Fahrenheit to Celsius Calculator
Convert a temperature in Fahrenheit (°F) to Celsius (°C). Enter a Fahrenheit reading and the calculator returns the Celsius value used by most of the world for weather, cooking, and medicine.
How It Works
This conversion reverses the two adjustments that separate the scales. You first subtract 32 to remove the offset, because the Fahrenheit scale puts the freezing point of water at 32 rather than 0. You then multiply by 5/9 to rescale the degree size, since a Celsius degree is larger — there are only 100 of them between freezing and boiling versus 180 Fahrenheit degrees. Because temperature is not a simple proportional quantity, the order matters: subtract before you multiply.
Worked Examples
Example 1 — body temperature. 98.6°F: (98.6 − 32) × 5/9 = 66.6 × 5/9 = 37°C.
Example 2 — room temperature. 72°F: (72 − 32) × 5/9 = 40 × 5/9 ≈ 22.2°C.
When to Use This Calculator
This conversion is useful when you read a US Fahrenheit forecast and want the Celsius figure friends abroad would recognize, when you adapt an American recipe to a metric oven dial, or when a thermometer or appliance reports in Fahrenheit and you need Celsius for a medical or school form. It also helps interpret fever readings between the two systems.
| Fahrenheit | Celsius |
|---|---|
| -40 °F | -40 °C |
| 32 °F | 0 °C |
| 50 °F | 10 °C |
| 68 °F | 20 °C |
| 98.6 °F | 37 °C |
| 100 °F | 37.8 °C |
| 212 °F | 100 °C |
Frequently Asked Questions
At what temperature are Fahrenheit and Celsius equal?
The two scales meet at −40 degrees, so −40°F is exactly −40°C — the only point where the readings match.
What is a quick way to estimate Fahrenheit in Celsius?
Subtract 30 and then halve the result. For example, 70°F becomes 40, halved to about 20°C, near the exact 21.1°C.
Is a fever of 100°F high?
A reading of 100°F is about 37.8°C, slightly above the normal body temperature of 37°C, so it indicates a mild fever.