What si teh proper method for making dilutions?

Question

If a 1:1 dilution is an mix of equal parts, what is a 1:2 dilution? I always thought you subtracted the volume of the concentrated part from the final total volume. For instance, to make a 1:20 dilution, take one part of the concentrate and add 19 parts of the diluent so you'd have 1 part in a total volume of 20. Or do you add 1 part to 20 making the total volume 21?

Answer 1

Use the 1:1 dilution as a clue. In a 1:1 dilution, you would add 1L to 1L, resulting in 2L.

In a 1:2 dilution, you would add 1L to 2L, resulting in 3L.

In a 1:20 dilution, you would add 1L to 20L, resulting in 21L.