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.

Use °F = (°C × 9/5) + 32, °C = (°F - 32) × 5/9, and K = °C + 273.15. Kelvin values should never go below 0 K.

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 used for weather, ovens, and body temperature in the US. Kelvin is the absolute scale used in science and engineering. 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 maths 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.

Worked Formula Examples

Celsius to Fahrenheit

25°C × 9/5 + 32 = 77°F

Useful for weather and room temperature.

Fahrenheit to Celsius

(68°F - 32) × 5/9 = 20°C

Subtract 32 before multiplying.

Celsius to Kelvin

20°C + 273.15 = 293.15 K

Kelvin uses no degree symbol.

The Fahrenheit conversion has both a scale change and an offset. The Kelvin conversion has no scale change from Celsius, only the 273.15 offset.

Celsius and Kelvin Reference Table

Celsius is the everyday metric temperature scale. Kelvin is the absolute scientific scale. A change of 1°C is the same size as a change of 1 K.

Point	Celsius	Kelvin	Note
Absolute zero	-273.15°C	0 K	Lowest thermodynamic temperature
Water freezes	0°C	273.15 K	At standard pressure
Room temperature	20 to 22°C	293.15 to 295.15 K	Common indoor range
Water boils	100°C	373.15 K	At sea level standard pressure

Fahrenheit Reference Table

Fahrenheit remains common for US weather reports, domestic ovens, and many household thermometers. These anchor points make quick interpretation easier.

Fahrenheit	Celsius	Typical meaning
32°F	0°C	Water freezes
68°F	20°C	Cool room temperature
77°F	25°C	Warm room or lab reference temperature
98.6°F	37°C	Traditional body-temperature reference point
212°F	100°C	Water boils at sea level standard pressure

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 with a brine solution and 96° near human body temperature. The scale remained in use in several English-speaking countries before metrication and is still widely used in the US.

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

Kelvin (1848): Lord Kelvin started at absolute zero, the point where thermal motion reaches its lower bound. It uses the same increment size as Celsius, just shifted by 273.15. Scientists use it because absolute temperature avoids many negative-temperature problems in ordinary 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

Many health services use 38°C / 100.4°F as a fever threshold for adults. If a thermometer shows Fahrenheit and you think in Celsius, convert the reading before comparing it with the guidance from your local health service.

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.

Common Temperature Conversion Mistakes

Forgetting the 32-degree offset

Fahrenheit is not just Celsius multiplied by a ratio. Always add 32 when going from Celsius to Fahrenheit, and subtract 32 first when going back.

Using a degree sign with Kelvin

Write 293.15 K, not 293.15°K. Kelvin is the unit name and does not use the degree symbol.

Allowing negative Kelvin

Ordinary thermodynamic Kelvin values cannot go below 0 K. If a calculation returns negative Kelvin, the input or formula is wrong for this context.

Rounding oven conversions too tightly

Domestic ovens often step in 5°C, 10°C, 25°F, or gas-mark increments. Round to the setting your appliance can actually hold.

Ignoring altitude for boiling water

100°C / 212°F is the boiling point at sea level standard pressure. At higher altitude, water boils at a lower temperature.

Mixing air, oven, and internal temperatures

A weather forecast, oven setting, and internal food temperature may all use the same scale but measure different things. Keep the context attached to the number.

Related Tools

Oven Temperature Converter

Convert with Gas Mark and fan oven

Length Converter

Convert between metric and imperial

Weight Converter

Convert kg, lbs, stone, and more

BMI Calculator

Calculate your body mass index

Time Zone Converter

Convert times across the globe

Scientific Calculator

Scientific maths calculations

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
Checking lab, appliance, and travel temperatures across regions

Share this tool

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.

Results are for general informational purposes only and should be checked before use. They are not professional advice. See our Disclaimer and Terms of Service.