Energy conversion starts with the joule
The joule is the SI coherent unit of energy. CalcOS relates every supported energy unit to joules, retains the governed factor internally, and rounds only the displayed result.
Equal dimensions do not make energy and torque interchangeable quantities. Torque values remain outside this converter even when their units can be algebraically expressed with newton meters.
Named energy definitions
| Unit | Joule relationship | Status |
|---|---|---|
| thermochemical calorie | 4.184 J | exact |
| International Table calorie | 4.1868 J | exact |
| thermochemical kilocalorie | 4,184 J | exact |
| BtuIT | ≈ 1,055.056 J | NIST published factor |
| Btuₜₕ | ≈ 1,054.350 J | NIST published factor |
| electronvolt | 1.602176634 × 10⁻¹⁹ J | exact |
| foot pound-force | 1.3558179483314 J | exact derived definition |
Calories must name their variant
A thermochemical calorie and an International Table calorie are not equal. A dietary “Calorie” conventionally means one kilocalorie; CalcOS exposes named kilocalorie units instead of guessing from capitalization.
Btu variants are not interchangeable
The International Table and thermochemical British thermal units use different factors. Their unit names and symbols remain distinct in the picker, result, and provenance relationship.
Energy is not power
Energy measures an amount transferred or stored. Power measures the rate of energy transfer. Converting between joules and watts requires a time duration, so watts do not appear in this converter.
Authoritative references: BIPM SI Brochure v4.01 and NIST SP 811 Appendix B.8.