A “ratio” is simply a concentration relationship between the mass listed on a vial and the liquid volume added.
Formula
Concentration = vial amount in mg ÷ BAC water in mL.
Changing the water volume changes concentration and the corresponding liquid volume for an entered amount. It does not change the total mass in the vial.
Why calculators show options
Different BAC-water volumes can produce mathematically workable syringe marks. The highlighted “Easiest Mark to Read” option is only a scale-readability distinction; it is not a medical recommendation.
No universal ratio
The calculator cannot determine whether bacteriostatic water is compatible or which volume is appropriate. Follow the exact product instructions and qualified professional guidance.