IU's are standardized units of measurement for various drugs, vitamins etc which can be based on weight or volume, but it depends on the individual substance. The amount of substance in an IU is not consistent between different substances. For example, 1000 IU of vitamin D are not the same weight or volume as 1000 IU of HCG.
On top of that it becomes even more confusing if you are using an insulin syringe marked in IU's. Syringe IU's do not directly correlate with IU standards for drugs except insulin. If there is an equal correlation with other substances, it is a pretty random match.
With HCG this is important. HCG can be mixed at different concentrations, therefore the number of IUs can vary per ml.
Pharmaceutical packaged HCG comes in different amounts and can come with different mixing volumes of fluid compared to compounded HCG. For example if you buy HCU from Empower pnarmacy (compunded HCG), it typically comes with instructions to mix 1 ml of diluent with 1000IU of HCG (or 5ml for 5000IU, or 10ml with 10,000IU). That results in concentration of 1000IU/ML. But if you want to inject half the amount of fluid for the same dose, you can mix only 0.5ml of fluid to 1000IU for a concentration of 2000IU/ml. This is exactly what some of us do with HCG ordered overseas because the vials are to small for 1000IU/ML. The result is our HCG solution has twice the IU's per ML.
Also, @Westin, syringes do not show MG marks. a MG is a weight. A ML is a volume. Syringes either show ML or IU marks. The IU scale on insulin syringes is specifically for insulin, but it is easy to translate for HCG dosing. 10 Insulin syringe units equals 0.1 ML, or 100 units equals 1ML. But these syringe units are not indicative of HCG units, The syringe units and the HCG IUs are entirely different things. You have to know the mixing ratio/concentration of the HCG solution and how to translate that into the volume for injection.
If you want to figure it out for sure, please LMK:
-What is the mixing ratio for your HCG in IU per ML?
-How many IUs do you want to inject?
-Are you using a syringe marked in ML or an insulin syringe marked in IU?