I used the SRAM online calculator as a starting point and am currently running 33psi in the back and 31psi in the front. I only recently started to play with tire pressure, so I have a lot more experimenting to do.
I would recommend experimenting with lower pressures. I run 22-25psi on both my bikes. Which is still relatively high, but I'm running tubes (vs tubeless). Below 18-20psi the risk of pinch flats goes up with tubes.
I found, especially with my kid's bike when I ran too high, it rode really rough on peddlers. I run her around 15psi but she weighs 50lbs...
@AustinBike, what PSI were you running on your ridged on descents?