Unit Converter

Continue in the tool

More pages for this tool

celsius to fahrenheit

Celsius to Fahrenheit

Enter the temperature in °C and see the value in °F instantly, with the exact formula behind the math: °F = °C × 9/5 + 32. It is not an approximation, it is the exact linear relationship between the two scales, fixed by the same reference points since the 18th century.

The formula and where it comes from

The formula °F = °C × 9/5 + 32 comes from the ratio between the two scales' reference spans: between water's freezing and boiling points at sea level, Celsius spans 100 degrees (0 °C to 100 °C) while Fahrenheit spans 180 degrees (32 °F to 212 °F). The ratio 180/100 simplifies exactly to 9/5, so multiplying by 9/5 is not an approximation, it is the exact proportion between the two scales.
Since 1954, the 10th General Conference on Weights and Measures (CGPM) redefined the Celsius scale from a single fixed point, water's triple point, set at exactly 273.16 K, instead of the two fixed points (freezing and boiling) used until then. That means °C = K − 273.15 by definition today, and the Fahrenheit formula is exact algebra on top of that value, not an approximate measurement.
Daniel Gabriel Fahrenheit proposed his scale in 1724, anchored to a mixture of ice, water and ammonium chloride (0 °F) and to an estimate of human body temperature near 96 °F; later adjustments to the fixed points left water boiling at 212 °F, a number that is not round. The most common conversion mistake is reversing the order of operations, adding 32 before multiplying by 9/5 instead of after, which produces a wrong result for any value other than 0 °C.

°C → °F examples

Freezing

Input: 0 °C
Expected output: 32 °F

Reference point fixed since the international adoption of both scales; equal to 273.15 K.

Body temperature

Input: 37 °C
Expected output: 98,6 °F

Standard reference value for the human body; the exact conversion lands right on 98.6 °F, with no extra rounding.

Boiling

Input: 100 °C
Expected output: 212 °F

Water's boiling point at sea level (1 atm); at high altitude water boils at a lower temperature, but the scale conversion itself stays the same.

Full tool FAQ

Which unit categories does the tool convert?

There are fourteen categories: length, mass, temperature, data, time, speed, area, pressure, volume, energy, power, angle, frequency and fuel economy. Each one holds several units, from nanometer to nautical mile, from bit to exbibyte, from pascal to atmosphere, and conversion only happens between units of the same kind, because turning meters into seconds makes no sense.

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Why multiply by 9/5 instead of 1.8?

9/5 and 1.8 are exactly the same number, the exact fraction for the 180-to-100 ratio between Fahrenheit and Celsius degrees over the same interval; writing it as a fraction makes clear no rounding is involved.

Is there a temperature where Celsius and Fahrenheit match?

Yes, -40 °C is exactly -40 °F, the only point where both scales read the same number; solving C × 9/5 + 32 = C confirms it is the only solution.

Does Kelvin use the same formula?

No. Kelvin is an absolute scale linked to Celsius by K = °C + 273.15, with no multiplication, while Fahrenheit needs both the 9/5 multiplication and the 32 offset.

Next steps

From	To
-40 °C	-40 °F
-10 °C	14 °F
0 °C	32 °F
10 °C	50 °F
20 °C	68 °F
25 °C	77 °F
30 °C	86 °F
37 °C	98.6 °F
100 °C	212 °F

From

-40 °C

-40 °F

-10 °C

14 °F

0 °C

32 °F

10 °C

50 °F

20 °C

68 °F

25 °C

77 °F

30 °C

86 °F

37 °C

98.6 °F

100 °C

212 °F

The formula and where it comes from

The formula °F = °C × 9/5 + 32 comes from the ratio between the two scales' reference spans: between water's freezing and boiling points at sea level, Celsius spans 100 degrees (0 °C to 100 °C) while Fahrenheit spans 180 degrees (32 °F to 212 °F). The ratio 180/100 simplifies exactly to 9/5, so multiplying by 9/5 is not an approximation, it is the exact proportion between the two scales.

Since 1954, the 10th General Conference on Weights and Measures (CGPM) redefined the Celsius scale from a single fixed point, water's triple point, set at exactly 273.16 K, instead of the two fixed points (freezing and boiling) used until then. That means °C = K − 273.15 by definition today, and the Fahrenheit formula is exact algebra on top of that value, not an approximate measurement.

Daniel Gabriel Fahrenheit proposed his scale in 1724, anchored to a mixture of ice, water and ammonium chloride (0 °F) and to an estimate of human body temperature near 96 °F; later adjustments to the fixed points left water boiling at 212 °F, a number that is not round. The most common conversion mistake is reversing the order of operations, adding 32 before multiplying by 9/5 instead of after, which produces a wrong result for any value other than 0 °C.

°C → °F examples

Freezing

Input: 0 °C
Expected output: 32 °F

Reference point fixed since the international adoption of both scales; equal to 273.15 K.

Body temperature

Input: 37 °C
Expected output: 98,6 °F

Standard reference value for the human body; the exact conversion lands right on 98.6 °F, with no extra rounding.

Boiling

Input: 100 °C
Expected output: 212 °F

Water's boiling point at sea level (1 atm); at high altitude water boils at a lower temperature, but the scale conversion itself stays the same.

Full tool FAQ

Which unit categories does the tool convert?

Can I see the value in every unit at the same time?

Why is converting temperature different from converting length?

What is the difference between MB and MiB (decimal vs binary)?

Why are L/100 km and km/L not just a different factor?

Can I type the conversion instead of using the selectors?

Is the data I type sent to any server?

How do I control rounding and scientific notation?

Frequently asked questions

Why multiply by 9/5 instead of 1.8?

Is there a temperature where Celsius and Fahrenheit match?

Yes, -40 °C is exactly -40 °F, the only point where both scales read the same number; solving C × 9/5 + 32 = C confirms it is the only solution.

Does Kelvin use the same formula?

No. Kelvin is an absolute scale linked to Celsius by K = °C + 273.15, with no multiplication, while Fahrenheit needs both the 9/5 multiplication and the 32 offset.