Can I mix °C and K in thermodynamic calculations?

For temperature differences (ΔT), 1°C = 1 K, so they're interchangeable. But for formulas requiring absolute temperature (ideal gas law PV=nRT, radiation laws, etc.), you must use K.

Where is Rankine (°R) used?

It's the absolute temperature scale based on Fahrenheit, where °R = °F + 459.67. Used in some US thermodynamics and aerospace formulas. It relates to Fahrenheit the same way Kelvin relates to Celsius.

Temperature Unit Conversion | Eng Unit Converter

Temperature Conversion Guide

Temperature measures the average kinetic energy of particles in a substance. Unlike most unit conversions that use simple multiplication, temperature conversion involves both scaling and offset, making it uniquely error-prone. Key formulas: °F = °C × 9/5 + 32, K = °C + 273.15, °R = °F + 459.67. For temperature differences only: ΔT 1°C = ΔT 1.8°F = ΔT 1 K. Temperature conversion appears constantly in heat transfer calculations, thermodynamics, material science (thermal expansion), HVAC design, and process control. Absolute scales (K and °R) are mandatory for radiation heat transfer (Stefan-Boltzmann law) and ideal gas law calculations. Critical pitfalls: using °C instead of K in absolute-temperature formulas, confusing temperature value conversion with temperature difference conversion (adding 32 to a ΔT is wrong), and writing °K instead of K (Kelvin has no degree symbol). The intersection at -40°C = -40°F is a useful sanity check.

! Temperature — Good to Know

Distinguish between temperature "value" and temperature "difference". ΔT 1°C = ΔT 1 K = ΔT 1.8°F, but 1°C ≠ 1 K (it's actually 274.15 K).
Kelvin does not use the degree (°) symbol. "K" is correct, not "°K".
-40°C = -40°F is the only point where the two scales intersect.

Temperature

Temperature Conversion Guide

! Temperature — Good to Know

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