# Ratio help

• Mar 21st 2013, 03:59 AM
RhysJG
Ratio help
Hi all

Im currently doing some design work and need some help with ratio's

I have worked out that 1cm in my software equals 5.5cm in the real world.

I now need to add a border which I know is 3cm in the real world.

So 1cm = 5.5cm

What does 3cm equal?

I did 5.5/3 = 0.54
So 3 cm = 0.54 cm

Is that right??(Worried)
• Mar 21st 2013, 04:46 AM
HallsofIvy
Re: Ratio help
Quote:

Originally Posted by RhysJG
Hi all

Im currently doing some design work and need some help with ratio's

I have worked out that 1cm in my software equals 5.5cm in the real world.

I now need to add a border which I know is 3cm in the real world.

So 1cm = 5.5cm

What does 3cm equal?

I did 5.5/3 = 0.54
So 3 cm = 0.54 cm

Is that right??(Worried)

It's hard to believe you gave this any thought at all. 1 cm corresponds to 5.5 cm. Do you really think that a larger distance in the "real" world would correspond to a smaller distance in your model?

If the distance is three times as much in the real world, it should be three times as much in the model, not 1/3. Multiply by 3, do not divide by it.
• Mar 21st 2013, 05:34 AM
RhysJG
Re: Ratio help
Thanks Halls but I don't think I explained it properly.

I am using photoshop to design some window displays. I am using a photo of the front of the shop which has been set to a small size cm wise do it doesnt slow down the computer. Because of this I need to convert the size and find the ratio. So in photoshop it has a ruler and i am using that as my base.

I discovered that objects on the photo compared to the ruler in photoshop was 1cm in photoshop = 5.5cm in the real world (in the photo)

I had to add borders to some window frames, I know that in the real world these frames are 3 cm thick. So I need to make sure when I add them to photoshop it is to scale.

So if 1 cm in photoshop = 5.5 cm in the real world, what is 3cm real world to photoshop?
• Mar 21st 2013, 06:38 AM
ibdutt
Re: Ratio help
Always keep the quantity you are finding toward the right side
Now 5.5 cm in real world = 1 cm in software
Thus 1 cm in real world = 1/(5.5) cm in software
and 3 cm in real world = [1/(5.5) ] * 3 cm in software
that is 3 cm in real world will be 0.55 cm in the software
• Mar 21st 2013, 07:04 AM
RhysJG
Re: Ratio help
Thanks makes perfect sense