It's really impossible to measure your LSD dose. Sorry, but it's a fact. You can sometimes use others of the same batch as guideline, but even that is inexact.
LSD is such a potent chemical that you can get anywhere from 10ug to 500ug on a single 'tab' marketed for recreational use. Since the LSD is literally 'dropped' onto the blotter, it's possible that each one has a radically different quantity of LSD on it depending on the concentration of the liquid being dropped onto it. It's also possible that all of it gets absorbed into one quarter of it and cutting it results in a 2/3 chance of you getting none at all while the other person gets the full tab's worth.
So, my advice is to purchase 2 tabs and take 1 tab your first time. If you feel no different in 2 hours, take the second one. Otherwise, save it for a rainy day or take it later in your trip if you want to kick it up a notch. Don't take half of one unless you've already taken at least one, i.e. 1.5/2.5/3.5 tabs. That way if the half tab doesn't have much if any LSD on it, your whole trip isn't ruined.
