Percent of Occupants with access to the fixture.

100% for all. The calculator automatically adjusts for males using urinals.

Looking at the formulas in the calculator, the "percent of males expected to use restrooms with urinals" adjusts the number of daily uses from the standard (2WC/1urnial).  The "percent of occupants" cell adjusts the total baseline and design gallons (total daily uses times flush rate times percent of occupants). If you follow the instructions and you have male restrooms without urnials you will be changing both of these numbers to reflect less than 100%. How is that not double counting? Please help me out; my brain hurts.

I think the best way to think of it is that the % of males field and the % of occupants field are there to measure different things. And the % of occupants field pretty much only comes into play when you're putting different models of the same fixture type in the calculator.  

Let's say you have a project with two sets of identical male & female restrooms. All four have 1.28 gpf WCs, and both male restrooms have urinals. This is the default, so you don't change either the % of males or the % of occupants.

Now let's say you take the urinals out of one of the male restrooms. Only half the male occupants will use the restroom with urinals. You change the % of males field to 50%, which causes the form to correct the daily uses to reflect fewer male urinal uses and more male WC uses. You leave the % of occupants field at 100%, because 100% of males will use either the urinal or 1.28 gpf WC, and 100% of females will use the 1.28 gpf WC.

Next, say you keep those 1.28 gpf WCs in one set of restrooms, but the other has 1.6 gpf WCs. (Typically happens when some fixtures are existing, or will be fit out by unknown tenants.) Now half your WC-using occupants will use a WC with a different flush rate. You include both the 1.28 and the 1.6 fixture on separate lines in the table and make the % of occupants field 50% for each.

I hope that makes sense...at least as much sense as it can make to try describing a complicated spreadsheet in words :) 

That does make sense. An added instruction that for each fixture type the % of occupants must add up to 100. The other note about if installed in every restroom could also be more clear because if urinals are not installed in every restroom it would lead me to make % occupants for urinals less than 100%

The new v4 V04 calculator explains everything nicely