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calculator Celsius Fahrenheit

This is an easy way to calculate Fahrenheit into Celsius or reversely.

Lately on my US-trip

Just landed at JFK, played a little on the cell phone, to find some actual news. The first thing I noticed, there is more local then national news, and alot of advertising. Germany and Europe seems to be totally insignificant. But then the weather report: "We expect rain and fifty degrees." 50 Grad??? Oh yes, Fahrenheit, but how many degrees Celsius would that be?

Fahrenheit and Celsius

Both the temperature scales appeared seperately, the Fahrenheit is the older one. Fahrenheit is related to the same Romer-scale that inspired Celsius.

Simplified Fahrenheit matched a point for his scale, with the coldest temperature of a hard winter. Later scientific experiments with a freezing mixture with the melting-temperature, he estimated as 0°F, and the highest temperature, the body-temperature of a healthy person being 96 °F, not 100° Fahrenheit.

Celsius on the other hand took one of the most important elements being water for his scale. 0° Celsius is melting ice and 100° is steaming water.


Lets look to the fixed points of the Fahrenheit-scale:

cold winter:0 °Fperhaps -20 °C
body-temperature:rounded 100 °Frounded 40 °C

This shows two things. First, Fahrenheit needs app. 100 steps of degrees for app. 60 degrees Celsius. (exactly 90 for 50) and second, Fahrenheit's efforts to avoid negative temperatures were complete waste of time.

There is no exact calculation. For example 2 or 0,5 to use when your calculate from PS to KW. It doesn't work here. Because here it doesn't work to a perfect scale, and has no neutral starting position.

really obvious - We need mnemonics!


With a 100° you have got a fever. A Fahrenheit-temperature of 100 degrees is roughly 37,8 °Celsius. So by a child with such a temperature you would think of giving it medication.

61 is 16 Certain numbers are quite helpful, 61 °F is 16 °C, so the weather is where you will need a jumper.

82 is 28 Another helpful number: 82 °F is 28 °C, so swimming weather. And then in America with this temperature you would go to the beach. Going topless is definitely not allowed. Nudist colonies are few and far between.

minus 30 halves There are thirty halves in the card-game "thirty-one" (Big Tonka or Blitz). It moves from the Fahrenheit temperature of 30 degrees and half the result. Well, 60 °F are app. 15 °C [(60-30)/2].

This mnemonic gives 50 °F the exact result of 10 °C. For larger Fahrenheit temperatures, the values are slightly smaller.

exact calculation

°C = 5/9 * (°F - 32)

°F = 9/5 * °C + 32

Is there a temperature, where both numbers are the same?

Yes. -40 °F = -40 °C

More and physical correct information are on our sites about Celsius and Fahrenheit.