よく使われる単位換算
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原理・換算係数の根拠
Temperature scales are not all anchored at the same zero point. Celsius and Fahrenheit use offset zero points, while Kelvin and Rankine are absolute scales.
For reliable conversion, rewrite the source value in Kelvin first, then convert from Kelvin to the target scale. This keeps both the scaling factor and offset explicit.
式と例
Formula: convert through Kelvin. For example, K = °C + 273.15 and °F = (K - 273.15) × 9/5 + 32.
Example: 25 °C = 298.15 K = 77 °F.
よくある誤り・注意点
- Do not treat absolute temperature conversions like pure multiplication; offsets matter.
- Temperature differences and absolute temperatures are not converted the same way in every formula context.
- Kelvin values cannot be negative in ordinary thermodynamic interpretation.
実用シーン
Temperature conversion is common in lab protocols, weather data, HVAC work, and material specifications where Celsius, Fahrenheit, and Kelvin are mixed.
Always check whether the value is an absolute temperature or a temperature difference before converting formulas in reports.
参考・データ出典
- BIPM — SI Brochure (kelvin)
- NIST SP 811 — Guide for the Use of SI
- ISO 80000 — Quantities and units, thermodynamics