Temperature Conversion Calculator: °C, °F, K and °R

Enter a temperature, pick the scale it is in and the scale you want. The result comes with the formula used and the reading on all four scales.

Runs in your browserFree, no sign-upLast reviewed October 8, 2026

Result

33.8 °F

Conversion details

Input: 1 °C; Celsius (°C)
Formula: °F = °C × 9/5 + 32
Rounded: 33.8 °F

Same value in every unit

Unit	Value
Celsius (°C)	1 °C
Fahrenheit (°F)	33.8 °F
Kelvin (K)	274.15 K
Rankine (°R)	493.47 °R

Quick answers

How do I convert Celsius to Fahrenheit?: Multiply by 9/5 (1.8) and add 32. 20 °C × 1.8 = 36, plus 32 is 68 °F. 18.9 °C is 66.02 °F and 100 °C is 212 °F.
How do I convert Fahrenheit to Celsius?: Subtract 32, then multiply by 5/9. 350 °F minus 32 is 318, times 5/9 is 176.67 °C. 98.6 °F is 37 °C and 32 °F is 0 °C.
How do I convert Celsius to Kelvin?: Add 273.15. 25 °C is 298.15 K and 0 °C is 273.15 K. To go from Kelvin to Celsius, subtract 273.15, so 300 K is 26.85 °C.
At what temperature are Celsius and Fahrenheit equal?: At -40. Minus 40 °C and minus 40 °F are the same temperature, which is 233.15 K. It is the only point where the two scales cross.
What is absolute zero in Celsius and Fahrenheit?: Absolute zero is 0 K, which is -273.15 °C and -459.67 °F. It is also 0 °R, because Rankine starts at absolute zero like Kelvin.
How do I convert a temperature difference from Celsius to Fahrenheit?: Multiply by 1.8 and do not add 32. A rise of 10 °C is a rise of 18 °F. The offset applies only to readings on the scale, not to the gap between two readings.

About Temperature Converter

This tool does temperature conversion between Celsius, Fahrenheit, Kelvin and Rankine in any direction. Type a reading, choose From and To, and it returns the answer, the formula for that pair (for example °F = °C × 9/5 + 32) and a table showing the same temperature on all four scales. So 20 °C gives 68 °F, 293.15 K and 527.67 °R in one go. Unlike length or weight, temperature scales do not share a zero point, so most conversions need an offset as well as a multiplier. The offset is easy to drop when working by hand, which is why the formula is displayed each time.

Temperature conversion formulas for all 12 pairs

These are the formulas the tool applies and displays. The last column is what each one gives for an input of 100, rounded to two decimal places.

From	To	Formula	100 becomes
Celsius	Fahrenheit	°F = °C × 9/5 + 32	212 °F
Celsius	Kelvin	K = °C + 273.15	373.15 K
Celsius	Rankine	°R = (°C + 273.15) × 9/5	671.67 °R
Fahrenheit	Celsius	°C = (°F − 32) × 5/9	37.78 °C
Fahrenheit	Kelvin	K = (°F − 32) × 5/9 + 273.15	310.93 K
Fahrenheit	Rankine	°R = °F + 459.67	559.67 °R
Kelvin	Celsius	°C = K − 273.15	-173.15 °C
Kelvin	Fahrenheit	°F = (K − 273.15) × 9/5 + 32	-279.67 °F
Kelvin	Rankine	°R = K × 9/5	180 °R
Rankine	Celsius	°C = (°R − 491.67) × 5/9	-217.59 °C
Rankine	Fahrenheit	°F = °R − 459.67	-359.67 °F
Rankine	Kelvin	K = °R × 5/9	55.56 K

Only Kelvin to Rankine and back are a plain multiplication, because both scales start at absolute zero.

Celsius to Fahrenheit and Kelvin chart

Everyday temperatures from deep cold to boiling water.

Celsius	Fahrenheit	Kelvin	Rankine
-40 °C	-40 °F	233.15 K	419.67 °R
-18 °C	-0.4 °F	255.15 K	459.27 °R
-10 °C	14 °F	263.15 K	473.67 °R
0 °C	32 °F	273.15 K	491.67 °R
4 °C	39.2 °F	277.15 K	498.87 °R
10 °C	50 °F	283.15 K	509.67 °R
15 °C	59 °F	288.15 K	518.67 °R
20 °C	68 °F	293.15 K	527.67 °R
25 °C	77 °F	298.15 K	536.67 °R
30 °C	86 °F	303.15 K	545.67 °R
37 °C	98.6 °F	310.15 K	558.27 °R
38 °C	100.4 °F	311.15 K	560.07 °R
40 °C	104 °F	313.15 K	563.67 °R
100 °C	212 °F	373.15 K	671.67 °R

Oven temperatures: Fahrenheit to Celsius

Exact conversions of common US oven settings. Recipes and oven dials usually round the Celsius figure to the nearest 10.

