Fahrenheit to Celsius Converter — Formula, Chart & Full Table

How to convert Fahrenheit to Celsius

Enter a Fahrenheit value in the field above and read the Celsius result instantly — or drag the ▲/▼ slider next to the thermometer, scroll your mouse wheel over it, or click any point on the thermometer scale. All inputs stay perfectly in sync because every indicator on the page is driven by the same single value. The converter also displays Kelvin, Rankine, and the popular (F − 30) ÷ 2 mental-math shortcut, so you can compare precise and approximate results side by side. Tap the swap icon to reverse the direction and convert Celsius back into Fahrenheit — the current result automatically becomes the new input.

Use the quick presets — absolute zero, freezing, room temperature, body temperature, fever, boiling, and oven heat — to see how the scales line up on the interactive thermometer and on the linear-relationship chart below the converter.

The Fahrenheit to Celsius formula (three equivalent forms)

°C = (°F − 32) × 5/9. That's the exact conversion. The three forms below are mathematically identical — pick whichever is easiest to remember:

All three come from the same underlying fact: one Celsius degree is 1.8 Fahrenheit degrees, and the two scales are offset by 32 degrees at water's freezing point.

Worked example: 70 °F to Celsius

1. Subtract 32: 70 − 32 = 38
2. Multiply by 5/9 (or divide by 1.8): 38 × 5/9 = 21.111…
3. Round to two decimals: 21.11 °C

The "easy way" — quick mental-math shortcut

Subtract 30 from Fahrenheit, then divide by 2. That gives a Celsius estimate you can do in your head. This shortcut, popularized by developer Chas Hollis on the thoughtbot blog, is accurate within 1–2 degrees for everyday weather temperatures:

For weather and clothing decisions the shortcut is more than good enough. For science, cooking, engineering, or medicine, always use the exact formula.

What is Fahrenheit? Origin and definition

Fahrenheit is a temperature scale where water freezes at 32 °F and boils at 212 °F at standard atmospheric pressure. It was proposed in 1724 by the German-Polish physicist Daniel Gabriel Fahrenheit, who also invented the modern mercury-in-glass thermometer in 1714 (Britannica).

Fahrenheit chose his reference points from three fixed temperatures: a brine of ice, water and ammonium chloride at 0 °F, the freezing point of pure water at 32 °F, and human body temperature at 96 °F (later refined to 98.6 °F). The 180-degree span between water's freezing and boiling points gave finer resolution than the systems that came before, which is why the scale caught on in English-speaking countries during the 18th century (Wikipedia).

What is Celsius? Origin and definition

Celsius is a temperature scale where water freezes at 0 °C and boils at 100 °C at 1 atmosphere of pressure. It was proposed in 1742 by the Swedish astronomer Anders Celsius. Curiously, Celsius's original scale was upside-down — he defined 0° as the boiling point of water and 100° as the freezing point. The scale was inverted to its modern form by Jean-Pierre Christin in 1743 (Wikipedia).

Celsius (originally "centigrade," meaning "hundred steps") is the metric world's standard temperature unit and part of the International System of Units by way of the Kelvin scale, which uses the same-sized degree but starts at absolute zero. Since 2019 the Celsius degree has been defined via the Boltzmann constant, tying it directly to fundamental physics rather than the properties of water.

Which countries use Fahrenheit vs Celsius?

Only five countries and territories still use Fahrenheit as their official everyday temperature scale: the United States, the Bahamas, the Cayman Islands, Liberia, and the U.S. territories such as Puerto Rico and Guam (World Population Review). Every other country reports weather forecasts, cooking temperatures and body temperature in Celsius. Even in Fahrenheit-using countries, science, medicine, and international commerce use Celsius or Kelvin, which is why a fast, accurate converter is a daily-use utility for millions of people.

Fahrenheit to Celsius conversion table (−50 °F to 1000 °F)

Key reference points are highlighted. Scroll to see the full range.

Oven and cooking temperature conversions

Recipes cross oceans, so oven temperatures often appear in a scale you didn't grow up with. Use this handy chef's reference:

Human body temperature — normal, fever and hypothermia

The traditional "normal" body temperature of 98.6 °F (37 °C) comes from a 19th-century study and is still widely quoted. Modern research from Stanford Medicine, however, places the true average closer to 97.9 °F (36.6 °C) — humans have measurably cooled since the 1860s (Stanford Medicine).

The Cleveland Clinic, Mayo Clinic and Harvard Health all define fever in adults as 100.4 °F (38 °C) or above, while normal daily variation of roughly 1 °F (0.5 °C) is expected between morning and late afternoon (Cleveland Clinic, Mayo Clinic).

Weather quick reference — what temperatures actually feel like

• Below 0 °F (−18 °C): Bitter cold. Frostbite possible on exposed skin within 30 minutes.
• 0 – 32 °F (−18 – 0 °C): Winter cold. Heavy coat, hat, gloves, and layers required.
• 32 – 50 °F (0 – 10 °C): Cold. Jacket or coat, long sleeves.
• 50 – 65 °F (10 – 18 °C): Cool. Sweater or light jacket weather.
• 65 – 75 °F (18 – 24 °C): Mild and comfortable — the classic "room temperature" range.
• 75 – 85 °F (24 – 29 °C): Warm summer day. T-shirt weather.
• 85 – 95 °F (29 – 35 °C): Hot. Hydration and shade become important.
• Above 95 °F (35 °C): Very hot. Heat-index warnings; limit strenuous outdoor activity.

Fahrenheit, Celsius, Kelvin and Rankine — how they relate

Four temperature scales are in common use, and they all measure the same physical quantity:

• Celsius (°C): Water freezes at 0, boils at 100. The everyday scale in most of the world.
• Fahrenheit (°F): Water freezes at 32, boils at 212. Used in the U.S. and a few smaller nations.
• Kelvin (K): Same degree size as Celsius, but starts at absolute zero (−273.15 °C). Used in science.
• Rankine (°R): Same degree size as Fahrenheit, but starts at absolute zero. Used in some U.S. engineering fields.

Frequently asked questions