PCB - Altium designer resistor voltage divider calculation
The formula for a resistive voltage divider is Vout = (Vin * R2) / (R1 + R2). R2 is the "lower resistor" in the divider, and R1 is the "upper resistor". Vout is your desired output voltage and Vin is your supply voltage. You can pick either R1 or R2 and use basic algebra to solve for the other resistor. Do keep in mind that lower resistor values will draw excessive current in-circuit, so generally shoot for tens or hundreds of kilohms for your chosen resistor values.