How to Convert Fahrenheit to Celsius
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value, then multiply by 5 and divide by 9. The formula is °C = (°F − 32) × 5/9. The converter above gives you the answer instantly, but the formula is straightforward: take away 32 first, then scale down by 5/9 (about 0.556).
The Fahrenheit to Celsius Formula
This is simply the Celsius-to-Fahrenheit formula reversed. Because water freezes at 32 °F, you subtract 32 to line the zero points up. And because each Fahrenheit degree is smaller than a Celsius degree, you multiply by 5/9 to shrink the number to the Celsius scale. Do those two steps and any Fahrenheit reading becomes its exact Celsius equivalent.
Worked Examples
A normal body temperature of 98.6 °F: 98.6 − 32 = 66.6, times 5/9 = 37 °C. A hot 90 °F day: 90 − 32 = 58, times 5/9 = 32.2 °C. Boiling water at 212 °F: 212 − 32 = 180, times 5/9 = 100 °C. Freezing at 32 °F is 0 °C, and 68 °F room temperature is a comfortable 20 °C.
Common Fahrenheit to Celsius Values
Quick reference: 50 °F is 10 °C, 70 °F is about 21 °C, 80 °F is about 27 °C, and 100 °F is about 38 °C. A fever of 100.4 °F is 38 °C, and a very hot 104 °F is 40 °C. These come up constantly when reading thermostats, weather apps, or appliance settings that use the other scale.
When You Need This Conversion
If you live in or travel to a country that uses Celsius, Fahrenheit readings from American sources need converting — and vice versa. Recipes, scientific data, weather forecasts, fridge and oven settings, and health readings all jump between scales. Converting Fahrenheit to Celsius lets you compare numbers on the same footing instead of guessing whether 85 °F is warm or cold (it is a pleasant 29 °C). The tool above keeps a running, exact answer so you never have to do the arithmetic under pressure.
Frequently Asked Questions
What is the formula for Fahrenheit to Celsius?
°C = (°F − 32) × 5/9. Subtract 32, then multiply by 5 and divide by 9.
What is 98.6 °F in Celsius?
98.6 °F equals 37 °C, normal body temperature.
What is 100 °F in Celsius?
100 °F is about 37.8 °C.
Cooking the Other Way
Converting oven temperatures from Fahrenheit to Celsius is just as common for cooks following American recipes on metric appliances. A 350 °F oven is about 177 °C (set to 180 °C), 375 °F is about 191 °C, 400 °F is about 204 °C, and 425 °F is about 218 °C. Most ovens use round numbers, so converting and then rounding to the nearest 10 degrees is the practical approach.
Body Temperature and Fevers
Health is another everyday use. Normal body temperature of 98.6 °F is 37 °C. A reading of 100.4 °F — the common threshold for a fever — is 38 °C, 102 °F is about 38.9 °C, and 104 °F is 40 °C, which warrants medical attention. If your thermometer or a medical form uses the scale you are less familiar with, converting removes any doubt about how serious a temperature really is.
Weather Anchors in Reverse
Useful reference points when reading Fahrenheit weather in Celsius terms: 32 °F is 0 °C (freezing), 50 °F is 10 °C, 68 °F is 20 °C (room temperature), 86 °F is 30 °C, and 95 °F is 35 °C. With a handful of these memorized you can quickly judge whether to grab a jacket, and the converter above fills in any exact value you need in between.
Fahrenheit Temperatures Explained
Putting common Fahrenheit readings into Celsius makes them easier to interpret, especially if you grew up with the metric scale. A bitterly cold 0 °F is about −18 °C, a freezing 32 °F is 0 °C, a cool 50 °F is 10 °C, a mild 60 °F is about 16 °C, a pleasant 72 °F (typical indoor thermostat setting) is about 22 °C, a warm 80 °F is about 27 °C, a hot 90 °F is about 32 °C, and a scorching 100 °F is about 38 °C. Once you can place these anchor points, any Fahrenheit forecast instantly makes sense in Celsius.
The conversion also matters in science labs, manufacturing, and HVAC work, where equipment and documentation may use either scale. Getting it exactly right — rather than rounding aggressively — can be the difference between a process running correctly and a costly error. For casual use, rounding to the nearest degree is fine; for technical work, keep a decimal place. Whatever the context, subtracting 32 and multiplying by 5/9 always gives the precise Celsius value, and the calculator above handles the arithmetic so you can focus on the result rather than the math.
One More Quick Check
If you ever want to sanity-check a conversion, remember that the two scales cross at −40° and that every 5 °C change equals a 9 °F change. So a 20-degree Fahrenheit swing is a little over 11 °C — useful when you only care about how much the temperature changed rather than the absolute reading.