How this temperature converter works
Temperature can be measured on several scales. Celsius (°C) sets 0 at the freezing point of water and 100 at its boiling point. Fahrenheit (°F), common in the United States, puts freezing at 32 and boiling at 212. Kelvin (K) is the scientific scale that begins at absolute zero, and Rankine (°R) is the Fahrenheit-sized equivalent that also begins at absolute zero.
The converter applies the standard formulas. From Celsius: F = C × 9/5 + 32, K = C + 273.15, and °R = (C + 273.15) × 9/5. Going the other way, C = (F − 32) × 5/9. Whichever field you type into, the value is converted to Celsius internally and then out to every other scale, so all four stay in sync. Results are rounded to two decimals.
Quick conversion reference
| Celsius | Fahrenheit | Kelvin | Note |
|---|---|---|---|
| −40°C | −40°F | 233.15 K | Scales meet |
| 0°C | 32°F | 273.15 K | Water freezes |
| 37°C | 98.6°F | 310.15 K | Body temperature |
| 100°C | 212°F | 373.15 K | Water boils |
Reference note: 0 K is absolute zero (−273.15°C / −459.67°F). The Kelvin and Rankine scales have no negative values.
Frequently asked questions
- How do I convert Celsius to Fahrenheit?
- Multiply the Celsius value by 9/5 (1.8) and add 32: F = C × 9/5 + 32. For example, 25°C × 1.8 = 45, and 45 + 32 = 77°F.
- How do I convert Fahrenheit to Celsius?
- Subtract 32 from the Fahrenheit value, then multiply by 5/9: C = (F − 32) × 5/9. For example, (98.6 − 32) × 5/9 = 37°C.
- What is Kelvin?
- Kelvin is the SI base unit of temperature. It uses the same degree size as Celsius but starts at absolute zero, so K = C + 273.15.
- At what temperature are Celsius and Fahrenheit equal?
- They read the same value at −40 degrees: −40°C equals −40°F. It is the single point where the two scales cross.
- What is normal body temperature in Fahrenheit?
- About 37°C, which converts to 98.6°F using F = C × 9/5 + 32. It varies by roughly a degree through the day and between people.
- Is 0 K absolute zero?
- Yes. 0 kelvin is absolute zero — the lowest possible temperature — equal to −273.15°C or −459.67°F.