Mix Slider

Let's say you want a mixture to come out a certain way ...

Mix a 10% solution and a 30% solution to get a 15% solution
Mix hot water at 80°C and cold water at 20°C to get warm water at 35°C

And you want to know how much of each you need? This will help!

Example: Mix a 10% and 30% solution to get a 15% solution

Type 10 for the left hand side, 30 for the right hand side, adjust the slider until you get 15, and then put a Quantity of 100 (if you want 100 mL):

75 mL of 10% solution
25 mL of 30% solution

Will get you 100 mL of 15% solution

How the Math Works

The secret is finding the ratio of the two parts. Because a target closer left requires more of the Left solution, the formula needs to be this way:

Ratio of Left to Right = (Right − Target) : (Target − Left)

Using our example of the 10% and 30% solutions to get a 15% solution:

Left = 10
Right = 30
Target = 15

Let's plug them in:

Ratio of Left to Right:

(30 − 15) : (15 − 10)

Becomes:

15 : 5

Simplifies to:

3 : 1

This means we need 3 parts of the Left solution for every 1 part of the Right solution (making 4 parts in total).

If we want a total quantity of 100 mL:

Left: 34 of 100 mL = 75 mL
Right: 14 of 100 mL = 25 mL