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 Soap Making Forum > how to calculate a ratio?
08-06-2017, 09:36 PM   #1
Spice
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how to calculate a ratio?

So I am bad at math....how does one figure a ratio??
Like 25% of water to oils or 38% lye concentration? Or any ratio

08-06-2017, 11:29 PM   #2
earlene
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Well, first, if you are using a lye calculator such as SoapCalc or Soapee, or any of the others I generally see online, the calculator does that for you. You only have to choose which you want in the appropriate box. If you don't make a selection in that box, the calculator chooses a default number.

If you are mixing something like a fragrance mixture to create your own fragrance, perhaps this will help understand Ratios:

1:3 = 1 part to 3 parts = a ratio of 1 to 3 (for a total of 4 parts)
So if you are mixing fragrances (Essential oils, for example) and you need a ratio of 1 part to 3 parts, what you end up with is 4 parts, where 1 part is the least amount of one EO and the other 3 parts are a different EO.

In terms of percentage the same 1:3 ratio becomes 25% of the first EO and 75% of the second EO = 100% of the total fragrance.

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08-07-2017, 02:18 PM   #3
jbrewton

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25% of Water to Oil. In this case if you have 100g of oil you would use 25g of water.

Here is how it works: Cross Multiplication

25%/100% = Xg/100g

No multiply 25x100 = 2500

Now multiple 100 times X = 100X

So 2500 = 100X

Divide both sides by 100 and you get 25 = X

Hope that helps.

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08-07-2017, 05:53 PM   #4
Spice
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Quote:
 Originally Posted by earlene Well, first, if you are using a lye calculator such as SoapCalc or Soapee, or any of the others I generally see online, the calculator does that for you. You only have to choose which you want in the appropriate box. If you don't make a selection in that box, the calculator chooses a default number. If you are mixing something like a fragrance mixture to create your own fragrance, perhaps this will help understand Ratios: 1:3 = 1 part to 3 parts = a ratio of 1 to 3 (for a total of 4 parts) So if you are mixing fragrances (Essential oils, for example) and you need a ratio of 1 part to 3 parts, what you end up with is 4 parts, where 1 part is the least amount of one EO and the other 3 parts are a different EO. In terms of percentage the same 1:3 ratio becomes 25% of the first EO and 75% of the second EO = 100% of the total fragrance.
interesting how i see that, so the one is a 25 of 100 ( like you said) and the other is three quarters=75.

This will help how I think when I am doing a blend.

Quote:
 Originally Posted by jbrewton 25% of Water to Oil. In this case if you have 100g of oil you would use 25g of water. Here is how it works: Cross Multiplication 25%/100% = Xg/100g No multiply 25x100 = 2500 Now multiple 100 times X = 100X So 2500 = 100X Divide both sides by 100 and you get 25 = X Hope that helps.
Like this too. I like to get different views, because I have a brain that see math as greek. Thanks

12-09-2017, 05:04 AM   #5
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Except that doesn't work at all, especially not for your dollar example at all -

1/4 is a quarter, the coin. Four of them in a dollar. The 4 of 1/4 means 4 parts, and the 1 means 1 of those 4 parts.

If you write that as 1:4, you now have 5 parts, not 4. You add the two parts together to get the whole. 1:1 means each side is 50%, not 100%, the whole is 2 and each side is 1.

So if 1/4 is a quarter and you write it as 1:4, there are now 5 quarter coins in total. Handy for getting some extra money, not so good for being useful maths.
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12-18-2017, 05:34 AM   #6
Spice
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Quote:
 Originally Posted by The Efficacious Gentleman Except that doesn't work at all, especially not for your dollar example at all - 1/4 is a quarter, the coin. Four of them in a dollar. The 4 of 1/4 means 4 parts, and the 1 means 1 of those 4 parts. If you write that as 1:4, you now have 5 parts, not 4. You add the two parts together to get the whole. 1:1 means each side is 50%, not 100%, the whole is 2 and each side is 1. So if 1/4 is a quarter and you write it as 1:4, there are now 5 quarter coins in total. Handy for getting some extra money, not so good for being useful maths.
Thanks for clearing that up, how can I figure a 1:4 math? I see a lot of "just do a 3:2". So how can I, in my stupid little head, figure that out.

12-18-2017, 06:00 AM   #7
The Efficacious Gentleman

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1:4 is a 5 part total, so think of it like 20 cents in the dollar.

Working with ratios depends on the direction in which you are working If you have your total amount and want to work out how that splits over the ratio:

Take your amount (let's say 175) and divide it by the sum of both sides of the ratio (1:4 becomes 1+4 =5). So one part of our ratio is 175/5=35. On one side we have 1 part and on the other 4, so we have to multiply that 35 by the numbers on both sides of the ratio. So 35*1 = 35. 35*4=140.

To check, add those two together and they make 175, which was our starting number.

When coming from the other direction, where you have a ratio and you know the amount for one side of it-

So I have a ratio of 1:4 and I know that the right side is 140. To work out the rest, I divide that 140 by 4 to get the base amount for each part of the ratio. 140/4 is 35. So we can now multiply that by the sum of the ratio parts (35*(1+4)) to find out the final amount, or multiply it by the left side of the ratio to find out how much that it.

I hope that didn't make it worse

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