Is there a way to tell what frequency I need a PWM to be?
No. You don't match rotations per second to PWM frequency. It needs to be much higher. You want it high enough so the motor runs smoothly (motor inertia smooths out motion and motor inductance helps smooth out current), but not so high the switching losses in your electronics is excessive. Often at least 8-10kHz, but you might want >20kHz if audible noise is an issue. You have quite a bit of leeway before it becomes outright "the wrong" frequency.