Convert Rankine to Fahrenheit (°R → °F)

Temperature scales differ in both zero-point and degree size, so conversion uses a formula — not simple multiplication. Follow these steps to convert degrees Rankine to degrees Fahrenheit by hand.

1. 1
   Take your value in degrees Rankine

   Start with the number of degrees Rankine (°R) you want to convert.
2. 2
   Apply the formula

   Use the formula: °F = °R − 459.67
3. 3
   Read the result in degrees Fahrenheit

   The result is your value in degrees Fahrenheit (°F).

Temperature conversion uses an offset formula, not simple multiplication.

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

• ✗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• ✗Writing °R when Réaumur degree is meant — Réaumur is obsolete.

What is the Rankine?

The Rankine scale is the absolute version of Fahrenheit, named after Scottish engineer William John Macquorn Rankine (1820–1872). Like Kelvin, Rankine sets 0° at absolute zero, but uses Fahrenheit-sized degrees: 1°R = 1°F (in size, not in offset). Water freezes at 491.67°R and boils at 671.67°R at sea level. The scale is rarely used today except in some American engineering disciplines, particularly in older thermodynamics, refrigeration, and aerospace calculations where Fahrenheit is the working unit. The Rankine relates to Fahrenheit by °R = °F + 459.67 and to Kelvin by °R = K × 9/5. While Kelvin has largely replaced Rankine in modern science, Rankine retains a niche in certain US engineering textbooks and HVAC standards. Its main advantage is allowing absolute-temperature thermodynamic calculations within a Fahrenheit-based engineering context.

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

What is the Fahrenheit?

Fahrenheit is the everyday temperature scale in the United States, used for weather, cooking, body temperature, and HVAC settings. Proposed by German physicist Daniel Gabriel Fahrenheit in 1724, it set 0°F as the lowest temperature he could reliably reproduce (a brine-ice mixture) and 96°F as human body temperature. Modern definitions place water's freezing point at exactly 32°F and boiling at 212°F — making the freezing-to-boiling range exactly 180 degrees. The Fahrenheit scale was the international standard for English-speaking countries until the UK and Commonwealth nations switched to Celsius in the 1960s and 70s. Today the United States is the only major industrialized country still using Fahrenheit for weather. A comfortable room is 68–72°F, fever begins at 100.4°F, and Death Valley summer highs reach 120°F. Fahrenheit relates to Celsius by °C = (°F − 32) × 5/9.

• US daily weather and climate reports
• US cooking oven temperatures
• US medical thermometers