To convert Celsius to Fahrenheit, multiply by 9/5 and add 32: °F = °C × 9/5 + 32, so 20 °C becomes 68 °F. This temperature converter handles all six directions between Celsius, Fahrenheit, and Kelvin, shows your temperature on all three scales at once, and displays the exact formula it used.
Celsius is the everyday scale in most of the world, Fahrenheit dominates in the United States, and Kelvin is the scientific standard that starts at absolute zero. Because the three scales have different zero points, converting requires a formula with an offset — not a simple multiplier — which is why this page spells the formulas out.
The Temperature Conversion Formulas
All six conversions come from two facts: water freezes at 0 °C = 32 °F, and a Celsius degree is 9/5 the size of a Fahrenheit degree. Kelvin uses Celsius-sized degrees starting from absolute zero.
- Celsius to Fahrenheit: °F = °C × 9/5 + 32
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9
- Celsius to Kelvin: K = °C + 273.15
- Kelvin to Celsius: °C = K − 273.15
- Fahrenheit to Kelvin: K = (°F − 32) × 5/9 + 273.15
A quick mental shortcut for C to F: double the Celsius value, subtract 10%, then add 32. For 20 °C: 40 − 4 + 32 = 68 °F exactly.
Common Reference Points
Memorizing a few anchor temperatures makes any conversion easier to sanity-check:
- Absolute zero: −273.15 °C = −459.67 °F = 0 K
- Water freezes: 0 °C = 32 °F = 273.15 K
- Cold winter day: −10 °C = 14 °F
- Room temperature: 20 °C = 68 °F
- Normal body temperature: 37 °C = 98.6 °F
- Hot summer day: 35 °C = 95 °F
- Water boils (at sea level): 100 °C = 212 °F = 373.15 K
- Moderate oven: 180 °C = 356 °F
- Hot oven: 200 °C = 392 °F (a very common recipe conversion)
- Pizza oven: 250 °C = 482 °F
The two scales cross at −40°, where −40 °C = −40 °F.
Worked Examples: 200 °C to °F and 98.6 °F to °C
Convert 200 °C to Fahrenheit — the classic oven-temperature lookup. Apply °F = °C × 9/5 + 32: 200 × 9/5 = 360, plus 32 gives 392 °F. Most US recipes round this to 400 °F, so a UK recipe’s “200 °C fan/gas mark 6” maps to roughly 390–400 °F.
Convert 98.6 °F to Celsius. Apply °C = (°F − 32) × 5/9: 98.6 − 32 = 66.6, and 66.6 × 5/9 = 37 °C — the textbook normal body temperature.
Convert 25 °C to Kelvin: 25 + 273.15 = 298.15 K, the standard “room temperature” used in chemistry.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (that is, 1.8) and add 32: °F = °C × 9/5 + 32. For example, 30 °C × 1.8 = 54, plus 32 = 86 °F. For a fast estimate, double the Celsius number and add 30 — accurate to within a few degrees for everyday weather temperatures.
What is 200 C in Fahrenheit?
200 °C equals 392 °F, using 200 × 9/5 + 32 = 392. In cooking, 200 °C corresponds to gas mark 6 and is usually rounded to 400 °F in American recipes — a moderately hot oven suited to roasting vegetables and baking pastry.
What is normal body temperature in Celsius and Fahrenheit?
Normal body temperature is about 37 °C, which equals 98.6 °F. In practice healthy readings range from roughly 36.1–37.2 °C (97–99 °F). A fever is commonly defined as 38 °C (100.4 °F) or higher measured orally.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit read the same at −40 degrees: −40 °C = −40 °F. You can verify with the formula: −40 × 9/5 + 32 = −72 + 32 = −40. It is the only temperature where the two scales intersect, because they have different zero points and degree sizes.
What is the Kelvin scale used for?
Kelvin is the SI base unit of temperature, used in science because it starts at absolute zero (0 K = −273.15 °C), the point where molecular motion is minimal. Kelvin degrees are the same size as Celsius degrees, so converting is simple addition: K = °C + 273.15. Kelvin values are written without a degree symbol.