Rankine to Fahrenheit Converter

1. Type the temperature in degrees Rankine, for example the answer of a gas law problem. It cannot be below 0.
2. Set the decimal places. The Fahrenheit answer has the same number of decimals as the Rankine input, so 2 places usually fit.
3. Read the Fahrenheit value, then Celsius and kelvin. To convert a whole table column, paste it into the bulk box.

In the text, deg R means degrees Rankine, deg F degrees Fahrenheit and deg C degrees Celsius. The tool prints the degree sign.

A Rankine to Fahrenheit conversion turns an absolute temperature into the reading a US thermometer would show. It is the last step after a calculation done in absolute units.

The Rankine scale starts at absolute zero and uses the Fahrenheit degree size. NASA calls it the absolute temperature of the Imperial system. Engineers work in Rankine inside gas law, combustion and heat-transfer formulas, because those formulas need a scale with a true zero.

People do not think in Rankine, though. A result of 549.67 deg R says little until it is written as 90 deg F. This conversion makes an answer readable. It lets you compare a result with a thermostat setting, a gauge limit or a weather report.

The conversion moves only the zero point. One Rankine degree and one Fahrenheit degree are the same size, so no factor of 1.8 or 5/9 appears.

The formula subtracts one constant, 459.67, from the Rankine value. That constant is the Rankine reading of 0 deg F.

1. Write down the Rankine value. Example: 1,000 deg R.
2. Subtract 459.67. Example: 1,000 - 459.67 = 540.33 deg F.
3. Check the sign. Any Rankine value below 459.67 gives a negative Fahrenheit answer, which is normal for cold conditions.

NIST SP 811 gives T/K = (T/deg R) / 1.8 and T/K = (t/deg F + 459.67) / 1.8. Both right-hand sides equal the same kelvin temperature. That makes deg R equal to deg F + 459.67, and deg F equal to deg R - 459.67. The subtraction is exact, so the answer keeps every decimal of the input.

A standard day, 518.67 deg R. 518.67 - 459.67 = 59 deg F. This is the sea-level temperature in the NASA standard atmosphere.

A round table value, 1,000 deg R. 1,000 - 459.67 = 540.33 deg F.

Hot gas at 2,000 deg R. 2,000 - 459.67 = 1,540.33 deg F.

The ice point, 491.67 deg R. 491.67 - 459.67 = 32 deg F.

A cold value, 400 deg R. 400 - 459.67 = -59.67 deg F. The Rankine number is positive, but the Fahrenheit reading is well below zero.

Absolute zero, 0 deg R. 0 - 459.67 = -459.67 deg F, the lowest Fahrenheit value that exists.

To go the other way, open the Fahrenheit to Rankine converter in the related tools below, or switch the direction box above.

The math is one subtraction, yet these four points decide whether the answer is right for your task.

The Offset Used Upstream

A calculation that added 459.7 on the way in should subtract 459.7 on the way out. NASA writes its Imperial atmosphere model with T + 459.7. Mixing 459.7 in and 459.67 out shifts the final reading by 0.03 deg F.

Reading Versus Difference

A Rankine reading needs the offset. A Rankine difference does not. A table step of 100 deg R is a step of 100 deg F, not -359.67 deg F.

Rounding in the Rankine Data

A table value given to the nearest whole deg R carries up to 0.5 deg R of rounding. The Fahrenheit answer carries the same 0.5 deg F. Extra decimals in the display do not remove that doubt.

Whether the Value Is Really Rankine

Kelvin and Rankine are both absolute, so a kelvin number can hide in a Rankine column. 300 K read as 300 deg R gives -159.67 deg F, while the true value is 80.33 deg F. For kelvin data, use the kelvin to Fahrenheit converter.

Both conversions start from an absolute scale and end at Fahrenheit. Rankine needs one subtraction, while kelvin needs a multiplication first.

