What is a rankine?

Definition

The Rankine scale is an absolute scale whose degree size matches Fahrenheit. Zero °R is absolute zero (−459.67 °F). It is used in some US engineering thermodynamics — mainly aerospace, power plants and propulsion — where Fahrenheit-based calculations need an absolute reference.

Common uses

• ●US aerospace thermodynamics
• ●US steam-turbine and power-plant engineering
• ●Some US industrial combustion calculations

🌍 Real-world scale

Room temperature ≈ 527 °R. Water boils at 671.67 °R. US rocket-engine thermodynamics textbooks use Rankine.

Tips

• 💡°R = °F + 459.67.
• 💡°R = K × 9/5. Identical absolute-zero anchor, different degree size.
• 💡Rankine is essentially obsolete outside specific US engineering specialisms.

Common mistakes

• ⚠️Confusing Rankine with Réaumur (another historical scale).
• ⚠️Using Rankine outside US engineering contexts — nowhere else uses it.
• ⚠️Writing °R when Réaumur degree is meant — Réaumur is obsolete.

FAQ about the rankine