Math
Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin instantly. Enter a temperature in any unit and see all three conversions at once. Includes a body temperature guide, common reference temperatures, and the conversion formulas.
Temperature Conversion Formulas
°C → °F°F = (°C × 9/5) + 32
°F → °C°C = (°F − 32) × 5/9
°C → KK = °C + 273.15
K → °C°C = K − 273.15
°F → KK = (°F − 32) × 5/9 + 273.15
K → °F°F = (K − 273.15) × 9/5 + 32
Body Temperature Guide
Below 35°C / 95°FHypothermia
35–36.4°C / 95–97.5°FBelow normal
36.5–37.5°C / 97.7–99.5°FNormal
37.6–38°C / 99.6–100.4°FLow fever
38.1–39°C / 100.5–102.2°FModerate fever
Above 39.4°C / 103°FHigh fever
Common Temperature Reference Points
| Temperature | °C | °F | K | Note |
|---|---|---|---|---|
| Absolute zero | -273.15° | -459.67° | 0 | Coldest possible temperature |
| Dry ice (CO₂) | -78.5° | -109.3° | 194.65 | Sublimation point |
| Water freezing point | 0° | 32° | 273.15 | Ice melts at this point |
| Room temperature | 20° | 68° | 293.15 | Comfortable indoor temp |
| Normal body temperature | 37° | 98.6° | 310.15 | Healthy human range |
| Fever threshold | 38° | 100.4° | 311.15 | Medical fever definition |
| High fever | 39.4° | 103° | 312.55 | Seek medical attention |
| Water boiling point | 100° | 212° | 373.15 | At sea level, 1 atm |
| Oven (moderate) | 180° | 356° | 453.15 | Common baking temp |
| Sun surface | 5505° | 9941° | 5778 | Photosphere temperature |
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Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Formula: °F = (°C × 9/5) + 32. Examples: 0°C = 32°F (freezing), 20°C = 68°F (room temperature), 37°C = 98.6°F (body temperature), 100°C = 212°F (boiling). Quick mental estimate: double the Celsius, subtract 10%, and add 32. For example, 25°C → 25×2=50, 50−5=45, 45+32=77°F (actual answer: 77°F ✓).
How do I convert Fahrenheit to Celsius?
Formula: °C = (°F − 32) × 5/9. Examples: 32°F = 0°C, 68°F = 20°C, 98.6°F = 37°C, 212°F = 100°C. Quick mental estimate: subtract 32, then divide by 2 and add 10%. For example, 68°F → 68−32=36, 36÷2=18, 18+1.8=19.8°C (actual: 20°C, close enough for everyday use).
What is normal body temperature in Fahrenheit and Celsius?
Normal body temperature is 37°C (98.6°F), but the healthy range is broader: 36.5–37.5°C (97.7–99.5°F). Temperature varies throughout the day — typically lowest in early morning and highest in late afternoon. Fever is generally defined as above 38°C (100.4°F) by most medical standards. High fever is above 39.4°C (103°F).
What is the boiling point of water in Fahrenheit?
Water boils at 100°C (212°F) at sea level (standard atmospheric pressure of 1 atm). At higher altitudes, lower air pressure reduces the boiling point — at 5,000 ft (1,500m) altitude, water boils at about 95°C (203°F), which is why cooking instructions differ in the mountains.
What is Kelvin and when is it used?
Kelvin (K) is the SI base unit of temperature used in science and physics. Unlike Celsius and Fahrenheit, Kelvin starts at absolute zero (0 K = −273.15°C), the theoretical lowest possible temperature where all molecular motion stops. Kelvin has no negative values. It's used in thermodynamics, astrophysics, and chemistry. Note: Kelvin is written without a degree symbol — it's '300 K' not '300°K'.
What is the formula to convert Celsius to Kelvin?
K = °C + 273.15. It's the simplest of the three conversions — just add 273.15. Examples: 0°C = 273.15 K (water freezing), 100°C = 373.15 K (water boiling), −273.15°C = 0 K (absolute zero). To convert Kelvin back to Celsius: °C = K − 273.15.
At what temperature are Celsius and Fahrenheit the same?
Celsius and Fahrenheit are equal at −40°. That is, −40°C = −40°F. This is the only point where the two scales intersect. You can verify with the formula: °F = (°C × 9/5) + 32 → −40 = (−40 × 1.8) + 32 = −72 + 32 = −40 ✓