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Quickly Convert Between Celsius and Fahrenheit

This is how you effortlessly do it the old school way. America is still the only major country that uses Fahrenheit, so if you’re traveling to and from, you might want to know the differences.

I acknowledge technology is great. My phone converts between the two temperature scales seamlessly, and it’s not that hard to operate in Fahrenheit in a Celsius country or vice versa. But there comes a point in every nomad’s life when it’s about learning to flex that muscle, and to flex it well. There are two methods: the first one uses benchmarks to approximate, while the second one uses actual math. If you’re not great at math, never fear, because there’s also an easy shortcut, believe it or not.

The easiest way to learn the different scales is to remember benchmark equivalents of some of the conversions. Celsius is designed so that 0°C (32°F) represents the point at which water freezes and 100°C (212°F) represents the point at which water boils. A balmy 24°C (75°F) is equivalent to a stroll in Los Angeles; 15°C (59-60°F) is standard cool and foggy San Francisco weather.

Interestingly, the only point where both scales intersect is at -40, which is the point where I don’t even want to know what that feels like. Benchmarking is initially how I learned Celsius—which I know well—but the downside is that it doesn’t tell you how it interrelates with Fahrenheit.

There is, of course, a mathematical conversion for people interested in converting between the two scales. Each Celsius gradient (degree) is equal to 1.8 of a Fahrenheit degree, so you’ll be adding or subtracting in increments of 1.8 to correlate with the Celsius system. Though the official formulas for converting between the two systems include multiplying or dividing by 1.8 and also adding or subtracting by 32, this is rather convoluted just to figure out an approximate temperature.

The actual equations:

[pmath] Celsius = (Fahrenheit – 32)/1.8[/pmath]

[pmath] Fahrenheit = (Celsius*1.8) + 32[/pmath]

That, to me, is too complicated.

In fact, the easiest way is to round these factors to whole numbers. So, here, 1.8 rounds up to 2 while 32 rounds down to 30. By also rounding both up and down, it evens out the inaccuracies in the approximations to get closer to the actual value. The new method means multiplying or dividing by a factor of 2 instead and also adding or subtracting by 30.

Fahrenheit to Celsius

[pmath]Celsius = (F-30)/2 [/pmath]

To convert 70°F:


The result is ~20°C. The actual temperature is 21.1°C.

Celsius to Fahrenheit

[pmath]Fahrenheit = C*2 + 30 [/pmath]

To convert 15°C:

[pmath]=15*2 + 30 [/pmath]

The result is ~60°F. The actual temperature is 59°F.

That is the shortcut way for actually calculating between the two. Luckily, if you’re heading to the Caribbean, you may be in luck because the only other countries that use Fahrenheit are the Bahamas, Belize, the Cayman Islands, Palau and U.S. territories like Puerto Rico, Guam, and the U.S. Virgin Islands.

Everyone else uses Celsius.

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