Calculators & everyday math
Fahrenheit vs. Celsius: Reading Both Scales
Fahrenheit and Celsius measure the same thing on differently shaped rulers: they start from different zero points and use different step sizes. Knowing a few landmark temperatures on both scales makes either one easy to read.
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Landmark temperatures
| What | Celsius | Fahrenheit |
|---|---|---|
| Same on both scales | −40 | −40 |
| Water freezes | 0 | 32 |
| Cool room | 15 | 59 |
| Room temperature | 20 | 68 |
| Hot day | 35 | 95 |
| Typical body temperature | 37 | 98.6 |
| Water boils at sea level | 100 | 212 |
The size of a degree
Between freezing and boiling water there are 100 Celsius degrees but 180 Fahrenheit degrees, so one Celsius degree is 1.8 Fahrenheit degrees. A temperature rise of 5 °C is a rise of 9 °F.
Quick estimates
- Celsius to Fahrenheit: double it and add 30. 20 °C gives about 70 °F (exactly 68).
- Fahrenheit to Celsius: subtract 30 and halve it. 80 °F gives about 25 °C (exactly 26.6666667).
- The shortcuts are closest near everyday temperatures and drift further out.
Where each scale is used
The United States uses Fahrenheit for weather, cooking, and body temperature. Most of the world uses Celsius, and science uses Celsius and kelvin.
Fahrenheit vs. Celsius FAQ
- Is 0 °F freezing?
- It is well below freezing: 0 °F is about −17.8 °C. Water freezes at 32 °F.
- What is 30 °C in Fahrenheit?
- 86 °F.
- What is 100 °F in Celsius?
- About 37.8 °C (37.7777778).
- At what temperature are Celsius and Fahrenheit equal?
- −40 degrees.
- How much warmer is 1 °C than 1 °F?
- That compares a reading with a reading: 1 °C is 33.8 °F. As a step size, one Celsius degree equals 1.8 Fahrenheit degrees.
Related guides
- Temperature FormulasWhere the 32 and the 5/9 in the Fahrenheit–Celsius formulas come from, how to reverse them, and why temperature differences convert differently.
- Celsius, Fahrenheit, KelvinAbsolute zero, freezing, room temperature, and boiling on all three scales, why kelvin has no degree sign, and when scientists use each.
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