What is the Kelvin to Fahrenheit formula?

°F = K × 1.8 − 459.67. The longer route says the same thing: subtract 273.15 to get Celsius, multiply by 9/5, then add 32. Both give 80.33 °F for 300 K. Reversed, K = (°F + 459.67) / 1.8, so 100 °F is 310.927777778 K, 70 °F is 294.261111111 K and −40 °F is 233.15 K.

Worked example: what is 32 K in Fahrenheit?

−402.07 °F, because 32 × 1.8 is 57.6 and 57.6 − 459.67 is −402.07. The trap in that question is that 32 is a Fahrenheit landmark, not a Kelvin one: water freezes at 273.15 K, and that is the value which reads 32 °F. Other cold anchors convert the same way, with 77 K, where nitrogen boils, at −321.07 °F and 4 K, near where helium boils, at −452.47 °F.

What is 300 K in Fahrenheit and Celsius?

80.33 °F and 26.85 °C, and both are on screen at once: the headline carries Fahrenheit and the list underneath carries Celsius. Hotter figures follow the same line, with 500 K at 440.33 °F, 1,000 K at 1,340.33 °F and the 5,778 K usually quoted for the surface of the sun at 9,940.73 °F.

Why can I not just multiply Kelvin by a number?

Because the two scales start in different places, so a ratio alone turns 0 K into 0 °F when the honest answer is −459.67 °F. This converter holds every unit as a factor and an offset against the kelvin, so the Fahrenheit degree carries both its 5/9 size and its 459.67 shift, and the shift survives in either direction. The multiplication only works on differences: a rise of 10 K is a rise of 18 °F.

What is absolute zero in Fahrenheit?

−459.67 °F exactly, and 0 °R on the Rankine scale, which counts Fahrenheit-sized degrees from absolute zero. Type 0 into the From box and the headline reads −459.67. Rankine sits behind the Show 1 more switch in the row under the converter, where 255.372222222 K reads 459.67 °R and 300 K reads 540 °R.

Will it stop me entering a temperature below absolute zero?

No, it converts what you type: −100 K comes back as −639.67 °F. The table behind the page holds sizes and offsets rather than physics, so nothing in it knows that 0 K is the floor. A negative Kelvin figure is nearly always a typo or a number that was already in Celsius, and the page cannot tell you which of the two it is.

Why does typing the answer back in not land on a round number?

Because a repeating decimal was cut to twelve digits on the way out. 0 °F prints as 255.372222222 K, and typing that printed figure back gives −3.581135e-13 °F rather than a clean 0, since anything below 0.000001 is shown in exponential notation. That is the rounding you can see rather than an error in the arithmetic. The swap button saves the retyping, though it reverses the units and keeps the number you typed, so it converts that same figure in the new direction.

How precise is the answer?

Twelve significant digits, which sits inside what double-precision arithmetic carries and is enough to absorb the residue a chained conversion leaves behind. 273.15 K works out to 31.999999999999986 in binary floating point and prints as 32 °F, the answer you would write by hand, and 310.15 K prints 98.6 °F for the same reason.

Does anything I type leave my browser?

No. The scales ship with the page as constants and the arithmetic runs locally, with no account and nothing uploaded, so the converter keeps working with no network connection once the page has loaded.

Kelvin to Fahrenheit Calculator

Kelvin and Fahrenheit do not share a zero, so this conversion is not a multiplication: the degree is resized and the scale is shifted, and both steps have to happen. °F = K × 1.8 − 459.67, which is the same arithmetic as (K − 273.15) × 9/5 + 32. That gives the anchors worth checking any converter against: absolute zero, 0 K, is −459.67 °F, 273.15 K is 32 °F, 293.15 K is 68 °F, 310.15 K is 98.6 °F and 373.15 K is 212 °F, while the 300 K that physics papers round room temperature to is 80.33 °F. This page opens the converter with Kelvin in the From box and Fahrenheit in the To box, ahead of whatever pair you last used, answers as you type to twelve significant digits, and lists the same temperature in Celsius underneath, where 300 K is 26.85 °C, with Rankine behind the Show 1 more switch at 540 °R. Every unit in this converter is stored as a size and an offset against the kelvin, which is why a scale that starts somewhere else converts correctly instead of landing on the classic 0 K = 0 °F.

From

To-457.87

1 K in every temperature unit

Celsius°C
-272.15
Fahrenheit°F
-457.87

Common questions

What is the Kelvin to Fahrenheit formula?: °F = K × 1.8 − 459.67. The longer route says the same thing: subtract 273.15 to get Celsius, multiply by 9/5, then add 32. Both give 80.33 °F for 300 K. Reversed, K = (°F + 459.67) / 1.8, so 100 °F is 310.927777778 K, 70 °F is 294.261111111 K and −40 °F is 233.15 K.
Worked example: what is 32 K in Fahrenheit?: −402.07 °F, because 32 × 1.8 is 57.6 and 57.6 − 459.67 is −402.07. The trap in that question is that 32 is a Fahrenheit landmark, not a Kelvin one: water freezes at 273.15 K, and that is the value which reads 32 °F. Other cold anchors convert the same way, with 77 K, where nitrogen boils, at −321.07 °F and 4 K, near where helium boils, at −452.47 °F.
What is 300 K in Fahrenheit and Celsius?: 80.33 °F and 26.85 °C, and both are on screen at once: the headline carries Fahrenheit and the list underneath carries Celsius. Hotter figures follow the same line, with 500 K at 440.33 °F, 1,000 K at 1,340.33 °F and the 5,778 K usually quoted for the surface of the sun at 9,940.73 °F.
Why can I not just multiply Kelvin by a number?: Because the two scales start in different places, so a ratio alone turns 0 K into 0 °F when the honest answer is −459.67 °F. This converter holds every unit as a factor and an offset against the kelvin, so the Fahrenheit degree carries both its 5/9 size and its 459.67 shift, and the shift survives in either direction. The multiplication only works on differences: a rise of 10 K is a rise of 18 °F.
What is absolute zero in Fahrenheit?: −459.67 °F exactly, and 0 °R on the Rankine scale, which counts Fahrenheit-sized degrees from absolute zero. Type 0 into the From box and the headline reads −459.67. Rankine sits behind the Show 1 more switch in the row under the converter, where 255.372222222 K reads 459.67 °R and 300 K reads 540 °R.
Will it stop me entering a temperature below absolute zero?: No, it converts what you type: −100 K comes back as −639.67 °F. The table behind the page holds sizes and offsets rather than physics, so nothing in it knows that 0 K is the floor. A negative Kelvin figure is nearly always a typo or a number that was already in Celsius, and the page cannot tell you which of the two it is.
Why does typing the answer back in not land on a round number?: Because a repeating decimal was cut to twelve digits on the way out. 0 °F prints as 255.372222222 K, and typing that printed figure back gives −3.581135e-13 °F rather than a clean 0, since anything below 0.000001 is shown in exponential notation. That is the rounding you can see rather than an error in the arithmetic. The swap button saves the retyping, though it reverses the units and keeps the number you typed, so it converts that same figure in the new direction.
How precise is the answer?: Twelve significant digits, which sits inside what double-precision arithmetic carries and is enough to absorb the residue a chained conversion leaves behind. 273.15 K works out to 31.999999999999986 in binary floating point and prints as 32 °F, the answer you would write by hand, and 310.15 K prints 98.6 °F for the same reason.
Does anything I type leave my browser?: No. The scales ship with the page as constants and the arithmetic runs locally, with no account and nothing uploaded, so the converter keeps working with no network connection once the page has loaded.

Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.