Temperature Converter
Result
33.8 Fahrenheit
How these units are defined
The kelvin is the SI base unit, defined through the Boltzmann constant. A Celsius temperature is the kelvin temperature minus 273.15, and a Fahrenheit degree is 5/9 of a Celsius degree with water freezing at 32 °F. Rankine uses Fahrenheit-sized degrees from absolute zero.
| Unit | Equals |
|---|---|
| 1 Fahrenheit | see formula below |
| 1 Kelvin | see formula below |
| 1 Rankine | see formula below |
Worked examples
- -40 Celsius = -40 Fahrenheit
- 0 Celsius = 32 Fahrenheit
- 37 Celsius = 98.6 Fahrenheit
- 180 Celsius = 356 Fahrenheit
Common mistakes
- Temperature readings and temperature differences convert differently: a reading uses °F = °C × 9/5 + 32, but a change of 10 °C is a change of 18 °F (no +32).
- −40 is the same reading in °C and °F; the popular "double it and add 30" shortcut drifts several degrees away from about 10 °C.
- Kelvin is written without a degree sign (300 K) and cannot be negative.
Temperature conversions
Frequently asked questions
How do I convert Celsius to Fahrenheit?
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. Formula: °F = (°C × 9/5) + 32.
What is absolute zero in different temperature scales?
Absolute zero is 0 Kelvin, -273.15°C, or -459.67°F. It is the lowest possible temperature.
Why does the US use Fahrenheit?
The US adopted Fahrenheit before the metric system was developed. It remains in use due to historical inertia and cultural familiarity.
Sources for these factors
- The International System of Units (SI Brochure), 9th edition — BIPM
- Guide for the Use of the International System of Units (SP 811), Appendix B: conversion factors — NIST
- Handbook 44 (2024), Appendix C: General Tables of Units of Measurement — NIST
Last reviewed against these sources. An automated check recomputes every factor from its definition on each build. How we check accuracy