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Conversion Formula for C to F

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Posted by: tivoman

Any body remember the conversion formula for converting celsius to fahrenheit and/or fahrenheit to celsius?

Thanks



Posted by: bdub

F = ((9 * C) / 5) + 32



Posted by: GoodSpike

This is easy to figure out in your head. The difference between boiling and freezing in each scale is 100 and 180. 100/180= 5/9 Then there's the absolute difference between the scales of 32 which you need to account for.

C to F is (C X 9/5) + 32
F to C is (F - 32) x 5/9



Posted by: tivoman

Thanks



Posted by: justapixel

Easy to figure out in your head?!?!

Speak for yourself!



Posted by: Graymalkin

To convert celsius to fahrenheit, I always did the following:

Take the celsius number (say, 20)
Double it (40)
Subtract 10% (40-4=36)
Add 32 (36+32=78)

Ergo, 20 degrees Celsius = 78 degrees fahrenheit



Posted by: GoodSpike

quote:
Originally posted by justapixel
Easy to figure out in your head?!?!

Speak for yourself!



I meant figuring out the formula, not doing the calculations. Once you figure out that a C degree is 5/8ths of a F degree, the rest is easy.



Posted by: GoodSpike

quote:
Originally posted by Graymalkin
To convert celsius to fahrenheit, I always did the following:

Take the celsius number (say, 20)
Double it (40)
Subtract 10% (40-4=36)
Add 32 (36+32=78)

Ergo, 20 degrees Celsius = 78 degrees fahrenheit



That is a method you can do in your head, assuming you can add 36 and 32 right! ;-)


36 + 32 is 68



Posted by: nextguard2

that formula means -40 degrees F = -40 degrees C



Posted by: bdub

For an approximate, head-capable, quick-and-dirty method, just multiply by two and add thirty to convert from C to F. It's accurate enough so that when you hear a weather report in your hotel room in Germany, you'll know immediately whether you'll need a coat, sweater, or short sleeves when you go out for the day.

"Today will be partly sunny with a high of 17 degrees..."

17*2=34
34+30=64

Better take a sweater.

(Of course, that's assuming you understand the German weather forecaster. ;))



Posted by: bdub

quote:
that formula means -40 degrees F = -40 degrees C
Yes, the two scales must cross somewhere. I used to convince classmates that the C to F conversion on their scientific calculators was broken by plugging in -40 and showing them that the number didn't change when they converted from one scale to the other.



Posted by: Charon2

Why stop there... A larger list...

Fahrenheit to Celsius: ((F-32)*5)/9=C
Fahrenheit to Kelvin: Fahrendeit to Celsius then C+273.15=K
Fahrenheit to Reaumur: ((F-32)*4)/9=Re
Fahrenheit to Rankine: F+459.67=Ra

Celsius to Fahrenheit: ((C*9)/5)+32)=F
Celsius to Kelvin: C+273.15=K
Celsius to Reaumur: (C*4)/5=Re
Celsius to Rankine: Celsius to Fahrenheit then F+459.67+ra

So, 72 F converts to:
22.2222222222222 Celsius
295.322222222222 Kelvin
531.67 Rankine
17.7777777777778 Reaumur



Posted by: Graymalkin

quote:
Originally posted by Karyk


That is a method you can do in your head, assuming you can add 36 and 32 right! ;-)


36 + 32 is 68



That explains why I got a calculator for my last birthday... :D



Posted by: jsmeeker

Why convert?? If the reason is to determine how warm.cold it will be outside when you go somewhere that reports temperature in celsius, just learn some temps.

0 is freezing. Its cold.
15 is moderate. Not cold. But not real warm.
35 is HOT!! Like Texas in the dead of summer.



Posted by: Steve Mehs

Or just get a $10 electronic pocket organizer that can convert any metric measurement into english or visa versa.



Posted by: ehopper

Simpler C to F:
C * 1.8 + 32 = F

F to C
F-32/1.8=C

I don't know why everyone is fooling around with this 9/5 stuff.



Posted by: ehopper

quote:
Originally posted by jsmeeker
Why convert?? If the reason is to determine how warm.cold it will be outside when you go somewhere that reports temperature in celsius, just learn some temps.

0 is freezing. Its cold.
15 is moderate. Not cold. But not real warm.
35 is HOT!! Like Texas in the dead of summer.



Speaking of which, it will 37 or 38 here tomorrow. It was 36 today, but I haven't heard for sure. It's 33 right now (8 PM)



Posted by: Spire

quote:
Originally posted by ehopper
I don't know why everyone is fooling around with this 9/5 stuff.
You're being facetious, right? Because 9/5 is equal to 1.8. Whenever I do the conversion, I just mentally multiply (or divide) by 1.8. Don't tell me some people actually multiply by nine then divide by five!



Posted by: RzE

It's easier to ballpark 35 * 9 oliver 5 than to do the same to 1.8.



Posted by: stormsweeper

quote:
Originally posted by ehopper

I don't know why everyone is fooling around with this 9/5 stuff.



