Temperature Converter

Unit Converters

Convert between Celsius, Fahrenheit, and Kelvin

Temperature is one of the few measurements where the scales don't just use different units — they use different zero points entirely. The United States reports weather in Fahrenheit while nearly every other country uses Celsius, and scientists rely on Kelvin, which starts at absolute zero rather than the freezing point of water. That means you can't just multiply to convert temperature; you need a formula that shifts the scale, not just resizes it.

Our temperature converter handles Celsius, Fahrenheit, and Kelvin instantly. Enter a value in any one scale and see the accurate equivalent in the other two — no memorizing formulas, no arithmetic mistakes on a number that matters, like a fever reading or an oven temperature.

Whether you're checking the weather forecast while traveling abroad, converting an oven temperature from a UK recipe, or working through a chemistry problem that requires Kelvin, this tool gives you a precise answer in seconds.

Why Temperature Converter Matters

Temperature conversion errors can be more than an inconvenience — they can be dangerous or expensive. Cooking is the most common flashpoint: a recipe calling for an oven at 200°C means 392°F, not 200°F, and using the wrong number can under-cook or burn a dish entirely. Travelers checking a forecast of 30°C need to know that's a hot 86°F day, not a cool one, to pack and plan appropriately.

Science and medicine depend on precise temperature conversion too. Kelvin is the standard unit in physics and chemistry because it starts at absolute zero (0 K = -273.15°C), making it essential for gas law calculations and lab work where Celsius or Fahrenheit would introduce negative numbers into equations that assume a true zero. Medically, understanding that a normal body temperature of 37°C equals 98.6°F matters for anyone reading a thermometer calibrated in the "wrong" scale, especially when monitoring a fever in a country that uses different units than what you grew up with.

The Temperature Converter Formula, Explained

°F = (°C × 9/5) + 32 | °C = (°F − 32) × 5/9 | K = °C + 273.15

Unlike length or weight, temperature scales have different zero points, so conversion requires addition/subtraction as well as multiplication. To convert Celsius to Fahrenheit: multiply by 9/5 (1.8), then add 32. To convert Fahrenheit to Celsius: subtract 32, then multiply by 5/9. To convert Celsius to Kelvin: simply add 273.15, since a Kelvin degree is the same size as a Celsius degree — only the starting point differs (Kelvin's zero is absolute zero, the coldest possible temperature). To convert Fahrenheit to Kelvin: first convert to Celsius, then add 273.15.

Key reference points: water freezes at 0°C / 32°F / 273.15 K, and boils at 100°C / 212°F / 373.15 K. Notably, -40° is the one temperature where Celsius and Fahrenheit read the same number.

How to Use the Temperature Converter: Step by Step

  1. Enter your temperature value

    Type the number you want to convert, such as 100 (Fahrenheit) or 37 (Celsius).

  2. Select the scale you're converting from

    Choose Celsius, Fahrenheit, or Kelvin as your starting unit.

  3. Select the scale you want to convert to

    Choose your target scale. The calculator instantly applies the correct formula and displays the result.

  4. Read your result

    The converted temperature appears immediately, rounded to a practical precision for weather, cooking, or science use.

Temperature Converter Examples: Real-World Scenarios

1

Checking a Fever Reading

A parent traveling abroad reads a thermometer showing 37°C on their child and wants to know if that's a fever in the Fahrenheit scale they grew up with.

Temperature:37°C

Calculation

F = (37 × 9/5) + 32 = 66.6 + 32 = 98.6°F

Result

37°C equals 98.6°F — normal body temperature, not a fever.

2

Converting a Weather Forecast

Someone sees a forecast high of 100°F for a trip to Arizona and wants to know the Celsius equivalent to understand how hot that really is.

Temperature:100°F

Calculation

C = (100 − 32) × 5/9 = 68 × 5/9 = 37.78°C

Result

100°F equals approximately 37.8°C — a very hot day.

3

Chemistry Lab Kelvin Conversion

A chemistry student needs to convert a room temperature reading of 25°C into Kelvin for a gas law calculation.

Temperature:25°C

Calculation

K = 25 + 273.15 = 298.15 K

Result

25°C equals 298.15 K, the value required for the ideal gas law formula.

Common Mistakes to Avoid

  • Treating temperature conversion like a simple multiplication (as with length or weight) — forgetting to add or subtract 32 when converting between Celsius and Fahrenheit produces a badly wrong answer.
  • Confusing a temperature difference with an absolute temperature — a change of 10°C equals a change of 18°F (not 50°F), since only the scale size, not the zero point, matters for differences.
  • Forgetting that Kelvin has no negative values in normal use — 0 K is absolute zero (-273.15°C), so a 'negative Kelvin' answer usually signals an input or formula error.

Tips & Tricks

  • Quick mental estimate for Celsius to Fahrenheit: double the Celsius value and add 30 — it's not exact, but it's close enough for everyday weather checks.
  • Remember -40° is the single point where Celsius and Fahrenheit are equal, a handy sanity check when verifying your own mental math.

Temperature conversion trips people up more than any other unit because the scales don't share a zero point. This converter applies the exact formulas instantly across Celsius, Fahrenheit, and Kelvin, whether you're reading a fever, checking the forecast abroad, or working a science problem. Pair it with our length converter and weight converter for a complete travel and cooking toolkit.

Temperature Converter — Frequently Asked Questions

Related Calculators

Authoritative References

External links open in a new tab. OmniCalc.us is not affiliated with these organisations.

Related Calculators