Convert Romer to Rankine easily.

Trying to convert 17th century Danish temperatures to aerospace engineering units sounds like something from a steampunk novel, doesn't it? Yet here we are, bridging the gap between Ole Rømer's vintage mercury thermometers and modern rocket science calculations. Whether you're restoring historical weather records or solving thermodynamic equations, understanding Romer to Rankine conversion reveals fascinating connections across centuries of measurement.

Unit definitions

What is a romer (°Rø)?

The Romer scale was invented by Danish astronomer Ole Christensen Rømer in 1701. It uses the freezing point of brine (7.5°Rø) and boiling water (60°Rø) as fixed points. While largely obsolete today, it played a crucial role in early thermometer development. You'll mostly encounter it in historical European scientific documents.

Symbol: °Rø
Common uses: 18th century temperature recording, early thermodynamics experiments
Definition: (Celsius × 21/40) + 7.5

What is a rankine (°R)?

The Rankine scale, named after Scottish engineer William John Macquorn Rankine (1820-1872), measures absolute temperature like Kelvin but uses Fahrenheit increments. Zero Rankine (0°R) equals absolute zero, making it valuable for engineering calculations requiring absolute temperature values.

Symbol: °R
Common uses: US aerospace systems, thermodynamic cycle analysis
Definition: Fahrenheit + 459.67

Conversion formula

The mathematical relationship between these scales is: °R = (°Rø - 7.5) × 24/7 + 491.67

This equation first converts Romer to Celsius equivalent, then adjusts to the Rankine scale's absolute zero offset.

Example calculations

1. Freezing point of water (7.5°Rø):
   (7.5 - 7.5) × 24/7 + 491.67 = 0 + 491.67 = 491.67°R
   Matches water's freezing point in Rankine
2. Boiling point of water (60°Rø):
   (60 - 7.5) × 24/7 + 491.67 = (52.5 × 3.4286) + 491.67 ≈ 180 + 491.67 = 671.67°R
   Aligns with water's boiling point at standard pressure

Conversion tables

Romer to Rankine

Rankine to Romer

From Copenhagen pubs to spacecraft engines

The story of these scales reads like a scientific buddy cop movie. Rømer's 1701 creation emerged from Copenhagen's bustling scientific community, where accurate temperature measurement was becoming crucial for weather tracking and beer brewing (yes, really). His scale used ammonium chloride brine's freezing point as a baseline because... well, 18th century scientists worked with what they had.

Fast forward 150 years to industrial Scotland. William Rankine needed absolute temperatures for steam engine efficiency calculations. By anchoring his scale to absolute zero using Fahrenheit degrees, he created a system that still benefit engineers today (who might convert historical European data while designing jet turbines).

Interesting facts

1. Fahrenheit based his famous scale on Rømer's work after visiting Copenhagen in 1708
2. The Rankine scale is required by NASA for certain propulsion system calculations
3. Only three countries still use Rankine regularly: USA, Liberia, and Myanmar
4. Rømer's original thermometer used red wine instead of mercury
5. At -135°Rø (-218°F), ethanol freezes - Rømer's wine thermometers would stop working in Arctic conditions

FAQ