Fahrenheit to Celsius

What is Fahrenheit?

Fahrenheit (symbol °F) is the temperature scale proposed by Daniel Gabriel Fahrenheit in 1724. Its zero was originally set by an ice-and-brine mixture, and 96° by human body temperature — values that have since been recalibrated. The modern Fahrenheit scale is defined by two anchor points: 32°F is the freezing point of water and 212°F is its boiling point at standard atmospheric pressure, giving a 180° span between them (versus 100° on Celsius, so each Fahrenheit degree is smaller). Fahrenheit is the everyday scale used in the United States, the Cayman Islands, Liberia and a few other territories for weather, US ovens, US thermostats and US medical thermometers.

What is Celsius?

Celsius (symbol °C) is the everyday temperature scale used in almost every country in the world. It was proposed by Swedish astronomer Anders Celsius in 1742, originally with 0° as the boiling point of water and 100° as the freezing point; the scale was inverted shortly afterwards to its modern form. On the modern Celsius scale, 0°C is the freezing point of water and 100°C is its boiling point at standard atmospheric pressure. The scale shares its degree size with kelvin (the SI base unit of temperature), so a one-degree Celsius change equals a one-kelvin change. Weather forecasts, oven dials, fridge thermostats, body-temperature thermometers and almost every laboratory in the world report in Celsius.

The conversion formula

C = (F − 32) × 5/9 — subtract 32, multiply by 0.5555…. The reverse is F = C × 9/5 + 32. A worked example: a US summer day at 85°F converts to (85 − 32) × 5/9 = 53 × 5/9 = 29.44°C. A US winter morning at 25°F is (25 − 32) × 5/9 = -7 × 5/9 = -3.89°C. A 350°F oven becomes (350 − 32) × 5/9 = 318 × 5/9 = 176.67°C (often rounded to 180°C in recipes). Because the coefficients are exact rational numbers, the conversion is mathematically precise — there is no accumulated rounding error from the formula itself.

Common reference values

A handful of conversions worth memorising:

• -40°F = -40°C — the only point where the two scales meet.
• 0°F ≈ -17.78°C — a cold US winter night.
• 32°F = 0°C — water freezes; ice point.
• 50°F = 10°C — a cool spring day.
• 68°F = 20°C — comfortable room temperature.
• 77°F = 25°C — warm summer day.
• 86°F = 30°C — hot summer day.
• 98.6°F = 37°C — typical human body temperature.
• 212°F = 100°C — water boils at sea level.
• 350°F ≈ 176.67°C — a common US baking temperature (≈ 180°C).

The reference table on the page widens this list and updates live as you change the input value.

People search for this conversion in many ways — the abbreviated “convert f to c”, the full “fahrenheit to celsius formula” looking for the equation itself, and very commonly the misspellings “farenheit to celcius” or “convert farenheit to celcius” — all refer to exactly the same conversion and the same formula C = (F − 32) × 5/9. Worked end-to-end at a familiar number: 100°F − 32 = 68, then 68 × 5/9 = 37.78°C (very close to normal human body temperature of 37°C).

Why people convert Fahrenheit to Celsius

Weather and travel. Someone outside the US reading a US weather site or a US-set thermostat needs Celsius. “85°F in Florida” becomes 29.4°C; “25°F overnight in Chicago” becomes -3.9°C. Travel apps and news sites often display only one scale, depending on locale.

Cooking and baking. US recipes quote oven temperatures in Fahrenheit (350°F, 400°F, 425°F); international recipes use Celsius (180°C, 200°C, 220°C). A small error matters: 425°F (218°C) versus 350°F (177°C) is the difference between roasting and slow-baking. US recipes from blogs and TV often need converting before they fit a metric oven dial.

Body temperature. US thermometers display Fahrenheit (98.6°F normal, 100.4°F low fever, 102°F+ high fever); most thermometers outside the US display Celsius (37°C normal, 38°C low fever, 39°C+ high fever). Converting from Fahrenheit to Celsius is routine for international parents and travellers comparing reading thresholds.

Industry and HVAC. US air-conditioning set points, US-spec laboratory equipment, US brewing temperatures and US-shipped 3D-printer profiles often need converting when used in a metric context — particularly for hardware bought from US retailers and operated abroad.

How to use this Fahrenheit to Celsius converter

1. Type your value in Fahrenheit into the input box. Negative values and decimals both work directly. The result in Celsius updates as you type — no Convert button.
2. The reference table below shows several common Fahrenheit values and their Celsius equivalents, rendered to the same precision as the live result.
3. To go the other way (Celsius → Fahrenheit) tap Swap or open the dedicated Celsius to Fahrenheit landing.
4. Tap the copy icon next to the result to put the Celsius value on your clipboard, ready to paste into a form or thermostat app.
5. For a quick rough mental conversion, subtract 30 from the Fahrenheit value and halve — accurate to within a couple of degrees over the everyday weather range.

Privacy

The conversion is a single arithmetic expression — it runs locally on your device with no network call. There are no analytics on the numbers you type, no server-side logging, and the page works the same way offline once it has loaded. Confirm in your browser’s Network panel if you want; the only requests you’ll see are the one-time page load.

Compatibility notes

The math works in every browser ever made — it’s a subtract, multiply, divide. Result formatting uses the modern Intl-based number formatting that ships in every browser released since 2017, so very large and very small results display in scientific notation rather than as a wall of zeroes.