# Scale conversion

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Can fractional scale be converted to a ratio, for example. . .

5/32" scale = 1:?

Mike

Edited by Stuntflyer
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In the most basic way of looking at it, 5/32" = 1 foot is the same as 5/32"=12".  Rearranging you get 5" = (12 x 32) or 5" = 384" which gives about 1"=76.8" (or 1:76.8).  What the 1:x gives is how many units (in this case inches) at full size are represented by 1 inch at scale size.  Also works for mm, cm, cubits etc.

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Wayne, thanks for the great explanation.

Mike

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I was taught to 'cross-multiply and then divide."  I can do that in my head to this day.

e.g.

3:32 = 5:X

3/32 = 5/X

32 times 5 = 160

160 divided by  3 = X = 53.3333

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Looks too complicated or this little black duck! I just use the Woodland Scenic Model Scaler AP. It is available on windows, iOS, Android and kindle for free!!!

http://woodlandscenics.woodlandscenics.com/show/page/modelscaler

Edited by hornet
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How would this work?

for 1/8" scale: 1/8"=.125, (12 ÷.125) = 1:96 scale

for 5/32" scale: 5/32"=.15625, (12÷.15625) = 1:76.8 scale

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Wouldn't have a clue - The AP has a custom scale option, feed in your numbers and see if it works. I have found the AP meets all my needs, so far in modelling. I thought it might be useful for others who may not have heard of it or used it. Seems to cover all the common scales. If it doesn't seem useful to you don't download it.

Edited by hornet
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Mike, have a look at this one - does exactly what you asked I think?

http://jbwid.com/scalcalc.htm

cheers

pat

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Pat, Looks like it scales up or down which is great, but not exactly what I was asking for. Still, this is a useful tool which I can use. Thanks!

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Mike did you see the bit at the bottom about entering fractions of an inch for conversion?  A bit clumsy but it seems to work?

cheers

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I did see that but again isn't that for scaling up or down as well? What I was trying to find out was how to convert for example, 1/4" scale to a ratio like 1:48. The formula is above in my 3rd post or you could use Wayne's method.

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dont understand this one but 1/4 = 1/25 so 5/32 = 1/64 so if you building a model thats 7/32 of the real thing then the scale would be 1/4571. you simply divide the second number by the first, but not quite sure if thats what your asking

Edited by williamDB
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William, I found the answer through Wayne's reply which I simplified my own crazy way. .example below

To find the scale ratio for 1/8" scale: 1/8"=.125, (12 ÷.125) = 1:96 scale

Edited by Stuntflyer
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i may be stupid but it doesn`t make any sense. for example ratio for 1/8 of an inch = 1/125 but the ratio of 1/8 of a foot is still 1/125

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William, I'm not saying that. I'm saying 1/8" = .125

1 foot = 12"

(12 ÷.125) = 1:96 scale

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i may be stupid but it doesn`t make any sense. for example ratio for 1/8 of an inch = 1/125 but the ratio of 1/8 of a foot is still 1/125

Since the scales for model building are given in a couple of ways (1/8" scale or 1:96 scale) it sometimes becomes necessary to find the ration (1:96) from a fractional inch (1/8").

The method Stuntflyer shows takes the fraction (1/8) does the division to get a decimal (0.125).  Since 0.125" = 1 foot at scale, and not sure why this works but it does, divide 12 inches per foot by the decimall (0.125) to get the ratio 1:96 (1 inch scale = 96 inches real).

Also works for other scales -

1/4"=1 foot becomes 12/0.25 = 1:48

3/32"=1foot becomes 12/0.9375 = 1:128

1/16" = 1 foot is 1:192

1/2" = 1 foot is 1:24 and so on.

This may not work as neatly when converting metric - haven't attempted that part yet!

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(Bob asks,  'What happens when the app machine breaks down?')

This is not rocket science, and it should be easy to do with a pencil and a piece of paper using multiplication and division as was learned in grade school.

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I works for any unit of measure because it is a ratio.  As long as you convert both sides of the equation to the same unit you can calculate it.  The method as Bob state above is to put the same unit of measure on both sides of the equation and cross multiply.  Wayne is doing the same thing, just doing part of it in his head and not realizing.

1/8" scale is the same as saying

1/8" = 1ft.      original ratio

=  1/8'= 12"/1    putting 1 foot into inches

cross multiply

1 x 1 = 1 and 8 x 12 = 96

= 1:96

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Since the scales for model building are given in a couple of ways (1/8" scale or 1:96 scale) it sometimes becomes necessary to find the ration (1:96) from a fractional inch (1/8").

The method Stuntflyer shows takes the fraction (1/8) does the division to get a decimal (0.125).  Since 0.125" = 1 foot at scale, and not sure why this works but it does, divide 12 inches per foot by the decimall (0.125) to get the ratio 1:96 (1 inch scale = 96 inches real).

Also works for other scales -

1/4"=1 foot becomes 12/0.25 = 1:48

3/32"=1foot becomes 12/0.9375 = 1:128

1/16" = 1 foot is 1:192

1/2" = 1 foot is 1:24 and so on.

This may not work as neatly when converting metric - haven't attempted that part yet!

understand now, sober today lol

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I apologize if I made anybody feel stupid.  For many years I was a research professor in a medical school, and occasionally I was recruited to teach either in a lecture hall and/or in the laboratory.  Those are two very different places and different crowds.

Well, I'll tell you, that when I was faced with 50--150 bright faces, then I learned that  'There are no stupid questions, but there are many stupid answers.'

It's a matter of understanding what a student is asking, what the student knows, and then explaining how a problem can be solved.  But it's more than that -- it's about teaching a student how to learn about how to solve a problem on their own, when nobody else is around to ask for help.

Edited by Bob Blarney

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