The table shows why US engineering work stays in Rankine. One subtraction returns a familiar reading. A result in SI units takes the kelvin route, and the Fahrenheit to kelvin converter covers the opposite direction of that route.

Finishing a Gas Law Problem

Gas law math runs in absolute temperature. Suppose a sealed tank starts at 529.67 deg R and its absolute pressure rises by 10 percent. The new temperature is 529.67 x 1.10 = 582.64 deg R. Subtracting 459.67 gives 122.97 deg F, a number you can compare with a gauge.

Reading US Property Tables

Gas tables in English units list temperature in deg R. An entry at 1,260 deg R is 800.33 deg F. Pasting the table column into the bulk box converts every row at once.

Checking a Heat Capacity Unit

NIST lists Btu per pound degree Fahrenheit and Btu per pound degree Rankine with the same conversion factor. That is because the two degrees are the same size. Only temperature readings need the 459.67 shift, never per-degree units.

When the final report is metric, the Fahrenheit to Celsius converter takes the Fahrenheit reading one step further.

Exact values from deg F = deg R - 459.67, with Celsius rounded to 2 decimals for reference.

Whole Rankine values of 500 and above end in .33 in Fahrenheit, as in 500 - 459.67 = 40.33. Whole Fahrenheit values of zero and above end in .67 in Rankine.

1. Subtracting 491.67

491.67 deg R is the ice point and belongs to the Celsius formula. Using it here returns an answer exactly 32 degrees too low. For 1,000 deg R it gives 508.33 in place of 540.33 deg F.

2. Multiplying by 5/9 or Dividing by 1.8

That gives kelvin. 1,000 / 1.8 = 555.56 is the kelvin value, not a Fahrenheit reading.

3. Subtracting 273.15

273.15 is a kelvin offset. 1,000 - 273.15 = 726.85 matches no scale for this temperature.

4. Adding in Place of Subtracting

The Fahrenheit number is always smaller than the Rankine number. An answer larger than the input means the sign was flipped.

5. Applying the Offset to a Temperature Change

A 50 deg R rise is a 50 deg F rise. Subtracting 459.67 from a difference gives nonsense.

6. Treating a Negative Answer as an Error

Values between 0 and 459.67 deg R are real temperatures below 0 deg F. Only a negative Rankine input is impossible.

The conversion is exact, because 459.67 follows from defined constants. The display rounds only to the decimals you pick.

500 deg R is 40.33 deg F. Subtract 459.67 from the Rankine value.

It is 459.67 deg R. Rankine values above 459.67 give positive Fahrenheit readings, and values below it give negative ones.

600 deg R is 140.33 deg F. That is 60.18 deg C and 333.33 K.

Subtracting 460 is a common mental shortcut. It reads 0.33 deg F low, so use 459.67 for anything you report or reuse.

The Rankine value was below 459.67. That is a real temperature colder than 0 deg F, not an error.

No. The degree size is the same, but the zero differs. Rankine starts at absolute zero, while 0 deg F sits 459.67 degrees above it.

Leave the number unchanged. A 36 deg R difference is a 36 deg F difference, with no offset.

Use =A2-459.67 with the Rankine value in A2. Fill the formula down to convert a whole column.

Subtract 491.67 and divide by 1.8. The tool shows the Celsius value beside the Fahrenheit answer.

No. The page does the math locally. The Save button writes only to your own browser, and Clear removes it.

• Temperature conversion relations for Rankine, Fahrenheit and kelvin (NIST SP 811, Appendix B.9).
• Per-degree Fahrenheit and per-degree Rankine units share the same factors (NIST SP 811, Appendix B.8).
• The kelvin, absolute zero and Celsius temperature (NIST SP 330, The International System of Units, section 2).
• Rankine as the absolute temperature of the Imperial system (NASA Glenn Research Center, Equation of State).
• Imperial standard atmosphere: 59 deg F at sea level, written with T + 459.7 (NASA Glenn Research Center, Earth Atmosphere Model).