Temperature conversion between Celsius, Fahrenheit, and Kelvin comes up constantly — checking weather in a different unit, following a recipe or scientific measurement from another country, or converting a thermostat setting. This page covers how to convert Celsius to Fahrenheit and Fahrenheit to Celsius using the exact formulas, a full conversion chart for commonly needed values, and how Kelvin fits into temperature conversion for scientific contexts. Dedicated one-way shortcuts live at Celsius to Fahrenheit and Fahrenheit to Celsius. Browse all converters if you need a different tool.
How to Convert Celsius to Fahrenheit
The C to F Formula
°F = (°C × 9/5) + 32
This is the exact formula behind every Celsius to Fahrenheit conversion. Multiplying by 9/5 (or 1.8) scales the Celsius degree size to match Fahrenheit's smaller degree increments, and adding 32 accounts for the different zero points of the two scales (0°C is 32°F, not 0°F).
How to Convert Fahrenheit to Celsius
The F to C Formula
°C = (°F − 32) × 5/9
This reverses the process — subtracting 32 first to align the zero points, then scaling by 5/9 to convert Fahrenheit's smaller degree increments back to Celsius's larger ones.
Celsius to Fahrenheit Conversion Chart
Common Celsius to Fahrenheit Conversions
A full reference table covering commonly searched Celsius to Fahrenheit conversions:
| Celsius | Fahrenheit |
|---|---|
| 17°C | 62.6°F |
| 18°C | 64.4°F |
| 19°C | 66.2°F |
| 20°C | 68°F |
| 22°C | 71.6°F |
| 23°C | 73.4°F |
| 28°C | 82.4°F |
| 30°C | 86°F |
| 32°C | 89.6°F |
| 40°C | 104°F |
| 170°C | 338°F |
| 180°C | 356°F |
| 190°C | 374°F |
| 200°C | 392°F |
Each value in this chart is calculated using the exact C to F formula above — for example, 40°C converts as (40 × 9/5) + 32 = 72 + 32 = 104°F, and 180°C (a common oven temperature) converts as (180 × 9/5) + 32 = 324 + 32 = 356°F.
Kelvin: The Third Temperature Scale
Converting to and From Kelvin
Kelvin is the standard scientific temperature scale, used throughout physics and chemistry because it starts at absolute zero (the theoretical lowest possible temperature) rather than an arbitrary reference point like Celsius or Fahrenheit. Converting to and from Kelvin uses these formulas:
K = °C + 273.15
°C = K − 273.15
This calculator supports Kelvin alongside Celsius and Fahrenheit, converting directly between any of the three scales.
Why This Converter Validates Against Absolute Zero
What Happens Below Absolute Zero
Absolute zero (0 K, equal to −273.15°C or −459.67°F) is the theoretical point at which molecular motion stops entirely — no temperature can physically go lower than this. This calculator validates any input against absolute zero, flagging an entry as invalid if it falls below this theoretical minimum in any of the three scales, rather than silently returning a physically impossible result.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5, then add 32. For example, 40 degrees Celsius converts to 104 degrees Fahrenheit.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value, then multiply by 5/9.
What is 180°C in Fahrenheit?
180 degrees Celsius equals 356 degrees Fahrenheit, a common oven-temperature conversion.
What is 200°C in Fahrenheit?
200 degrees Celsius equals 392 degrees Fahrenheit.
How do I convert Celsius or Fahrenheit to Kelvin?
Add 273.15 to a Celsius value to get Kelvin. For Fahrenheit, first convert to Celsius, then add 273.15.
What is absolute zero?
Absolute zero is 0 Kelvin, equal to -273.15 degrees Celsius or -459.67 degrees Fahrenheit, the theoretical lowest possible temperature.
Does this calculator check for impossible temperature values?
Yes. Any input below absolute zero in any scale is flagged as invalid, since it would represent a physically impossible temperature.
Is this temperature converter free to use?
Yes. It is free, requires no sign-up, and converts between Celsius, Fahrenheit, and Kelvin instantly.