Celsius to Fahrenheit Converter
Enter a temperature in Celsius, Fahrenheit, Kelvin, or Rankine and this converter instantly shows the equivalent on all four scales, with a step-by-step breakdown, a comfort-band gauge, and a reference table of everyday landmarks from absolute zero to a pizza oven.
Formula
Worked example
22 °C (a comfortable room): 22 × 9/5 + 32 = 71.6 °F. Kelvin: 22 + 273.15 = 295.15 K. Rankine: 295.15 × 9/5 = 531.27 °R.
How the conversion formulas work
The Celsius and Fahrenheit scales share two fixed points: water freezes at 0 °C / 32 °F and boils at 100 °C / 212 °F at standard pressure. The 100-degree Celsius span maps to 180 Fahrenheit degrees (212 minus 32), giving the 9/5 scaling factor. Fahrenheit is also offset by 32 degrees from Celsius at the freezing point, which is why the formula is °F = (°C × 9/5) + 32. Going the other way, °C = (°F - 32) × 5/9. Kelvin shares the same degree size as Celsius but places zero at absolute zero (-273.15 °C), so converting between them is just K = °C + 273.15, and no scaling is needed. Rankine is the absolute scale paired with Fahrenheit: it also starts at absolute zero but uses Fahrenheit-sized degrees, so °R = K × 9/5, or equivalently °R = °F + 459.67.
Everyday temperature landmarks
A few reference points make it easy to sanity-check any conversion. Water freezes at 0 °C / 32 °F. Normal body temperature is 37 °C / 98.6 °F. A comfortable room is roughly 20-22 °C / 68-72 °F. A hot summer day hits 35 °C / 95 °F. Water boils at 100 °C / 212 °F. Bread bakes around 190 °C / 374 °F, and a pizza oven runs at roughly 260 °C / 500 °F. The only temperature where Celsius and Fahrenheit share the same numerical value is -40 degrees, the crossover point where the scales meet. The reference table below lists these and more across all four scales.
Which scale to use and why
Celsius is the everyday standard in most of the world and in science. Fahrenheit remains common in the United States for weather, cooking, and body temperature. Kelvin is the SI base unit for temperature and is used throughout physics, chemistry, and astrophysics because absolute scales make thermodynamic equations simpler: a gas law written in Kelvin never produces a division by zero or a negative absolute temperature. Rankine serves the same purpose in US engineering disciplines, particularly aerospace and thermodynamics, where legacy references use Fahrenheit-based absolute temperatures. All four are exact linear transformations of each other, so no information is lost in conversion.
Quick mental-math shortcuts
For rough weather estimates, a popular shortcut is to subtract 30 from Fahrenheit and halve the result to get approximate Celsius (e.g. 70 °F: (70 - 30) / 2 = 20 °C, exact is 21.1 °C). Going from Celsius to Fahrenheit, double and add 30 (e.g. 20 °C: 20 × 2 + 30 = 70 °F, exact is 68 °F). These rules are accurate to within 2-3 degrees for everyday weather temperatures but should not be used for precise scientific or clinical work. For exact results use the formulas above or the calculator on this page.
Accuracy and edge cases
This converter uses the exact SI-defined formulas, so any imprecision in the displayed result comes only from rounding at display time (two decimal places shown). The physical lower limit is absolute zero (0 K, -273.15 °C, -459.67 °F, 0 °R): no colder temperature exists. The boiling and freezing points cited here assume standard atmospheric pressure (101.325 kPa); at altitude or elevated pressure, phase-transition temperatures shift. For ultra-high-precision laboratory work, the International Temperature Scale of 1990 (ITS-90) introduces small corrections above the level of these formulas, but for all everyday, cooking, weather, clinical, and engineering uses the standard linear conversions are fully sufficient.
