First of all, CDS and CDH are not dosed in drops - drops vary too much and it is not worth taking drops of CDS as there is hardly any CLO2 in a few drops. Drops vary 50% up or down because of the viscosity of the solution, the diameter of the dropper opening, the angle you hold the dropper, the phase of the moon, etc.
I think you get the idea that I hate measuring solutions by "drops" because it is so inaccurate. MMS is dosed in drops if you make a single dose. Most people who still use MMS, make up a daily bottle and there you start with 1ml of MMS in a quart or liter of water.
The short answer to your question:
If i wanted to take the equivalent of 12-13 drops 0.5ml of CDS how may ml of CDH would i need to take.
is about 20% less CDH than CDS. If your dropper will dispense 24 drops equal to 1ml, then your "12-13 drops" of CDS would be 0.5ml. So, 20% less is 0.4ml of CDH. If you have a 1ml syringe, that is easy to measure. If you don't have a 1ml syringe, ask a pharmacist for one, without the needle, and they will probably give you one. At one time I asked a pharmacist and he gave it to me. They are used by diabetics so they are easy to find.
If you want to know how I arrived at 20% less CDH than CDS, ask and I will tell you.