Energy Converter
Convert energy across physics, electricity, food, heating, and mechanical work labels. The converter normalizes each unit into joules so the full table can compare kWh, kcal, Btu, eV, and foot-pounds in one place.
Base unit
joule
Supported units
9
Includes
kWh + Btu
Live converter
Energy conversion inputs
Convert household energy, food energy, thermal energy, mechanical work, and atomic-scale energy through joules.
Converted result
3,600,000 J
Input
1 kWh
Output unit
J
Base method
joules
Energy in every supported unit
| Unit | Converted value | Unit name | Note |
|---|---|---|---|
| J | 3,600,000 | Joules | SI derived unit of energy. |
| kJ | 3,600 | Kilojoules | 1,000 joules. |
| cal | 860,420.650096 | Thermochemical calories | Common small calorie. |
| kcal | 860.420650096 | Kilocalories | Food Calorie. |
| Wh | 1,000 | Watt-hours | Power over time. |
| kWh | 1 | Kilowatt-hours | Common electricity-bill unit. |
| Btu | 3,412.14163313 | British thermal units | Thermal energy unit. |
| eV | 2.24694326681 x 10^25 | Electronvolts | Atomic-scale energy unit. |
| ft lbf | 2,655,223.7374 | Foot-pounds force | Mechanical work unit. |
Base unit
joule
Supported units
9
Includes
kWh + Btu
Convert energy for electricity, heat, food, and work
Electricity comparisons
Convert watt-hours and kilowatt-hours into joules for usage and equipment notes.
Food and heat units
Compare calories, kilocalories, and Btu with joules without hiding the factor route.
Physics problems
Translate mechanical work, electronvolts, and SI energy values in one table.
Energy conversion formula
The converter normalizes every source value into joules, then divides by the joule factor for the target unit.
Working formulas
Base conversion
joules = value x joules per source unit
Joules provide the common route for all supported energy units.
Target value
target value = joules / joules per target unit
The joule value is scaled into the selected target unit.
Electricity relationship
1 kWh = 3,600,000 J
A kilowatt-hour is power sustained over time.
Symbols
- J - joule
- SI derived unit of energy.
- kWh - kilowatt-hour
- Energy from one kilowatt of power used for one hour.
Energy definitions, scale, and result context
This live converter recalculates an amount of energy for one entered value. It is different from a static reference chart and from the power converter: power is a rate, while every row here represents an accumulated amount of work, heat, or transferred energy.
Named units and selected definitions
The joule is the SI energy unit, equal to a newton metre of work. The page uses exact SI prefixes, 3,600 J per Wh, 3,600,000 J per kWh, the thermochemical calorie at 4.184 J, and the electronvolt relationship from the exact elementary-charge definition.
The Btu row uses the International Table value of 1,055.05585262 J. The kcal row is 4,184 J and represents the food Calorie; the separate cal row is the small thermochemical calorie. Keeping those labels explicit prevents thousandfold calorie mistakes.
Worked conversion: 2.5 kilowatt-hours
2.5 kWh x 3,600,000 J/kWh = 9,000,000 J = 9 MJ
This factor chain is exact. It converts an energy amount only; estimating cost would also require a tariff, and estimating delivered work could require an efficiency model.
Retain the definition and useful digits
The converter displays up to 12 significant digits and switches extreme magnitudes to scientific notation. That is useful for electronvolts and household energy on the same page, but the source measurement still determines defensible precision.
When copying a result, keep cal versus kcal, the Btu convention, and the time-bearing h in Wh or kWh. Do not shorten kWh to kW because that changes an amount of energy into a power rate.
Use this page for an energy amount. Move to the power converter when the source is a rate such as watts, horsepower, or Btu per hour.
Convert an energy-transfer rate with the power converterLimits to keep with the result
- The page does not estimate utility price, device efficiency, heat loss, or useful mechanical output.
- Food Calories belong in the kcal row; the cal row is one thousand times smaller.
- A value in joules or kWh cannot establish power unless a duration is also known.
Why a joule-based table helps
One route across domains
- Electricity, food, heat, mechanical work, and particle-scale energy use different labels.
- The joule route makes each conversion factor visible and repeatable.
- Very small and very large values are formatted to stay readable.
Useful for references
- The formula block shows how watt-hours, calories, Btu, and foot-pounds connect to joules.
- The table is easier to audit than a single isolated answer.
- Unit notes explain where each label is commonly used.
Useful for energy comparisons
Home energy checks
Translate watt-hours and kWh into joules for device and utility comparisons.
Food and thermal notes
Compare calories, kilocalories, and Btu without mixing food and physics labels.
Students and makers
Use one table for SI, mechanical, electrical, and atomic-scale energy examples.
How it works in three quick steps.
Enter the energy value
Type a value from a physics problem, utility bill, nutrition label, or equipment note.
Choose source and target units
Select joules, kilojoules, calories, kilocalories, watt-hours, kWh, Btu, electronvolts, or foot-pounds.
Review the joule table
Use the table to see how household, food, thermal, mechanical, and atomic-scale units compare.
Save energy conversions
Copy labeled results
Copy the selected conversion with source and target unit labels for recipes, vehicle notes, utility comparisons, or homework.
Print the comparison table
Print the full table when repeated conversions need to stay visible at a counter, desk, shop, lab, or classroom.
Keep the method nearby
Use the formula notes to confirm whether the converter used milliliters, km/L, joules, or watts as the base route.
Frequently Asked Questions
What is a joule?
Is a food Calorie the same as a calorie?
Why does 1 kWh equal 3,600,000 joules?
When should I use Btu instead of joules?
Why are electronvolt results so large or small?
Related practical converters
About this energy converter
Energy appears in different forms across everyday and technical work: electricity bills use kilowatt-hours, nutrition labels use kilocalories, HVAC documents use Btu, physics problems use joules, and atomic-scale examples often use electronvolts. A useful converter needs to make those contexts visible instead of treating the answer as a black box.
This page converts every supported unit through joules. That keeps the method stable and helps explain relationships such as 1 kWh = 3,600,000 J and 1 kcal = 4,184 J. The table is designed for quick checks and for audit-friendly notes where the unit label matters as much as the number.
Who maintains this page
Ownership and review
Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.
Methodology
Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.
Read the editorial methodologyDates and sources
Review dates change only after a substantive method or content check.
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