Well, I usually find it faster to do quick stuff in my ead via fractions than decimals. But usually I ballpark these things using the *2 + 30 method.



Posted by: GoodSpike

quote:
Originally posted by ehopper
Simpler C to F:
C * 1.8 + 32 = F

F to C
F-32/1.8=C

I don't know why everyone is fooling around with this 9/5 stuff.



Wow! 1.8 equals doubling something and then taking 10% from the product? :-)

The 9/5ths & 5/9ths probably shows my age. Calculators either didn't exist when I learned the conversion, or they were $200 for a basic unit.

The double less 10% is probably the easiest to do in your head, but to figure it out if you don't remember the formula, you have to do the 100/180 thing, so you basically start in fractions.



Posted by: justapixel

So, since this entire conversation made absolutely no sense to me, (and I'm not kidding in the slightest) does that mean I'm going to fail my summer chemistry class? Should I give up the idea of being a nurse?

Would you want me to give you your meds?

2+2 = .......um...let me get the calculator out.....

I can't tell north from south or east from west either.

Now you know the worst about me.

Okay, I like cheesy lifetime movies too.



Posted by: mooseAndSquirrel

A few years back I worked in London. The stove in my apartment had a C scale. I had to use Excel every time I wanted to bake something!



Posted by: Graymalkin

I want my meds only from nurses who look like Moira Kelly or Julianna Margulies. And a nice sponge bath, too. :D

But seriously, Ann, don't worry -- you'll make a fine nurse. Just stick with it.



Posted by: GoodSpike

quote:
Originally posted by justapixel
So, since this entire conversation made absolutely no sense to me, (and I'm not kidding in the slightest) does that mean I'm going to fail my summer chemistry class? Should I give up the idea of being a nurse?

Would you want me to give you your meds?

2+2 = .......um...let me get the calculator out.....



I have a very good vet, and had a cat with a kidney condition for many years. She had similar problems with math and fractions. She prescribed 1/4 of a 2.5 mg Norvasc per day. I discovered that the 5 mg pills cost the same amount per pill and asked for a precription for that size since I could save 50%. It was hard for her to confirm my calculation that Spike would need 1/8th of a 5mg pill per day. But that didn't mean that as a vet she was far above average.

But why doesn't it make since. C freezing to boiling is 100 degrees (0 to 100). F freezing to boilding is 180 degrees (32 to 212). Thus a 100 C degree change equals a 180 F degree change. 100/180 reduces to 5/9. Thus each C degree is 9/5ths of an F degree, and each F degree is 5/9ths of a C degree. Thus, you merely need to convert on that basis, also taking into account the fact that freezing in F occurs at 32 degrees.

The two short cuts are simple. One doubles the amount and then reduces it by 10%. If you double 1 and take off 10% (.2) you end up with 1.8 which happens to equal 9/5. The other shortcut is merely a rough estimate. It doubles the C temp and then only subtracts 30 rather than 32. So it gives up the 10% adjustment but only takes 30 off instead of 32 to compensate. Simple, right?



Posted by: Charon2

Why do we even use those scales and not Kalven? If Kalven is an absolute scale...
So your local weather man could say "It will be a pleasant 295K today with a very slight breeze coming from the south."



Posted by: randyf

Damn you guys live in the stone age...

to convert from Celsius to Farenheit I flip the switch on my thermometer from "c" to "F"

to go back its the opposite...

sheesh...



Posted by: randyf

quote:
Originally posted by Karyk



But why doesn't it make since. <snip> Simple, right?



I guess.. didn't make SINCE to me :D



Posted by: Dale Sorel

quote:
Originally posted by Charon2
Why do we even use those scales and not Kalven? If Kalven is an absolute scale...
So your local weather man could say "It will be a pleasant 295K today with a very slight breeze coming from the south."



Sounds like a perfect day to wear my Kelvin-Kline jeans ;)



Posted by: randyf

quote:
Originally posted by Dale Sorel


Sounds like a perfect day to wear my Kelvin-Kline jeans ;)



While reading the Sunday Funnies -

Don'cha just LOVE Kelvin and Hobbes ? :p



Posted by: loubob57

I always remember that 20C is on the cool side of room temp, 10C is 50F, and 0C is cold (32F). I can kind of rationalize others from that



Posted by: scooterboy

I just can't believe that a simple formula question spawned 30 replies!

Oops, I guess mine makes 31...



Posted by: GoodSpike

quote:
Originally posted by randyf


I guess.. didn't make SINCE to me :D



Obviously I'm better at math than spelling.



Posted by: Darin

I usually just type "convert fahrenheit celcius" in the address bar of my browser, and a ton of conversion sites just pop up.

:D



Posted by: DJRobX

quote:
I usually just type "convert fahrenheit celcius" in the address bar of my browser, and a ton of conversion sites just pop up.
Yeah! I don't know why everyone is fooling around with this math stuff! ;)




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