

All units convert to and from joules (J) using exact multipliers:

| Unit | Symbol | Joules (toBase) |
|---|---|---|
| Joule | J | 1 (base) |
| Kilojoule | kJ | 1,000 |
| Megajoule | MJ | 1,000,000 |
| Calorie (thermochemical) | cal | 4.184 |
| Kilocalorie | kcal | 4,184 |
| British Thermal Unit | BTU | 1,055.05585 |
| Watt-hour | Wh | 3,600 |
| Kilowatt-hour | kWh | 3,600,000 |
| Megawatt-hour | MWh | 3,600,000,000 |
| Electronvolt | eV | 1.602176634 × 10⁻¹⁹ |
| Foot-pound | ft·lbf | 1.3558179483 |

Conversion formula: Result = Input × (F_from ÷ F_to)

Worked example, AC energy cost in India:

A 1.5-tonne split AC draws 1.5 kW and is rated at 18,000 BTU/hr. How much does running it for 8 hours cost at ₹7/unit?

Energy consumed = 1.5 kW × 8 h = 12 kWh Cost = 12 × ₹7 = ₹84  Cross-check in BTU: 12 kWh × 3,412.14 BTU/kWh = 40,945 BTU Cooling delivered = 18,000 BTU/hr × 8 hr = 144,000 BTU

Common reference values:

| Quantity | Energy |
|---|---|
| 1 Indian electricity 'unit' | 1 kWh = 3.6 MJ |
| 500 kcal meal | 2,092 kJ = 0.581 kWh |
| 1 litre of petrol | ≈ 34 MJ ≈ 9.44 kWh |
| 1 kg LPG | ≈ 49 MJ ≈ 13.6 kWh |

Related Tools

You may also find these useful: Volume Converter.

Frequently Asked Questions

An energy converter is a tool that translates a quantity of energy from one unit to another, such as from kilowatt-hours (kWh) to British Thermal Units (BTU) or from kilocalories (kcal) to joules (J). Energy is measured in different units depending on context: electricity bills use kWh, food labels use kcal, engineering uses joules or BTU, and physics uses electronvolts. This converter handles all major energy units in a single step.
A calorie (cal) is the amount of energy needed to raise 1 gram of water by 1°C, while a kilocalorie (kcal) is 1,000 calories. The 'Calories' printed on food packaging in India and most countries are actually kilocalories, so a food item labelled '200 Calories' contains 200 kcal or 200,000 cal. This converter uses the thermochemical calorie (1 cal = 4.184 J exactly) as the standard definition.
Multiply the number of kilowatt-hours by 3,600,000 to get joules, since 1 kWh = 1,000 W × 3,600 s = 3,600,000 J. For example, 5 kWh = 5 × 3,600,000 = 18,000,000 J = 18 MJ. This conversion is useful when comparing electrical energy consumption with mechanical or thermal energy specifications.
A BTU (British Thermal Unit) is the energy needed to raise 1 pound of water by 1°F, equal to approximately 1,055 joules. In India, BTU ratings are used primarily for air conditioners, a 1.5-tonne AC is rated at roughly 18,000 BTU/hr of cooling capacity. When shopping for ACs, comparing BTU figures across brands is common, and this converter lets you cross-check against SI power units.
One kilowatt-hour (kWh) equals exactly 3,600,000 joules (3.6 MJ). This is because 1 kWh = 1 kilowatt × 1 hour = 1,000 watts × 3,600 seconds = 3,600,000 watt-seconds = 3,600,000 joules. Your monthly electricity bill from BESCOM, MSEDCL, or any Indian DISCOM is denominated in kWh (referred to as 'units' in common parlance).
An electronvolt (eV) is the kinetic energy gained by a single electron accelerated through 1 volt of electric potential, equal to exactly 1.602176634 × 10⁻¹⁹ joules (exact by 2019 SI redefinition). Electronvolts are used in atomic physics, nuclear physics, and semiconductor engineering to describe particle energies and bandgaps. They are not practical for everyday energy quantities but appear in material science and quantum mechanics contexts.
Indian electricity bills measure consumption in kilowatt-hours (kWh), commonly called 'units'. One unit = 1 kWh. If you run a 100-watt bulb for 10 hours, you consume 1 unit. Indian residential tariffs typically range from ₹3 to ₹9 per unit depending on the DISCOM and consumption slab, with higher slabs charged at progressively higher rates under the Time of Day (ToD) or block tariff structures.
Select the source unit from the FROM dropdown, for example, 'Kilowatt-hours (kWh)'. Enter your value in the input field, such as 10 for 10 kWh. Choose your target unit in the TO dropdown, such as 'British Thermal Units (BTU)'. The result appears instantly. Use the ⇅ swap button to reverse direction, and view the reference table below to see your value expressed in all 11 units at once.
Divide the BTU value by 3,412.14 to get kWh. This comes from 1 kWh = 3,600,000 J and 1 BTU = 1,055.06 J, so 1 kWh = 3,600,000 / 1,055.06 = 3,412.14 BTU. Reversing: 1 BTU = 1/3,412.14 kWh ≈ 0.000293 kWh. For air conditioner energy use in India, converting the BTU/hr cooling rating to kW helps estimate running costs at your local electricity tariff.
A foot-pound (ft·lbf) is an imperial unit of energy equal to the work done by a force of 1 pound-force acting through a distance of 1 foot, approximately 1.3558 joules. It is rarely used in everyday Indian contexts but appears in mechanical engineering specs, gun ballistics (muzzle energy), and American automotive manuals. Torque is also measured in ft·lbf, which is a separate quantity but the same unit dimensionally.
The average Indian household consumes between 90 and 300 kWh per month, depending on location, climate, and appliance usage. Urban households with air conditioning typically use 200–400 kWh in summer. The Bureau of Energy Efficiency (BEE) star-rating system on appliances helps consumers estimate monthly consumption: a 5-star 1.5-tonne split AC typically uses about 1 kWh per hour of operation at standard conditions.
Joules, kilojoules, and megajoules follow standard SI prefixes: 1 kJ = 1,000 J and 1 MJ = 1,000,000 J = 1,000 kJ. In nutrition, food energy is often expressed in kilojoules (kJ) on European labels, a medium-sized apple contains roughly 250 kJ (60 kcal). In fuels, calorific values are expressed in MJ per kg: natural gas is about 55 MJ/kg, petrol is approximately 44 MJ/kg.
Also known as
joule to caloriekWh to jouleBTU to jouleenergy unit conversioncalorie to joulewatt hour converterkilocalorie to jouleelectronvolt converterfood energy converterkJ to kcalenergy unit calculatorwatt hour to joule