Temperature Converter
Celsius, Fahrenheit and kelvin — the two formulas and every reference point that matters.
Temperature Converter
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Units in this category
| Unit | Symbol | Exactly |
|---|---|---|
| Celsius (°C) | °C | reference unit for this category |
| Fahrenheit (°F) | °F | 0.55555556 °C with a -17.777778 offset |
| kelvin (K) | K | 1 °C with a -273.15 offset |
Where these factors come from
Temperature is affine, not proportional: °F = °C × 9/5 + 32 and K = °C + 273.15. Both relations are exact by definition, so no rounding is involved in any conversion on this site.
All 6 temperature pairs
Conversions by starting unit
Celsius (°C)
Fahrenheit (°F)
kelvin (K)
Common questions
Why does Fahrenheit use such odd numbers?
Daniel Fahrenheit anchored his scale to three reproducible points of his era — a brine mixture, melting ice and body temperature — which land at 0, 32 and roughly 96 on his scale. The freezing and boiling points of water then fall at 32 and 212.
Is −40 °C really equal to −40 °F?
Yes — it is the one temperature where both scales cross. Check it: −40 × 9/5 + 32 = −72 + 32 = −40.
What is absolute zero in each scale?
0 K, which is −273.15 °C and −459.67 °F. Nothing can be colder; the kelvin scale starts there by definition.