Fast reference
TL;DR
Use joules as the SI anchor: 1 kWh = 3.6 MJ, 1 BTU is about 1055.06 J, and 1 thermochemical calorie equals 4.184 J.
Use for
Energy Conversion
Best next step
Check the table, then calculate
Reviewed
2026-07-04
Guide
Overview
A practical energy conversion chart explaining joules, kilowatt-hours, BTU and calories without mixing energy and power.
Use this table for common energy references. For utility bills, kWh is usually the practical unit; for SI calculations, joules are cleaner.
- Use the chart for fast checks.
- Use the linked calculator for custom values.
- Keep the unit definition clear before rounding.
- Record the source when values enter technical work.
Reference table
Energy conversion chart
Use this table for common energy references. For utility bills, kWh is usually the practical unit; for SI calculations, joules are cleaner.
| Unit | Equivalent in joules | Typical context |
|---|---|---|
| 1 J | 1 J | SI energy unit |
| 1 kWh | 3,600,000 J | electricity billing |
| 1 BTU | about 1055.06 J | heat energy |
| 1 cal | 4.184 J | thermochemical calorie |
| 1 kcal | 4184 J | food Calorie |
Workflow
How to use this reference
Energy conversion becomes safer when power and time are kept separate.
Step 1
Use J or kJ for engineering equations.
Step 2
Use kWh for electricity usage over time.
Step 3
Use BTU for heating and cooling references.
Step 4
Use kcal carefully when nutrition labels say Calories.
Quality check
Common mistakes to avoid
The most damaging error is treating kW and kWh as interchangeable.
FAQ
Common questions
How many joules are in 1 kWh?
1 kWh equals exactly 3,600,000 joules.
Is a food Calorie the same as a calorie?
A nutrition Calorie is usually a kilocalorie, equal to 1000 small calories.
Is BTU power or energy?
BTU is energy. BTU per hour is a power or heat-rate unit.
Reference trail
Sources
Reference sources checked on 2026-07-04.