Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin instantly. Accurate temperature conversion tool.

Free to use. Runs in your browser.

Enter a temperature and select the unit to see conversions to all other scales.

Value

From

°F (Fahrenheit)

212.00 °F

K (Kelvin)

373.15 K

The Formulas (in Plain English)

Three temperature scales matter in everyday life. Celsius is what most of the world uses. Fahrenheit is the US holdout. Kelvin is for scientists. Here's how they connect:

°F = (°C × 9/5) + 32

Celsius to Fahrenheit

°C = (°F - 32) × 5/9

Fahrenheit to Celsius

K = °C + 273.15

Celsius to Kelvin

Mental math shortcut: To get a rough Fahrenheit from Celsius, double the number and add 30. So 20°C ≈ 70°F (actual: 68°F). Close enough for weather chat.

Temperature Cheat Sheet

Bookmark this, it covers the conversions people look up most:

Context	°C	°F	K
Absolute zero	-273.15	-459.67	0
Water freezes	0	32	273.15
Fridge temperature	3-5	37-41	276-278
Room temperature	20-22	68-72	293-295
Body temperature	37	98.6	310.15
Fever threshold	38	100.4	311.15
Moderate oven	180	356	453.15
Hot oven	220	428	493.15
Water boils	100	212	373.15
C and F are equal	-40	-40	233.15

Why Three Different Scales Exist

Fahrenheit (1724): Daniel Fahrenheit set 0° at the coldest temperature he could reliably create (a brine solution) and 96° at human body temperature. The scale stuck in English-speaking countries and the US never switched.

Celsius (1742): Anders Celsius designed a 0-100 scale anchored to water's freezing and boiling points. It's elegant, intuitive, and now used by most of the world. Originally his scale was inverted (100 for freezing, 0 for boiling), Linnaeus flipped it a year later.

Kelvin (1848): Lord Kelvin started at absolute zero, the point where molecular motion stops. It's the same degree size as Celsius, just shifted by 273.15. Scientists use it because you can't have negative energy, and Kelvin avoids negative temperatures that break equations.

Common Conversion Scenarios

Following a US recipe

American recipes use Fahrenheit. 350°F = 177°C (round to 180°C). 400°F = 204°C (round to 200°C). 425°F = 218°C (round to 220°C). For precise oven temperatures including Gas Mark, try our Oven Temperature Converter.

Reading US weather forecasts

US weather is in Fahrenheit. Quick guide: 50°F = 10°C (jacket weather), 70°F = 21°C (comfortable), 85°F = 29°C (warm), 100°F = 38°C (dangerously hot). If the forecast says "feels like 105°F", that's 40.5°C, stay inside.

Checking for a fever

A fever starts at 38°C / 100.4°F for adults. High fever is 39.5°C / 103°F. Seek medical help above 40°C / 104°F. If your thermometer shows Fahrenheit and you think in Celsius (or vice versa), use this converter for peace of mind.

Science homework or lab work

Lab reports typically use Kelvin or Celsius. Room temperature is 293-295K (20-22°C). Standard temperature and pressure (STP) is 273.15K (0°C). Remember: you can't have negative Kelvin in classical thermodynamics.

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How to use this tool

Enter a temperature value in the input field

Select the source unit (°C, °F, or K)

View instant conversions to all other temperature scales

Common uses

Converting weather forecasts between Celsius and Fahrenheit
Setting oven temperatures for international recipes
Converting scientific measurements to Kelvin
Understanding body temperature readings in different units

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Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5, then add 32. For example, 100°C = (100 × 9/5) + 32 = 212°F. A quick shortcut: double the Celsius value and add 30 for a rough estimate.

How do I convert Fahrenheit to Celsius?

Subtract 32, then multiply by 5/9. For example, 72°F = (72 − 32) × 5/9 = 22.2°C. This is the standard room temperature.

What is absolute zero?

Absolute zero is 0 K, −273.15°C, or −459.67°F, the lowest possible temperature where all molecular motion stops. Nothing can be colder than this.

When should I use Kelvin?

Kelvin is used in scientific contexts like physics, chemistry, and engineering. It starts at absolute zero and uses the same increment size as Celsius, so a 1°C change equals a 1 K change.

What temperature is the same in Celsius and Fahrenheit?

−40 degrees is the same in both scales. −40°C = −40°F. This is the only point where the two scales intersect.

What is normal body temperature?

Normal body temperature is about 37°C (98.6°F). However, it varies throughout the day and between individuals, anywhere from 36.1°C to 37.2°C is considered normal.

What oven temperature is 180°C in Fahrenheit?

180°C = 356°F, which is close to the common US oven setting of 350°F. Most baking recipes calling for 180°C can use 350°F.

What is room temperature in Celsius?

Room temperature is typically 20 to 22°C (68 to 72°F). Scientific standard room temperature is defined as 25°C (77°F).

Why does the US use Fahrenheit?

The US adopted Fahrenheit before the metric system became standard globally. Fahrenheit was designed so that 0° and 100° roughly bracketed everyday weather temperatures, making it intuitive for daily use.

What is water's boiling point at altitude?

At sea level, water boils at 100°C (212°F). At higher altitudes, it boils at lower temperatures, roughly 1°C less per 300 metres of elevation. At the top of Everest, water boils at about 71°C.

How do I convert Kelvin to Celsius?

Subtract 273.15. For example, 300 K = 300 − 273.15 = 26.85°C. To go the other way, add 273.15 to any Celsius temperature.

What is the Rankine scale?

Rankine is an absolute temperature scale using Fahrenheit-sized degrees. 0 °R = absolute zero. It's mainly used in some US engineering fields. To convert: °R = °F + 459.67.

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