Common temperature reference points
| Reference point | °C | °F | K | °R |
|---|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 | 0 |
| Dry ice (CO2 sublimates) | -78.5 | -109.3 | 194.65 | 350.37 |
| Water freezes | 0 | 32 | 273.15 | 491.67 |
| Cold day (severe) | -20 | -4 | 253.15 | 455.67 |
| Cold day (mild) | -5 | 23 | 268.15 | 482.67 |
| Room temperature | 20 | 68 | 293.15 | 527.67 |
| Normal body temperature | 37 | 98.6 | 310.15 | 558.27 |
| High fever | 40 | 104 | 313.15 | 563.67 |
| Water boils | 100 | 212 | 373.15 | 671.67 |
| Bread baking | 190 | 374 | 463.15 | 833.67 |
| Pizza oven | 260 | 500 | 533.15 | 959.67 |
| Sugar caramelises | 170 | 338 | 443.15 | 797.67 |
| -40 parity point | -40 | -40 | 233.15 | 419.67 |
Boiling and freezing points assume standard atmospheric pressure (101.325 kPa). Body temperature is the standard clinical approximation.
Frequently asked questions
What is 37 degrees Celsius in Fahrenheit?
37 °C equals exactly 98.6 °F using the formula (37 × 9/5) + 32. This is the standard clinical approximation for normal human body temperature, which is why it is one of the most commonly searched temperature conversions. Normal body temperature actually varies between about 36.1 and 37.2 °C (97 and 99 °F) throughout the day.
At what temperature are Celsius and Fahrenheit the same?
The two scales are numerically equal at exactly -40 degrees. That is, -40 °C = -40 °F. This happens because the Fahrenheit degree is 5/9 the size of a Celsius degree and the zero points are offset by exactly 32 °F. Solving °C = (°C × 9/5) + 32 for the crossover gives -40. Below -40 the Fahrenheit number is always less negative than the Celsius number; above -40 it is always larger.
What is absolute zero in all four temperature scales?
Absolute zero is 0 K = 0 °R = -273.15 °C = -459.67 °F. It is the theoretical lower bound of temperature, the point at which a system has the minimum thermodynamic energy and all molecular motion would stop. It has never been reached in practice, though experiments have cooled matter to within nanokelvins of it.
What is the Rankine scale and who uses it?
Rankine (°R) is an absolute temperature scale that uses Fahrenheit-sized degrees but starts at absolute zero, so 0 °R = 0 K = -459.67 °F. It is used primarily in US aerospace engineering, thermodynamics, and legacy steam-tables where calculations require an absolute scale but all other measurements are in Fahrenheit. For most everyday and international scientific work, Kelvin is preferred.
What is the boiling point of water in Fahrenheit?
Water boils at 212 °F (100 °C, 373.15 K) at standard atmospheric pressure (sea level, 101.325 kPa). At higher altitudes where air pressure is lower, water boils at a lower temperature: at 2,000 m elevation water boils around 93 °C (199 °F), and on top of Mount Everest (about 8,850 m) at roughly 70 °C (158 °F).
How do I quickly convert Celsius to Fahrenheit in my head?
A good mental shortcut for everyday weather temperatures is to double the Celsius value and add 30: for example, 25 °C becomes roughly 80 °F (exact: 77 °F). For the reverse, subtract 30 from the Fahrenheit value and halve it: 80 °F becomes roughly 25 °C (exact: 26.7 °C). These rules are accurate to within about 2-3 degrees for temperatures between -10 and 40 °C. For precision, use the exact formula (°F = °C × 9/5 + 32).
What cooking temperatures should I know in both scales?
Common oven temperatures: 180 °C = 356 °F (standard bake), 200 °C = 392 °F (roasting), 220 °C = 428 °F (high roast), 260 °C = 500 °F (pizza). Sugar caramelises at about 170-180 °C (338-356 °F). Candy hard-crack stage is around 150 °C (300 °F). When a recipe gives oven temperatures in one scale, use the reference table on this page for an exact conversion.