°F US customary / imperial
Measures: Temperature — how hot or cold
Degree Fahrenheit
The US everyday temperature unit.
TemperatureHow it's defined
Defined today via the kelvin: T(K) = (T(°F) + 459.67) × 5/9, exactly. Water freezes at 32 °F and boils near 212 °F at sea level — 180 steps apart, which is why one °F step is 5/9 of a °C step.
°F = °C × 1.8 + 32 — exacta difference of 1 °F = a difference of 5/9 °C — exact (why Temperaturii converts anomalies by ×1.8 with no +32)
Convert — honestly
°F equals
255.927778 K
Kelvin · factor exact — the base unit itself
-17.2222222 °C
Degree Celsius · factor exact — exact by definition
Conversions run through the kelvin using the stated factors — no rounding beyond display precision, and every factor says whether it's exact or measured.
Where you meet it
- US weather, ovens, and thermostats
- Temperaturii's °F toggle uses its difference rule ↗ open temperaturii
Other ways to measure temperature
Source
This page is an authored summary of the authoritative definition — checkable one click away.
NIST Special Publication 811 — Guide for the Use of the SI