Convert Fahrenheit to Reaumur in seconds

Ever tried reading a 19th century European science paper or adjusting a Swiss cheese recipe only to find temperatures in Reaumur? That moment when you realize your thermometer only shows Fahrenheit? Let’s bridge that 250-year gap between these two scales. Whether you’re a history buff, a culinary enthusiast, or just love unit conversions, this guide turns Fahrenheit-to-Reaumur calculations from head-scratching to second nature.

Units explained

What is a fahrenheit (°F)?

• Description: The Fahrenheit scale was developed in 1724 by Daniel Gabriel Fahrenheit. It’s primarily used in the United States for weather reports, cooking, and medical settings.
• Symbol: °F
• Common uses: Oven temperatures, weather forecasts, body temperature measurements in the US.
• Definition: Originally based on a mixture of ice, water, and ammonium chloride. Today, it’s officially defined by the freezing (32°F) and boiling (212°F) points of water at 1 atmosphere pressure.

What is a reaumur (°Ré)?

• Description: Created by René Antoine Ferchault de Réaumur in 1730, this scale survives in niche applications despite being largely replaced by Celsius.
• Symbol: °Ré
• Common uses: Traditional cheese production, some European industrial processes, historical temperature records.
• Definition: Sets the freezing point of water at 0°Ré and boiling point at 80°Ré, creating 80 equal divisions between these two points.

Conversion formula

The mathematical relationship between these two scales is straightforward once you break it down:

°Ré = (°F - 32) × 4/9

To convert back:

°F = (°Ré × 9/4) + 32

Example calculations

1. Converting room temperature:
   68°F → (68 - 32) × 4/9 = 36 × 4/9 = 16°Ré
   Perfect for understanding European room temp specifications in older buildings.
2. Freezing point verification:
   32°F → (32 - 32) × 4/9 = 0°Ré
   Confirms water’s freezing point aligns perfectly between the scales.

Conversion tables

Fahrenheit to Reaumur

Reaumur to Fahrenheit

Historical background

The Fahrenheit and Reaumur scales emerged within six years of each other during the early 18th century’s measurement revolution. Fahrenheit’s mercury thermometer (1714) provided more consistent readings than alcohol thermometers, while Réaumur’s 1730 scale became popular in scientific circles for its decimal-like 80-degree boiling point. Interestingly, both inventors corresponded about thermal expansion. Though they probably never imagined we’d still be converting between their scales three centuries later.

A little known fact: Réaumur’s original work actually used alcohol thermometers marked from 0 to 1000 degrees! The 0-80 scale came later as a simplified version. Meanwhile, Fahrenheit’s “96 degrees” body temperature standard (later adjusted to 98.6°F) shows how these scales evolved through practical use rather than pure theory.

Interesting facts?

1. Cheese connection: Many Alpine cheesemakers still use Reaumur because traditional recipes specify fermentation temperatures in 2°Ré increments.
2. Alcohol advantage: The Reaumur scale’s 80-degree range made it popular for monitoring distillation processes in 18th-century Europe.
3. Russian resilience: Some Soviet-era industrial equipment used Reaumur until the 1990s, causing occasional conversion headaches during modernization.
4. Fahrenheit’s fix: The original Fahrenheit scale had water freezing at 32°F because that was the lowest temperature Fahrenheit could reliably reproduce using ice-salt mixtures.
5. Thermometer wars: In the 1740s, Fahrenheit and Reaumur supporters engaged in heated debates about which scale provided better precision for scientific work.

FAQ