Tool for measuring pivot to spindle distance?

I have a very old original manufacture Dennesen Protractor. If I need to locate the pivot of a tonearm I want to mount, I take a piece of clean white paper and make two pen marks on it, at a distance from one to the other that is equal to the desired P2S distance. Then I set the spindle hole of the Dennesen centered on one of the two dots and line up the vertical steel pointer at the other end of the Dennesen with dot number 2. Then I lock in the Dennesen at this distance. I then place the Dennesen over the tt spindle, and the vertical steel pointer tells me where the tonearm pivot point needs to be. So, I recommend a Dennesen or Dennesen type protractor to kill 2 birds with one stone, as they say. (Because once you've mounted the tonearm, you can use the Dennesen again to set pivot to stylus distance.) Dertonearm offers an accessory attachment to his protractor, exclusively for setting P2S, but it costs several hundred dollars over and above the cost of the protractor.

Dear Oakris, You wrote, "I think I am confusing folks, or I am confused myself, lol, I know what the spindle to pivot distance is supposed to be, just looking for a tool that will give me a reasonably accurate measurement."

I realized that not everyone was responding to your actual question, and I understand the problem. Which is why I posted about how I use the Dennesen protractor to set P2S (that's the standard abbreviation in these parts for "pivot to spindle"). It works. What I then pointed out is that the Dennesen is really a protractor for aligning a cartridge. So after you've mounted your tonearm at the exact correct P2S distance, then you can use it again, as Mr Dennesen intended.

My last post was written before your last post got posted.
Scour the for sale sections of this and other audio websites and even eBay, and I think you should be able to find a Dennesen or a Dennesen copy for under $100, with some patience.

Truthfully, if we accept on faith that the P2S should be within +/-1mm of exactly correct (even better than that, according to some), I don't know how you will achieve the goal with calipers. If no Dennesen, you might consider taking a stiff sheet of paper or a very thin sheet of plastic. Then take a very accurate metric ruler and measure out the desired P2S. Then carefully punch a hole the size of your spindle, centered on one of the end marks. Then punch a much smaller hole centered on the other mark. You should do fine with that. No calipers needed, only a good metric ruler.