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Temperature Converter

Convert between Fahrenheit, Celsius, and Kelvin instantly. Type any value, the other units update in real time. No rounding errors, no sign-up required.

°F
°C
K

Common Reference Points (click to load)

Reference°C°FK
Absolute zero-273.15-459.670
Water freezes032273.15
Room temperature2271.6295.15
Body temperature3798.6310.15
Water boils100212373.15

Common Temperature References

Some temperatures come up constantly in everyday life. Use the reference table in the converter above to load any of these instantly, or refer to the values below.

Body temperature

37°C / 98.6°F / 310.15 K, normal average for adults.

Water boiling point

100°C / 212°F / 373.15 K, at sea-level pressure.

Water freezing point

0°C / 32°F / 273.15 K, the basis of the Celsius scale.

Absolute zero

-273.15°C / -459.67°F / 0 K, the lowest possible temperature.

Understanding Temperature Scales

Fahrenheit is the primary temperature scale used in the United States for everyday weather, cooking, and body temperature. It was defined with 32°F as the freezing point of water and 212°F as the boiling point, giving a 180-degree span between those two fixed points.

Celsius (formerly Centigrade) is the standard in most of the world and all scientific contexts outside the US. Its two anchor points, 0°C (freezing) and 100°C (boiling), make it intuitive for everyday use. Kelvin shares the same degree size as Celsius but starts at absolute zero (0 K = -273.15°C), making it the preferred unit in physics, chemistry, and engineering where negative temperatures are meaningless or inconvenient. Kelvin is one of the seven SI base units, as defined by the BIPM.

The Conversion Formulas Explained

Behind every field in the converter above is one of three linear formulas. Each one takes a value in one scale and returns the equivalent in another by applying a fixed multiplier and, in two of the three cases, a fixed offset. Understanding the formulas helps explain why some conversions round cleanly (Celsius to Kelvin) while others rarely land on a whole number (Fahrenheit to Celsius).

Fahrenheit and Celsius

°C = (°F − 32) × 5/9 · °F = (°C × 9/5) + 32

These two scales were both defined using two fixed reference points, but different ones. Fahrenheit originally used a brine mixture (0°F) and human body temperature (96°F) as anchors; Celsius uses water's freezing point (0°C) and boiling point (100°C). Because the intervals differ (180 Fahrenheit degrees vs. 100 Celsius degrees between freezing and boiling), the 9/5 ratio and the 32-degree offset are both needed to convert accurately.

Celsius and Kelvin

K = °C + 273.15 · °C = K − 273.15

Kelvin and Celsius share the exact same degree size, so converting between them is just addition or subtraction, no multiplication needed. The offset of 273.15 places 0 K at absolute zero, the point at which atoms have minimum vibrational motion, which corresponds to −273.15°C.

Fahrenheit and Kelvin (combined)

K = (°F − 32) × 5/9 + 273.15

There is no direct Fahrenheit-to-Kelvin constant. The tool above converts internally through Celsius: it takes whichever field you edit, resolves it to Celsius first, then derives the other two units from that single value. This avoids compounding rounding errors that can occur when chaining separate formulas.

Worked example

Take a summer day at 30°C. Celsius to Fahrenheit: (30 × 9/5) + 32 = 86°F. Celsius to Kelvin: 30 + 273.15 = 303.15 K. If instead you started from 86°F and worked backward, subtracting 32 gives 54, and 54 × 5/9 gives exactly 30°C again, confirming the two formulas are true inverses of each other.

Common Use Cases

Cooking and baking: US recipes list oven temperatures in Fahrenheit while most of the world uses Celsius. A recipe calling for 350°F converts to 177°C, a common source of ruined bakes when the wrong scale is assumed.
Weather and travel: Travelers moving between the US and Celsius-using countries can quickly translate a forecast, for example 25°C is a comfortable 77°F, while 0°C (freezing) is 32°F.
Health and medicine: Body temperature readings from digital thermometers sold in different countries may default to either scale. Converting 38.5°C to 101.3°F helps compare a fever reading against US-style medical guidance.
Science and engineering: Lab work, gas law calculations, and physics problems require Kelvin because it is an absolute scale with no negative values, which keeps formulas like the ideal gas law mathematically valid.
3D printing and manufacturing: Filament and nozzle temperature specs are usually given in Celsius internationally, while some US-market hardware documentation still lists Fahrenheit equivalents.
Accuracy note: The converter rounds displayed values to two decimal places for readability. For scientific work requiring more precision, use the raw formulas above directly, since repeated rounding across multiple conversions can introduce small cumulative errors.

Other Temperature Scales (Not Covered by This Tool)

Fahrenheit, Celsius, and Kelvin cover virtually every everyday and scientific use case, which is why this tool sticks to those three. Two older scales occasionally still appear in older engineering references and some European cooking or brewing literature: Rankine (°R = °F + 459.67), an absolute scale that uses Fahrenheit-sized degrees, and Réaumur (°Ré = °C × 4/5), historically used in parts of Europe for sugar syrup and cheese-making temperatures. Neither is in common use today.

It is also worth distinguishing raw air temperature, what this tool converts, from a "feels-like" temperature such as heat index or wind chill. Those figures factor in humidity or wind speed on top of the actual thermometer reading, so a converted value (say 32°C to 90°F) will not match a feels-like forecast, which might report the same air temperature as feeling several degrees warmer or colder.

Frequently Asked Questions

How do you convert Fahrenheit to Celsius?▾
Subtract 32 then multiply by 5/9. Example: 98.6°F = (98.6 - 32) × 5/9 = 37°C. This formula works for all temperatures including negatives.
How do you convert Celsius to Fahrenheit?▾
Multiply by 9/5 then add 32. Example: 100°C = (100 × 9/5) + 32 = 212°F. Used for everyday weather, cooking, and medical temperatures in the US.
What is Kelvin and how does it relate to Celsius?▾
Kelvin is the SI base unit of temperature. 0 K is absolute zero, the coldest possible temperature. To convert: K = °C + 273.15. So 0°C = 273.15 K, 100°C = 373.15 K. Kelvin is used in science and physics.
What is absolute zero in Fahrenheit?▾
Absolute zero is 0 K = -273.15°C = -459.67°F. It is the theoretical lowest possible temperature where all molecular motion stops.
What is body temperature in Celsius?▾
Normal human body temperature is 37°C (98.6°F). A fever is typically above 38°C (100.4°F). These values are averages, individual normal body temperature ranges from 36.1°C to 37.2°C (97°F to 99°F).
At what temperature does water boil?▾
Water boils at 100°C (212°F) at standard sea-level atmospheric pressure (1 atm). At higher altitudes, water boils at lower temperatures because atmospheric pressure is lower.
Is there a temperature where Fahrenheit and Celsius are equal?▾
Yes, at -40°. Both scales read -40 at that exact point (-40°C = -40°F). This is because the two scales converge at that value.
Does this converter account for wind chill or heat index?▾
No. This tool converts the raw air temperature reading between Fahrenheit, Celsius, and Kelvin. Wind chill and heat index are separate "feels-like" calculations that factor in wind speed or humidity on top of the actual temperature, so they require different inputs than a straight unit conversion.

By Toolember · Updated September 2026