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Free Temperature Converter — Celsius, Fahrenheit, Kelvin

November 3, 2026 · 3 min read · By the DollarWise team

How it works

Temperature is just a number on a scale — converting between Celsius, Fahrenheit and Kelvin takes two simple linear formulas. Enter any value, pick the unit it is in, and this converter instantly shows the equivalent in all three scales. It updates live as you type, and it rejects values below absolute zero (0 K / −273.15 °C / −459.67 °F), which are physically impossible.

Temperature Converter

Celsius, Fahrenheit and Kelvin — converted instantly, all three at once.

100% Free Forever No Sign-up No Credit Card Private — runs in your browser Unlimited Use

1 Enter a temperature

Results update live as you type or change the unit.

2 Quick reference

Water freezes at 0 °C = 32 °F = 273.15 K and boils at 100 °C = 212 °F = 373.15 K at standard atmospheric pressure. Normal human body temperature is about 37 °C = 98.6 °F = 310.15 K. Absolute zero is 0 K = −273.15 °C = −459.67 °F — nothing can be colder.

3 See all three conversions

🌡️ Converted temperatures

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Convert as often as you like — every calculation happens in your browser.

## How the math works All three scales are linear offsets of one another. Celsius and Fahrenheit differ by both a scale factor (9/5) and an offset (32), while Kelvin is just Celsius shifted by 273.15 with the same size degree: - **Celsius ↔ Fahrenheit:** °F = °C × 9/5 + 32  ·  °C = (°F − 32) × 5/9 - **Celsius ↔ Kelvin:** K = °C + 273.15  ·  °C = K − 273.15 To convert from Fahrenheit to Kelvin, first convert Fahrenheit to Celsius, then add 273.15. To go the other way, subtract 273.15 to get Celsius, then apply the Fahrenheit formula. The Kelvin scale has no negative values — 0 K is absolute zero, the theoretical lower limit of temperature. ## Everyday uses - **Cooking and baking:** convert an oven temperature from a US recipe (°F) to your Indian oven's Celsius dial, or vice versa. - **Weather and travel:** understand a forecast in an unfamiliar unit — 30 °C is a hot day (86 °F), −10 °C is a deep winter freeze (14 °F). - **Science and homework:** check lab readings or physics problems across Celsius and Kelvin, where many formulas (gas laws, thermodynamics) require absolute temperature in Kelvin. ## Frequently asked questions ### Why is Kelvin written without a degree symbol? Kelvin is an absolute thermodynamic scale, not a relative one, so its unit is the "kelvin" (symbol K, not °K). One kelvin is exactly the same size as one degree Celsius — the scales only differ by their zero point: 0 K = −273.15 °C. ### Why does water boil at 212 °F but 100 °C? The Fahrenheit scale sets water's freezing point at 32 °F and boiling point at 212 °F — a 180-degree span. Celsius sets freezing at 0 °C and boiling at 100 °C — a 100-degree span. That 180/100 = 9/5 ratio is exactly the conversion factor between the two scales. Both numbers assume standard atmospheric pressure at sea level. ### Is there a temperature where Celsius and Fahrenheit are equal? Yes — at −40 degrees: −40 °C = −40 °F. You can verify it by solving x = x × 9/5 + 32, which gives x = −40. Kelvin never equals either of them numerically in any physically valid range, since 0 K is already −273.15 °C.