°F = (°C × 9 ÷ 5) + 32
Temperature scales require both a scale and an offset.Conversion lab / temperature
Celsius to Fahrenheit Converter
Convert degrees Celsius to degrees Fahrenheit with the standard scale-and-offset formula.
Celsius to Fahrenheit Converter: Translate a Celsius thermometer reading into the Fahrenheit scale used on another forecast, thermostat or recipe. Enter the actual reading, including its minus sign for cold conditions. A temperature has a position on a scale: multiplying alone cannot account for the different zero points. Runs 100% locally in your browser with zero server file uploads.
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33.8
°Fdegrees Fahrenheit
-40 °C-40 °F
0 °C32 °F
20 °C68 °F
37 °C98.6 °F
100 °C212 °F
Degrees Celsius to degrees Fahrenheit conversion table
| degrees Celsius (°C) | degrees Fahrenheit (°F) |
|---|---|
| -40 °C | -40 °F |
| -30 °C | -22 °F |
| -20 °C | -4 °F |
| -10 °C | 14 °F |
| 0 °C | 32 °F |
| 10 °C | 50 °F |
| 20 °C | 68 °F |
| 30 °C | 86 °F |
| degrees Celsius (°C) | degrees Fahrenheit (°F) |
|---|---|
| 37 °C | 98.6 °F |
| 40 °C | 104 °F |
| 50 °C | 122 °F |
| 60 °C | 140 °F |
| 70 °C | 158 °F |
| 80 °C | 176 °F |
| 90 °C | 194 °F |
| 100 °C | 212 °F |
Rounded to seven significant digits; the converter above uses the full factor.
A forecast conversion, worked through
Let C be the Celsius reading and F the Fahrenheit reading. F = C × 9/5 + 32. For a forecast of 25 °C, calculate 25 × 9 = 225, divide by 5 to get 45, then add 32 to reach 77 °F. Keep the offset outside the multiplication; (25 + 32) × 9/5 would answer a different calculation.
The NIST temperature guide (https://www.nist.gov/pml/owm/si-units-temperature) gives the exact scale relationships. Converting a weather reading preserves its meaning; it does not calculate heat index, wind chill or a cooking time.
Reading units and sensible precision
Write °C and °F with their degree signs, but write kelvin as K, with no degree sign. A negative Celsius reading does not automatically imply a negative Fahrenheit value: −10 °C is 14 °F. The permitted lower boundary here is −273.15 °C, absolute zero. Extra decimal places describe the arithmetic, not extra accuracy in a household thermometer.
How to use it
- Enter the temperature in degrees Celsius.
- Read the converted degrees Fahrenheit value as it updates.
- Use the common values or open the reverse conversion to cross-check.
Privacy & limitations
Your value never leaves this browser. JavaScript floating-point arithmetic can round the last displayed digit; this general utility is not a substitute for calibrated or regulated measurement systems.
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Frequently asked questions
Why does doubling Celsius fail to give Fahrenheit?
Fahrenheit degrees are smaller and its zero is elsewhere. The exact multiplier is 9/5, followed by adding 32. Doubling and adding 30 is only a rough mental estimate; at 25 °C that shortcut gives 80 °F instead of 77 °F.
How can −40 °C also be −40 °F?
Set the two numerical readings equal: x = 9x/5 + 32. Subtract x to obtain 0 = 4x/5 + 32, so x = −40. The scales cross at one reading even though their graduations have different sizes.
Does a rise of 10 °C mean a rise of 50 °F?
A rise is a difference between readings, so the added 32 cancels. Multiply the change by 9/5: a 10 °C difference = 18 °F. By contrast, a thermometer reading of 10 °C converts to an actual temperature of 50 °F.
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