How do you use this tool?
- Type a temperature value in the Celsius field to convert to Fahrenheit.
- Or type a Fahrenheit value to convert back to Celsius.
- Both fields update simultaneously, no submit button needed.
- Scroll down for a quick-reference conversion table covering common temperatures.
What This Tool Does
This converter instantly converts between Celsius (°C) and Fahrenheit (°F) in both directions. Celsius is the standard temperature scale in most of the world and in all scientific contexts. Fahrenheit is the daily-use scale in the United States, used for weather forecasts, cooking recipes, oven settings, thermostats, and medical temperature readings.
Understanding both scales is essential for Americans following metric recipes, travelers interpreting international weather forecasts, or anyone working with international temperature data.
How Does It Work?
Celsius to Fahrenheit:
°F = (°C × 9/5) + 32
°F = (°C × 1.8) + 32
Fahrenheit to Celsius:
°C = (°F − 32) × 5/9
°C = (°F − 32) ÷ 1.8
Quick mental math shortcut (±2° accuracy):
°F ≈ (°C × 2) + 30
°C ≈ (°F − 30) ÷ 2The exact formulas trace to the fixed points of each scale. Water freezes at 0°C / 32°F and boils at 100°C / 212°F at standard atmospheric pressure (1 atm / 101.325 kPa).
What Are the Conversion Reference Values?
| Celsius (°C) | Fahrenheit (°F) | Reference Point |
|---|---|---|
| −40 | −40 | Scales are equal |
| −18 | 0 | Freezer temperature |
| 0 | 32 | Water freezes / ice melts |
| 4 | 39 | Refrigerator ideal temp |
| 16 | 61 | Cool spring day |
| 20 | 68 | Comfortable room temp (cool) |
| 22 | 72 | Comfortable room temp (warm) |
| 37 | 98.6 | Normal human body temp |
| 38 | 100.4 | Fever threshold |
| 40 | 104 | High fever |
| 100 | 212 | Water boils (sea level) |
| 121 | 250 | Pressure cooker sterilization |
| 163 | 325 | Oven: low bake |
| 177 | 350 | Oven: standard bake |
| 204 | 400 | Oven: hot bake |
| 232 | 450 | Oven: high heat / pizza |
What Are US Cooking Temperature Values?
| Meat Doneness | Internal Temp (°F) | Internal Temp (°C) |
|---|---|---|
| Poultry (safe) | 165°F | 74°C |
| Ground beef (safe) | 160°F | 71°C |
| Beef, medium-rare | 135°F | 57°C |
| Beef, medium | 145°F | 63°C |
| Beef, well done | 160°F | 71°C |
| Pork (safe) | 145°F | 63°C |
| Fish (safe) | 145°F | 63°C |
USDA minimum safe temperatures apply. Always use a calibrated food thermometer.
What Are Common Use Cases?
Following an international recipe. A British recipe calls for baking at 180°C. Convert to 356°F, round to 350°F on your oven dial.
Interpreting a weather forecast abroad. A Paris weather app shows 28°C. That’s 82.4°F, a warm summer day, shorts weather.
Checking a fever. A digital thermometer reads 38.3°C. That’s 100.9°F, a mild fever, above the 100.4°F clinical threshold.
Setting a thermostat after international travel. You’re used to setting the thermostat at 22°C. In a US hotel that uses Fahrenheit, set it to 72°F.
Science class homework. Lab results in Celsius need to be reported in Fahrenheit for a comparison with US industrial standards.
Frequently Asked Questions
What is the formula to convert Celsius to Fahrenheit? Multiply by 9/5 and add 32: °F = (°C × 1.8) + 32. For quick mental math, the approximation °F ≈ (°C × 2) + 30 gives you a number within 2-3 degrees, good enough for judging weather.
What is the formula to convert Fahrenheit to Celsius? Subtract 32, then multiply by 5/9: °C = (°F − 32) × 5/9. Or divide by 1.8 after subtracting 32, which gives the same result.
At what temperature are Celsius and Fahrenheit equal? At exactly −40°. This is one of the few useful anchor points for understanding the relationship between the two scales. Below −40°, Celsius values are numerically larger (less negative) than Fahrenheit; above −40°, Fahrenheit values are larger.
What is normal body temperature in Fahrenheit? The standard reference is 98.6°F (37°C), established by German physician Carl Wunderlich in the 1850s. Modern studies show the average adult body temperature ranges from 97°F to 99°F (36.1°C to 37.2°C) and declines slightly with age. The clinical fever threshold in the US is 100.4°F (38°C).
What is a comfortable room temperature in Fahrenheit? Typical US thermostat settings range from 68°F to 72°F (20°C to 22°C) in winter and 74°F to 78°F (23°C to 26°C) in summer when cooling. The EPA and Department of Energy recommend 68°F for heating and 78°F for cooling to balance comfort with energy use.
Why does the US use Fahrenheit instead of Celsius? Historical momentum. Fahrenheit was the dominant scale in the English-speaking world when the US became independent. Most countries transitioned to the metric system (which includes Celsius) during the 20th century, but the US never mandated the switch for everyday consumer use. The scientific and medical communities in the US use Celsius, as does the military, but weather, cooking, and household temperature remain Fahrenheit in everyday American life.