Convert Degrees Reaumur to Degrees Fahrenheit (Interval)
Degree Reaumur (°r) to Degree Fahrenheit (°F) temperature INTERVAL conversion — enter any change in temperature below, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 °r = 2.25 °F
A 1 Degree Reaumur change = a 2.25 Degree Fahrenheit change
A 1 Degree Fahrenheit change = a 0.44444444 Degree Reaumur change
A 1 °r interval in every supported unit
Conversion chart: Degree Reaumur to Degrees Fahrenheit
Conversion table
| Degree Reaumur (°r) | Degree Fahrenheit (°F) |
|---|---|
| 0.01 °r | 0.0225 °F |
| 0.1 °r | 0.225 °F |
| 1 °r | 2.25 °F |
| 2 °r | 4.5 °F |
| 3 °r | 6.75 °F |
| 5 °r | 11.25 °F |
| 10 °r | 22.5 °F |
| 20 °r | 45 °F |
| 50 °r | 112.5 °F |
| 100 °r | 225 °F |
| 1000 °r | 2250 °F |
Degree Reaumur (°r)
Definition: A largely historical temperature interval unit — the Reaumur scale placed 80 degrees between water's freezing and boiling points, making one Reaumur degree of change 1.25 times the size of a Celsius or Kelvin degree.
History: Devised by French scientist Rene Antoine Ferchault de Reaumur in 1730, it was widely used across continental Europe, particularly in France, Germany, and Russia, before the Celsius scale displaced it in the 19th and 20th centuries.
Current use: Now largely obsolete outside of historical scientific texts and a handful of traditional food-processing and dairy contexts in parts of Europe that still reference Reaumur-scale equipment settings.
Degree Fahrenheit (°F)
Definition: A US customary temperature interval unit — because the Fahrenheit scale packs 180 degrees between water's freezing and boiling points (versus Celsius's 100), one Fahrenheit degree of change is smaller than one Celsius or Kelvin degree of change, by a factor of 5/9.
History: Devised by Daniel Gabriel Fahrenheit in the early 18th century using a brine freezing point and (approximately) human body temperature as reference marks, predating the Celsius scale by decades.
Current use: Still the everyday interval unit in the United States for describing temperature swings — "the high will be 10°F warmer tomorrow" — in weather reports and everyday conversation.
Supported Units
| Unit | Symbol | 1 Unit Interval = Kelvin Interval |
|---|---|---|
| Kelvin | K | 1 K |
| Degree Celsius | °C | 1 K |
| Degree Fahrenheit | °F | 0.55555556 K |
| Degree Rankine | °R | 0.55555556 K |
| Degree Reaumur | °r | 1.25 K |
About These Parameters
- Value
- The SIZE of a temperature change (not a temperature reading) you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The scale your interval is currently measured in — for example, a 15°C rise measured in a lab report.
- To Unit
- The scale you want the interval converted into. Use the swap button to flip From and To instantly.
How Temperature Interval Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the kelvin interval — no offset, unlike absolute temperature:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Degree Reaumur → Degree Fahrenheit: multiply by 2.25. A 1 °r change × 2.25 = a 2.25 °F change.
Interval vs. Absolute Temperature
Converting an absolute reading from Celsius to Fahrenheit needs both a multiply and an add (°F = °C × 9/5 + 32), because the two scales' zero points don't line up. Converting an INTERVAL only needs the multiply — the +32 offset represents where the scale starts, and it cancels out completely when you're only asking how big a change is, not where it started or ended. That's the entire reason this page exists separately from the site's regular Temperature Converter.
Why Celsius and Kelvin Intervals Are Identical
Celsius and Kelvin use degrees of exactly the same size — the Celsius scale is simply the Kelvin scale shifted down by 273.15 so that 0°C lands on water's freezing point instead of absolute zero. Because the degree SIZE is identical, a 1 K temperature change and a 1°C temperature change are the same amount of thermal energy change, which is why science and engineering formulas often use ΔT in kelvin and ΔT in Celsius interchangeably.
Example
A furnace that heats up by 1 °r experiences a change of 2.25 °F — this is true whether the furnace started at room temperature or was already red-hot, since only the SIZE of the change matters, not the starting point.
Frequently Asked Questions
How many Degrees Fahrenheit are in 1 Degree Reaumur?
1 Degree Reaumur (°r) equals exactly 2.25 Degrees Fahrenheit (°F).
Why can't I just use the regular Temperature Converter for this?
The regular Temperature Converter is built for absolute readings and applies an offset (e.g. °F = °C × 9/5 + 32). If you fed a temperature CHANGE into that formula, the +32 offset would corrupt the result — a 10°C rise would incorrectly come out as 50°F instead of the correct 18°F rise. This page's units carry no offset, so intervals convert correctly.
Is a 1°C interval the same as a 1 K interval?
Yes, exactly. The Celsius and Kelvin scales use identically sized degrees; Celsius is just Kelvin shifted by a fixed 273.15 offset. Since an interval measures only the size of a change, that offset has no effect and the two scales' intervals are numerically identical.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying degree sizes (e.g. 1°F interval = exactly 5/9 K interval) — results are limited only by floating-point display precision, not by rounded conversion constants.