Why had I not discovered this before?! I must have been living under a rock. Or just not spending as much time online and now am, thanks to lockdown.
I am contemplating two particular shelters (SMD Deschutes Vs. Zpacks Hexamid Pocket Tarp with Doors) and had been really spending load of time trying to work out how each would be given my height, how much space was offered etc etc and then stumbled across this site. Entered my height, the shelters I was interested in and BAM there were all the stats and a cool visual representation. Fun!
http://fitmytent.com/index.html