Convert Fahrenheit to Celsius
Convert Fahrenheit to Celsius with the classic (°F − 32) × 5/9 formula. Great for cooking, weather, HVAC, engineering, and academic work.
How to Convert Fahrenheit to Celsius
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value and multiply by 5/9.
Conversion Formula:
(value - 32) * 5/9Understanding the Conversion
Fahrenheit to Celsius conversions are essential when you encounter U.S.-based weather reports, cooking instructions, or HVAC settings but prefer metric units. The scales use different degree sizes and start points, so you must adjust both factors: subtract 32 to remove the Fahrenheit offset at water’s freezing point, then multiply by 5/9 to resize the degrees.
The exact formula is °C = (°F − 32) × 5/9. That means 32°F equals 0°C, 68°F equals 20°C, 98.6°F equals 37°C (body temperature), and 212°F equals 100°C (boiling point at sea level). Knowing a few anchors—like −40°F equals −40°C and typical room temperature 68–72°F equals 20–22°C—helps you sanity-check results.
Use this conversion when reading international forecasts, adjusting oven temperatures in imported recipes, configuring thermostat targets, interpreting medical thermometer readings, or aligning engineering specifications that mix Fahrenheit and Celsius. The converter keeps decimal accuracy so you can trust the result for sensitive tasks like fermentation, sous-vide cooking, lab experiments, or process controls.
For quick mental math, subtract 30 and halve the number for a close estimate. Example: 86°F → 86 − 30 = 56; half is 28°C (exact is 30°C). Use the calculator for final, precise numbers.
Conversion Examples
Example: Convert 68°F (room temperature) to Celsius
- Step 1: Subtract 32. 68 − 32 = 36.
- Step 2: Multiply by 5/9. 36 × 5/9 = 20.
- Step 3: Result is 20°C.
68°F = 20°C
20°C is a typical indoor comfort temperature in Celsius.
Example: Convert 451°F (oven temperature) to Celsius
- Step 1: 451 − 32 = 419.
- Step 2: 419 × 5/9 ≈ 232.8.
- Step 3: Result is about 233°C.
451°F ≈ 233°C
High-heat roasting often uses Fahrenheit; this shows the Celsius equivalent.
Example: Convert 98.6°F (body temperature) to Celsius
- Step 1: 98.6 − 32 = 66.6.
- Step 2: 66.6 × 5/9 = 37.
- Step 3: Result is 37°C.
98.6°F = 37°C
37°C is the standard reference for normal human body temperature.
Conversion Formula
Subtract 32 to remove the Fahrenheit offset set at water’s freezing point, then multiply by 5/9 to resize Fahrenheit degrees to the larger Celsius degree interval.
Conversion Chart
| Fahrenheit | Celsius |
|---|---|
| -40 | -40 |
| 0 | -17.78 |
| 32 | 0 |
| 50 | 10 |
| 68 | 20 |
| 77 | 25 |
| 86 | 30 |
| 98.6 | 37 |
| 122 | 50 |
| 212 | 100 |
Quick Conversion Tip
For a quick estimate, subtract 30 from °F and divide by 2. It is close for everyday temperatures; use (°F − 32) × 5/9 for exact results.
Unit Definitions
Fahrenheit (°F)
Fahrenheit defines water freezing at 32°F and boiling at 212°F under standard pressure, splitting the interval into 180 degrees.
Each Fahrenheit degree is 5/9 of a Celsius degree. Subtract 32 then multiply by 5/9 to convert to Celsius; add 459.67 to reach Rankine.
Celsius (°C)
Celsius sets 0° at water’s freezing point and 100° at boiling under standard pressure, creating a 100-degree interval.
Multiply Fahrenheit by 5/9 after subtracting 32 to reach Celsius. Add 273.15 to Celsius to reach Kelvin when absolute temperatures are needed.
Common Use Cases
- Travel: Read U.S. or Caribbean weather forecasts in Celsius.
- Cooking: Convert oven or smoker temps from Fahrenheit to Celsius.
- Healthcare: Translate thermometer readings for Celsius-based charts.
- HVAC: Align thermostat targets from Fahrenheit specs to Celsius set points.
- Science and labs: Bring Fahrenheit data into Celsius-based calculations.
- Education: Practice temperature formulas for exams and assignments.
Frequently Asked Questions
Why multiply by 5/9?
There are 180 Fahrenheit degrees between freezing and boiling versus 100 Celsius degrees, so each Fahrenheit degree is 5/9 of a Celsius degree.
Is -40°F the same as -40°C?
Yes. It is the intersection point of both scales and a good reference for extreme cold.
How do I convert small Fahrenheit decimals?
Use the exact formula. The calculator keeps precision, so values like 73.4°F convert cleanly to 23°C.
Does altitude change the conversion?
No. The conversion formula is fixed. Only boiling and freezing points shift slightly with pressure, not the relationship between scales.