Apologies I read your post wrong, but similar rules apply.
You need to know the concentration of the liquid. There is no set conversion rule for converting units into mls/ cc. If something is 100 iu (u100) generally it's 1 unit is 0.1ml.
Also Finding a proper vein can be tricky it's not always the visual veins you see that are best. It can be really painful if you get it wrong, so please be careful x