Temperature Converter

What this converter does

A temperature converter is not a length converter with different labels. Celsius, Fahrenheit, and Kelvin do not share a zero. Doubling 10 °C does not give a meaningful 20 °C in another scale. This temperature converter uses the affine identities: °C = (°F − 32) × 5/9, °F = °C × 9/5 + 32, and K = °C + 273.15. It converts through Celsius internally and then out to the target scale.

Kelvin is an absolute scale. A value below 0 K is not a temperature on this page. A Celsius or Fahrenheit reading that would land below 0 K is rejected the same way. Negative Celsius is allowed: −40 °C is −40 °F, which is a real identity, not a bug.

Use this page for weather, cooking, or a lab note. It will not convert Rankine or Réaumur. It will not decide a “feels like” temperature. It is independent of the length and mass converters because those jobs are linear and this one is not.

How to use

1. Enter the reading. Scientific notation is accepted when it is a real number.
2. Choose From and To. Convert. Swap units exchanges the scales.
3. Example loads 0 °C to Fahrenheit, which is 32 °F.

Empty input is an error. Markup is not a temperature. Enter converts. Labels sit above the field.

Example

0 °C is 32 °F and 273.15 K. 100 °C is 212 °F and 373.15 K. −40 °C is −40 °F. 0 K is −273.15 °C. A typed −1 K is rejected.

0 °C = 32 °F = 273.15 K
100 °C = 212 °F
−40 °C = −40 °F

Limits

• Only Celsius, Fahrenheit, and Kelvin.
• Values whose magnitude exceeds 1e15 are refused.
• Floating-point display, then trimmed. 273.15 is the defined offset used here.
• The arithmetic stays in this browser. Nothing is uploaded.

Write the scale next to the number. “32” without °F is unfinished. If you needed a length or a mass, this is the wrong converter.

Boiling and freezing of water at standard pressure are the familiar anchors: 0 °C and 100 °C. This page does not adjust for altitude or a different barometer. A “room temperature” guess is not a conversion. Type the reading you have. Cooking charts that switch C and F mid-recipe are why people burn sugar; convert the number and keep the scale in the margin.

Body-temperature folklore (98.6 °F) is 37 °C on these formulas. The page will not tell you whether that is a medical fact. It will only turn the number you typed. Kelvin is common in science notes; if a paper says 298 K, that is about 24.85 °C, not “298 degrees.” Oven knobs that list both scales still need this check when a recipe only printed one. Swap units after a convert if you want to read the other way without retyping. Empty input stays an error after swap, so you cannot manufacture a temperature from a blank field. Scientific notation is accepted when it is a real number, the same rule as the other converters.