Energy Converter

What is the Energy Converter?

Energy is the capacity to do work, measured in many units depending on context: joules (SI standard), calories (food & chemistry), kilowatt-hours (electricity), British thermal units (HVAC & heating), ergs (physics), foot-pounds (mechanics), and more. An energy converter translates these seamlessly so 1 kilowatt-hour (kWh) becomes 3.6 million joules or 860 kilocalories—all at once.

How it works

Enter a value in any energy unit and select the target unit. The converter applies precise conversion factors (e.g. 1 joule = 0.000239 calories, 1 kWh = 3.6 MJ). Results display instantly with full precision, letting you copy or compare multiple conversions side by side.

Examples

Input	Result	Notes
100 joules to calories	23.9 calories	Food and lab work often use calories; knowing 100 J ≈ 24 cal helps compare heat values.
1 kilowatt-hour to joules	3,600,000 joules (3.6 MJ)	Electricity bills measure kWh; converting to joules shows the absolute energy content.
500 BTU to joules	527,778 joules	HVAC systems quote capacity in BTU; engineers need joules for calculation.

How to use the Energy Converter

Enter the energy value you want to convert.
Select the unit of your input (joules, calories, kWh, BTU, erg, foot-pound, etc.).
Choose the target unit from the dropdown.
View the converted result instantly.
Click to copy the result or convert another value.
Bookmark for quick access to daily conversions.

Benefits

Handles 15+ energy units so you never need multiple converters.
Instant, accurate results with no waiting or manual calculations.
Useful for food labels, electricity bills, physics homework, and engineering work.
Free and offline (no account or downloads required).
Mobile-friendly interface works on phones, tablets, and desktops.
Compare energy values across scientific, industrial, and everyday contexts.

Tips & common mistakes

Common mistakes

Confusing calories (small c, ≈4.186 joules) with kilocalories (kcal or Cal, food labels, ≈4,186 joules). Food labels show kilocalories.
Forgetting that BTU and foot-pounds are Anglo-American units; SI (joules) is standard in science and most of the world.
Mixing up kilowatt-hours (energy, kWh) with kilowatts (power, kW); kWh = power × time.
Assuming all calories are alike; nutritional calories are kilocalories, but chemistry uses small calories.

Tips

Bookmark this tool if you regularly work with energy (nutrition labels, utility bills, engineering specs).
Remember: 1 kilowatt-hour (one month's worth of typical home electricity use) = 3.6 million joules—a huge amount of energy.
For food, always check if the label says 'calories' (kcal, kilocalories) or 'calories' (rare in modern labels); nutritional data is always kilocalories.
Joules are SI standard; if in doubt, convert to joules first, then to your target unit.

Frequently asked questions

What is a joule?

A joule (J) is the SI unit of energy. One joule is the energy needed to apply 1 newton of force over 1 metre, or the heat released when 1 watt of power runs for 1 second. It is the standard in physics and engineering worldwide.

Are food 'calories' the same as the chemistry calorie?

No. Food labels list kilocalories (kcal or Cal with a capital C), equal to 1,000 small calories. A 100-calorie snack label means 100 kilocalories = 418,600 joules. Always check the label; modern nutrition facts use kilocalories.

How much energy is a kilowatt-hour?

1 kWh = 3.6 million joules (3.6 megajoules). This is how much energy a 1-kilowatt appliance (e.g. a typical kettle or microwave) uses in 1 hour. A typical home uses 10–30 kWh per day.

Why are BTU and foot-pounds still used?

BTU (British thermal unit) is standard in HVAC, heating, and cooling in North America and the UK; foot-pounds appear in mechanical engineering and older machinery specs. Both predate metric standards and remain embedded in industry codes and specifications.

What is an erg?

An erg is a small unit of energy in the centimetre–gram–second (CGS) system: 1 erg = 1 dyne-centimetre = 0.0000001 joules. It is rarely used today but appears in older physics texts and astronomy calculations.

Can I convert energy to power with this tool?

No. Energy and power are different: energy is measured in joules or kWh; power is measured in watts or kilowatts. To get power, you divide energy by time (power = energy ÷ time). Use a power converter for watts, kilowatts, and similar units.