Réaumur to Fahrenheit Converter

Convert whole, negative, or decimal Réaumur values to Fahrenheit and reverse the calculation from either field.

Temperature to convert
Converted temperature

How the converter works

Two offset horizontal temperature scales with different numbers of divisions

Enter degrees Réaumur to multiply by 9/4 and then add 32. The converter starts with 16 °Ré = 68 °F, accepts negative and decimal values, and can calculate backwards from the Fahrenheit field.

Scale first, offset second

tF=tR×94+32t_{\mathrm{F}}=t_{\mathrm{R}}\times\frac{9}{4}+32

One Réaumur degree spans 2.25 Fahrenheit degrees. The extra 32 aligns the different zero points: 0 °Ré corresponds to 32 °F.

For the reverse direction, subtract before multiplying: tR=(tF32)×49t_{\mathrm{R}}=(t_{\mathrm{F}}-32)\times\frac{4}{9}.

Checks for both parts of the formula

0 °Ré equals 32 °F. This checks the offset without any scaling.

16 °Ré equals 68 °F. Multiply 16 by 2.25 to get 36, then add 32.

80 °Ré equals 212 °F. The upper water reference offers a second familiar check.

Edit the side you know

Type Réaumur on the left or Fahrenheit on the right. The middle button swaps both values and scales; the selectors also include Celsius and kelvin.

A point or comma works as a decimal separator. Results keep at most two decimal places and remove trailing zeroes.

Do not omit the 32-degree offset

Multiplying by 9/4 alone converts the interval size but not the scale origin. For a Fahrenheit input, subtract 32 before applying 4/9.

The arithmetic is exact, while the original measurement may be rounded or uncertain. The converter changes scale readings and does not model pressure or instrument calibration.

Réaumur and Fahrenheit questions

The most common errors concern operation order and the offset.

What is the Réaumur-to-Fahrenheit formula?

Use °F = °Ré × 9/4 + 32.

What is 20 °Ré in Fahrenheit?

20 °Ré equals 77 °F.

How do I convert Fahrenheit back to Réaumur?

Subtract 32 from °F, then multiply by 4/9.

What does 0 °Ré equal?

0 °Ré equals 32 °F.

Can negative Réaumur values produce positive Fahrenheit?

Yes. For example, -8 °Ré equals 14 °F because the scales have different zero points.

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