Fahrenheit	Celsius (exact)	Typical dial setting
250 °F	121.11 °C	120 °C
275 °F	135 °C	140 °C
300 °F	148.89 °C	150 °C
325 °F	162.78 °C	160 °C
350 °F	176.67 °C	180 °C
375 °F	190.56 °C	190 °C
400 °F	204.44 °C	200 °C
425 °F	218.33 °C	220 °C
450 °F	232.22 °C	230 °C
475 °F	246.11 °C	240 °C
500 °F	260 °C	260 °C

The dial settings are conventional roundings, not tool output. Going the other way, 180 °C is exactly 356 °F and 200 °C is 392 °F.

Temperature difference conversion is not the same as converting a reading

A temperature and a temperature difference convert differently. A reading of 10 °C is 50 °F, but a change of 10 °C is a change of 18 °F. The 32 in the Celsius to Fahrenheit formula moves the zero point; a difference between two readings has no zero point to move, so only the 9/5 scale factor applies.

The rule for intervals: a difference in °C or K, times 1.8, is the difference in °F or °R. A difference in °F or °R, divided by 1.8, is the difference in °C or K. One Celsius degree and one kelvin are the same size, and so are one Fahrenheit degree and one Rankine degree.

This tool converts readings, so entering a difference with From Celsius and To Fahrenheit adds 32 and gives the wrong answer. There is a workaround: set From to Kelvin (K) and To to Rankine (°R). That pair is a pure multiplication by 9/5, so 10 in gives 18 out, which is the Fahrenheit difference for a 10 °C change. Use Rankine to Kelvin for the reverse.

Worked temperature conversions

A weather reading

Value 18.9, From Celsius (°C), To Fahrenheit (°F)

66.02 °F, with Formula °F = °C × 9/5 + 32

The table also shows 292.05 K and 525.69 °R.

A hot oven in Celsius

Value 203, From Celsius (°C), To Fahrenheit (°F)

397.4 °F

Just under boiling, in Fahrenheit

Value 209, From Fahrenheit (°F), To Celsius (°C)

98.333333 °C (Rounded: 98.33 °C)

Room temperature for a gas law calculation

Value 25, From Celsius (°C), To Kelvin (K)

298.15 K, with Formula K = °C + 273.15

Zero Fahrenheit

Value 0, From Fahrenheit (°F), To Celsius (°C)

-17.777778 °C (Rounded: -17.78 °C)

Quick ways to estimate without a calculator

Celsius to Fahrenheit, exact: double the Celsius figure, subtract a tenth of that, then add 32. For 20 °C: 40 minus 4 is 36, plus 32 is 68 °F.
Celsius to Fahrenheit, rough: double it and add 30. 20 °C gives 70 °F, two degrees high.
Fahrenheit to Celsius, rough: subtract 30 and halve. 70 °F gives 20 °C, close to the true 21.11 °C.
Anchor points worth knowing: 0 °C is 32 °F, 10 °C is 50 °F, 20 °C is 68 °F, 30 °C is 86 °F and 37 °C is 98.6 °F.
Every 5 °C step is a 9 °F step, so you can count up or down from an anchor.

How to get your result

1
Type the reading into Value. Use a minus sign for temperatures below zero.
2
Set From to the scale the reading is on: Celsius (°C), Fahrenheit (°F), Kelvin (K) or Rankine (°R).
3
Set To to the scale you want.
4
Read Result. Under Conversion details, Formula shows the equation for that pair and Rounded gives two decimal places.
5
Check the Same value in every unit table for the reading on all four scales.

Common questions

What is the Rankine scale used for?

Rankine is an absolute scale with Fahrenheit-sized degrees: 0 °R is absolute zero and °R = °F + 459.67. It appears mainly in engineering thermodynamics done in US customary units. Water freezes at 491.67 °R and boils at 671.67 °R.

Why is Kelvin written without a degree symbol?

The kelvin is a unit in its own right rather than a degree on a scale, so the correct form is 300 K, not 300 °K. Celsius, Fahrenheit and Rankine keep the degree sign.

Does the converter stop me entering a temperature below absolute zero?

No. It applies the formula to whatever number you enter, so -300 °C returns -508 °F even though nothing can be colder than -273.15 °C. If a result on the Kelvin or Rankine row is negative, the input was not a physically possible temperature.

How many decimal places does it show?

Result shows up to six decimal places with trailing zeros removed, so 350 °F appears as 176.666667 °C. Rounded shows two decimal places, 176.67 °C.

Is centigrade the same as Celsius?

Yes. Centigrade is the older name for the same scale, with water freezing at 0 and boiling at 100 at standard atmospheric pressure. The name Celsius was adopted internationally in 1948.

What is normal body temperature in Celsius and Fahrenheit?

The figure usually quoted is 37 °C, which converts to exactly 98.6 °F, or 310.15 K. Actual body temperature varies between people and through the day.

What is 100 °F in Celsius?

100 °F is 37.78 °C. Going the other way, 100 °C is 212 °F, the boiling point of water at standard pressure.

Why can't I just multiply to convert temperatures?

Because the scales start in different places. Celsius puts zero at the freezing point of water, Fahrenheit puts it 32 degrees below that, and Kelvin and Rankine put it at absolute zero. A multiplier alone fixes the degree size but not the starting point.