What does 1 in 5 dilution mean?

When you are doing dilutions the larger number is always the total final volume. The smaller number is the amount of the solute. The larger number minus the smaller number is the amount of the solvent. So a 1:5 or a 1 IN 5 dilution would be 1 part solute and 4 parts solvent to come to a total volume of 5.

When referencing ratiOS in mathematics 1:5 means 1 TO 5. The ratio is relative to the two items. For every 1 of the first you have 5 of the second.

It is critical if you are making dilutions to understand the difference as the two explanations are not interchangeable.