Fº & Cº

My electronic converting gadget broke and I can’t remember the formula for converting Farenheit to Celsius. Anybody?

(C x 9/5) + 32 = F
(F - 32) x 5/9 = C


You can also try this site for various conversions:



Thanks :slight_smile:

“I think it would be a great idea” Mohandas Ghandi’s answer when asked what he thought of Western civilization

Lucky, you can also download a free conversion tool here: www.joshmadison.com/software

Also check out the “Constants and equations page” at http://www.tcaep.co.uk/

I recently learned a new one that’s much simpler to remember:

To convert from F to C, take the temperature, add forty, multiply by 5/9, and subtract forty.

e.g., 32 F +40 = 72 x 5/9 = 40 - 40 = 0
75 F + 40 = 115 x 5/9 = 63.888 - 40 = 23.888

To convert the other way, add forty, multiply by 9/5 and subtract 40 again.

e.g. 45 C +40 = 85 x 9/5 = 153 -40 = 113

It works nicely and is easier to remember. Just remember Celsius degrees are larger than Fahrenheit.


I just had to say that this +40/-40 method is very clever! I’ll use that for now on. :slight_smile:

If you don’t need to be too precise and are dealing with “normal” temperatures, you can get by with a really quick cheat.

To convert C to F - Double and add 30
To convert F to C - Subtract 30 and half.

For example, if the temperature is 25C then the above gives 80F (actual is 77F)

If the temperature is 85F this gives 27.5C (actual is just over 29C)

“You can’t run away forever; but there’s nothing wrong with getting a good head start.” — Jim Steinman

Dennis Matheson — Dennis@mountaindiver.com
Hike, Dive, Ski, Climb — www.mountaindiver.com

Now, if someone could tell me why it should be easier to perform two additions/subtractions instead of one – just because the number ends in 0? And you still have to remember if you must add first and then subtract or vice versa, and whether to multiply by 5/9 or 9/5…

Personally, I think division by 9 is the hard part (relatively speaking), and there’s just no getting around that without loss of accuracy.

Stupid little “rules of thumb” that for some reason remain locked in your brain forever:

Starting from 04°C, and adding 12 each time, the temperature in °F is the number (in °C) reversed. Like this:

04°C = 40°F
16°C = 61°F
28°C = 82°F
40°C = 104°F (just add the “1” before te “0”)
52°C = 125°F, and so forth.

It’s pretty accurate, and if you memorise certain figures, and don’t need mathematical accuracy, all you have to do is add 2°F per °C.

Go figure.

Come on! All these people with gimmicks cluttering up their minds. If you use the straightforward formulae given above AND THINK WHAT YOU’RE DOING, there’s no problem. You have a ratio of 5 wrt 9. You have an offset of +32 F at freezing and C starts there with 0. You know C has bigger degrees than F, because its range of numbers is smaller than those of the corresponding F degrees. Ever since (and, yeah, plenty of people before) calculators, people has chosen not to think what they’re doing.

Ray (Now, what was I doing?)

Actually converting the scales is no mystery to me. What is a mystery is, How do you make those cool little degree zeros you used in the topic of this post? Skeptic used them in his post as well. Lets have the dope on em.

ASCII ALT + codes. There were a couple of threads on them in the “Comments” Forum some time back, you might be able to find a list.

If you have Windows, run Explore for the file charmap.exe, then drag in onto your desktop as a shortcut. Each character is displayed on a grid. Select the appropriate font. Clicking on a character displays the ASCII ALT+ code on the lower right.

To get °, hold down the ALT key and type 0176 on the numeric pad. The rest work the same way. There are also some shortcuts that donot use 4 digits, but while I have a list of them, I have never seen them explained.

If you have a Mac, I can’t help.


alt 0176 ° yep that does it, Thanks TomnDeb.

He, he, he, he… my keyboard has it as default (spanish keyboard). All I have to do is strike “alt” plus the ° key! :slight_smile:

You could always use the HTML entity code “°” to make the °. That way, it’s cross-platform and standardized.

By the way, on a Mac, I think the degree is either Option-6 (like the ^) or Option-Shift-8 (like the *, and like the Option-8 bullet character).

Hey, aren’t you supposed to be at work?

RealityChuck wrote:

The reason this works is that -40° Fahrenheit is the same temperature as -40° Celsius.

Personally, I prefer to work in Kelvins.

Visit the Internet Stellar Database at www.stellar-database.com

You can also superscript a lower case ‘o’ with the (sup) (/sup) HTML codes (of course, substitute the parenthesis with angle brackets – also, subscript can be done with ‘sub’ in the code). So,

<BLOCKQUOTE><font size=“1” face=“Verdana, Arial”>code:</font><HR><pre>H[sub]2[/sub]O boils at 100[sup]o[/sup] C.

becomes **H[sub]2[/sub]O boils at 100[sup]o[/sup] C.**


Darn it!  I thought the **<tt>code </tt>**code was supposed to preserve formatting codes.  <sigh>
I guess I’ll force the issue with <font color="#009900">Netscape Composer</font>.  The code looks like this:

<td><tt><font size=+1>H<sub>2</sub>O boils at 100<sup>o</sup>

There, that’ll show <font face=""><font size=-1>UBB</font></font>
who’s boss!

<font color="#FF0000">P</font><font color="#FF0700">e</font><font color="#FF0F00">a</font><font color="#FF1600">c</font><font color="#FF1E00">e</font>