Fahrenheit to Celsius Converter
Convert Fahrenheit to Celsius and Kelvin instantly. Accurate temperature conversion calculator.
The Fahrenheit to Celsius Formula
Converting Fahrenheit to Celsius: °C = (°F − 32) × 5/9
Or equivalently: °C = (°F − 32) ÷ 1.8
Common conversions:
| Fahrenheit (°F) | Celsius (°C) | Context |
|---|---|---|
| −40 | −40 | Where scales meet |
| 0 | −17.8 | Very cold winter day |
| 32 | 0 | Water freezes |
| 50 | 10 | Cool spring day |
| 68 | 20 | Room temperature |
| 77 | 25 | Warm day |
| 86 | 30 | Hot summer day |
| 98.6 | 37 | Normal body temperature |
| 104 | 40 | Fever / extreme heat |
| 212 | 100 | Water boils at sea level |
| 350 | 177 | Moderate oven |
| 400 | 204 | Hot oven |
| 450 | 232 | Very hot oven |
Mental Math Shortcuts for F to C
For quick mental conversion from Fahrenheit to Celsius:
Approximate method: Subtract 30, then divide by 2. This gives results within 1-2°C in the common weather range.
Example: 80°F → (80 − 30) ÷ 2 = 25°C (actual: 26.7°C). Good enough for practical purposes.
Exact method: Subtract 32, then multiply by 5/9 (or divide by 1.8).
Example: 77°F → (77 − 32) × 5/9 = 45 × 5/9 = 25°C exactly.
Key reference temperatures to memorize: 32°F = 0°C (freezing) | 50°F = 10°C | 68°F = 20°C | 86°F = 30°C | 104°F = 40°C
The pattern: every 18°F increase = 10°C increase. So if you know 68°F = 20°C, then 86°F = 30°C, 104°F = 40°C, and working backward 50°F = 10°C, 32°F = 0°C.
Weather Temperature Guide for US Visitors Abroad
When visiting countries that use Celsius for weather forecasts, this guide helps:
| Forecast (°C) | In Fahrenheit | What to Wear |
|---|---|---|
| Under 0°C | Under 32°F | Heavy winter coat, layers, gloves |
| 0–5°C | 32–41°F | Winter coat essential |
| 5–10°C | 41–50°F | Heavy jacket, layers |
| 10–15°C | 50–59°F | Light to medium jacket |
| 15–20°C | 59–68°F | Sweater or light jacket |
| 20–25°C | 68–77°F | Light clothes, comfortable |
| 25–30°C | 77–86°F | Summer clothes |
| 30–35°C | 86–95°F | Hot, stay hydrated |
| 35+°C | 95+°F | Extreme heat, limit outdoor time |
Oven Temperatures: Fahrenheit to Celsius
American recipes use Fahrenheit; European and UK recipes use Celsius. Here's the complete conversion table for cooking:
| °F | °C | Gas Mark | Description |
|---|---|---|---|
| 250°F | 120°C | ½ | Very slow/low |
| 300°F | 150°C | 2 | Slow/low |
| 325°F | 165°C | 3 | Moderate low |
| 350°F | 177°C | 4 | Moderate |
| 375°F | 190°C | 5 | Moderate high |
| 400°F | 204°C | 6 | Hot |
| 425°F | 220°C | 7 | Hot |
| 450°F | 232°C | 8 | Very hot |
| 475°F | 245°C | 9 | Extremely hot |
Convection/fan ovens run about 25°F (15°C) hotter than conventional settings. If converting a fan oven recipe to a conventional oven, increase temperature by 15-25°C.
Body Temperature and Fever Chart
Body temperature converted between Fahrenheit and Celsius:
| °F | °C | Interpretation |
|---|---|---|
| Below 95°F | Below 35°C | Hypothermia — emergency |
| 97.0°F | 36.1°C | Low normal |
| 98.6°F | 37.0°C | Classic normal body temperature |
| 99.5°F | 37.5°C | Low-grade fever threshold |
| 100.4°F | 38.0°C | Clinically defined fever |
| 102.2°F | 39.0°C | Moderate fever |
| 104.0°F | 40.0°C | High fever — seek care |
| Over 104°F | Over 40°C | Hyperpyrexia — emergency |
The traditional 98.6°F (37°C) is an average. Research shows the modern average may be closer to 97.9°F (36.6°C). Oral readings are typically 0.5-1°F lower than rectal; armpit readings are typically 0.5-1°F lower than oral.
Scientific Temperature Scales
Beyond everyday use, scientists work with additional temperature scales:
Kelvin (K): The SI unit of temperature. Starts at absolute zero (−273.15°C / −459.67°F) — the theoretical minimum temperature. K = °C + 273.15. Used universally in physics, chemistry, and astronomy. Stars are described in Kelvin (the Sun's surface is ~5,778 K).
Rankine (°R): The Fahrenheit equivalent of Kelvin — starts at absolute zero using Fahrenheit increments. °R = °F + 459.67. Used in some US engineering applications (thermodynamics).
Temperature context: absolute zero (0 K / -273°C / -459°F) → liquid nitrogen boils (77 K / -196°C) → dry ice sublimates (195 K / -78°C) → water freezes (273 K / 0°C / 32°F) → room temperature (293 K / 20°C / 68°F) → water boils (373 K / 100°C / 212°F) → Sun surface (5,778 K).
Frequently Asked Questions
What is 72 degrees Fahrenheit in Celsius?
72°F = (72 − 32) × 5/9 = 40 × 5/9 = 22.2°C. This is a comfortable room temperature.
What is 100 Fahrenheit in Celsius?
100°F = (100 − 32) × 5/9 = 68 × 5/9 = 37.8°C. This is just above a clinical fever (which is defined as 38°C / 100.4°F).
How do I convert Fahrenheit to Celsius quickly in my head?
Subtract 30, then divide by 2 for a quick approximation. Example: 70°F → (70-30)/2 = 20°C (actual 21.1°C). For precise conversion: subtract 32, multiply by 5/9.
What temperature is cold in Celsius?
In weather terms: below 0°C (32°F) means freezing; 0-10°C (32-50°F) is cold; 10-15°C (50-59°F) is chilly; 15-20°C (59-68°F) is cool. What counts as 'cold' for people varies widely based on acclimatization — Canadians may find 10°C mild while Floridians bundle up.
Is 37 Celsius a fever?
No. 37°C (98.6°F) is the classic normal body temperature. A fever is clinically defined as a body temperature at or above 38°C (100.4°F). A low-grade fever is typically 37.5-38°C (99.5-100.4°F).
At what Fahrenheit temperature does it snow?
Snow forms when air temperature is 32°F (0°C) or below AND there is sufficient moisture in the air. Interestingly, some of the heaviest snows occur at temperatures of 28-32°F (-2 to 0°C) because cold air near freezing can hold more moisture than very cold dry air below 20°F (-7°C).
Why is 350°F the most common baking temperature?
350°F (177°C) is the 'sweet spot' for most baked goods — hot enough for efficient Maillard browning reactions (which create flavor and golden color) but not so hot that exteriors burn before interiors cook through. It's the default starting temperature in thousands of recipes.