Temperature Converter
Key Temperatures
Related Converters
Understanding Temperature Scales
The Three Main Scales
Celsius (°C)
Used by most of the world. Water freezes at 0° and boils at 100° (at sea level). Also called Centigrade.
Fahrenheit (°F)
Used in the United States. Water freezes at 32° and boils at 212°. Based on a brine solution's freezing point.
Kelvin (K)
Scientific scale. Starts at absolute zero (-273.15°C). No degree symbol used. Each Kelvin = 1°C.
Conversion Formulas
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
Quick Mental Conversions
Approximate Methods
- • C to F (rough): Double it and add 30
- • F to C (rough): Subtract 30 and halve it
- • -40 is the same: -40°C = -40°F (the only point they're equal)
Temperature Reference Points
| Description | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20-22 | 68-72 | 293-295 |
| Human body | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
| Oven (baking) | 180 | 356 | 453.15 |
About Absolute Zero
Absolute zero (0 Kelvin, -273.15°C, -459.67°F) is the lowest possible temperature. At this point, atoms have minimum energy and virtually stop moving. It's a theoretical limit that can be approached but never quite reached.
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply Celsius by 9/5 (or 1.8), then add 32. Formula: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 1.8) + 32 = 77°F. For a quick mental estimate: double the Celsius and add 30.
How do I convert Fahrenheit to Celsius?
Subtract 32 from Fahrenheit, then multiply by 5/9. Formula: °C = (°F - 32) × 5/9. For example, 98.6°F = (98.6 - 32) × 5/9 = 37°C. For a quick estimate: subtract 30 and divide by 2.
What is the difference between Celsius and Kelvin?
Kelvin and Celsius have the same scale size—a change of 1K equals a change of 1°C. The difference is the starting point: 0K (absolute zero) equals -273.15°C. To convert: K = °C + 273.15. Kelvin is used in science because it starts at absolute zero with no negative values.
At what temperature are Celsius and Fahrenheit equal?
-40 degrees is the only temperature where Celsius and Fahrenheit are the same. At -40°C = -40°F. This is because the two scales intersect at this point due to their different zero points and scale ratios.