You want to be somewhere between the recommended max inflation pressure and the lowest PSI that does not result in pinch flats for the hazards you might encounter during most of your riding on that bike.
I let my legs, my comfort and my data collected by my bike computer tell me what that pressure is. Online calculators might be right. But they haven't been right for me.
They for certain might be a good starting point. Then after keeping your tires at their recommended pressure for 6 -12 rides, change it up or down a few PSI and see what you think after 6 - 12 more rides. Judge by both by perceived effort and by how well your bike computer tells you you did on rides of the same routes.