Many of my students who come to live in the US have
difficulty learning the American way to measure temperature, the Fahrenheit (F)
scale. On the other hand, when Americans go abroad, it can be hard to
understand the Celsius scale (maybe one day the US will adopt this scale too,
but unfortunately, not anytime soon). While
electronic devices like phones and computers have made conversion between these
two scales less of a problem, it can still be useful to have a method to do it
quickly and easily without the aid of tech. I’ve developed such a method for
myself, which I’ve shared here in case others find it helpful.
Unfortunately, the mathematical conversion is not easy
unless you're really good at math, and even then, it takes some time. To do the
conversion you first add or subtract 32, and then multiply by 1.8 (0°C × 9/5 or
1.8 + 32 = 32°F). Another simple way is just to round up to 2.0, but this
doesn't give you as accurate a number and still takes longer.
In order to make this process easier, I use a simple trick
to do the conversion for the most common temperatures, from 0 C (32 F) to 40 C
(104 F). From 0 to about 20 C, every 5 degrees is about a 10 degree difference
in F. For example, 0 C is about 30 F (it’s
exactly 32 F), 5 is about 40 (41), and we can do this up to 20, which is 70 (68).
After 20 C, it’s no longer the same pattern. However, I memorize the final four
5 degree differences: 25 (77), 30 (85) 35 (95) and 40 (104), which isn’t that
difficult.
It's not a perfect system, but if you just take a little time to learn it, it can make the conversions much easier, and help you eventually learn them better.
Here is the simple conversion scale:
0 C: approximately 30 degrees F (exactly 32 degrees F)
5: 40 (41)
10: 50 (50)
15: 60 (59)
20: 70 (68)
25: 80 (77)
30: 85 (86)
35: 95 (95)
40: 105 (104)
