Its just basic math really.
How is your HCG mixed? How much HCG is in the bottle and how much BAW did ya add?
if you have a 10,000 IU bottle of HCG and you add 10ML water then you have 1000IU per ML correct?
Then if you have a 1ml syringe how many IU will you have if you fill it full? 1000IU
so if you want 250IU only and 1ml is 1000IU then logic would indicate you want 1/4 of a 1ml syring. Look at the marks on the side divide by 4 and fill it to that level.