How it is calculated
If a load is given, it is placed in parallel with the lower resistor. The resistor units have to match.
Uout = Uin × Rbottom / (Rtop + Rbottom)
Where the numbers come from
- Input — unit in the field: V
- Upper resistor — unit in the field: Ω
- Lower resistor — unit in the field: Ω
- Load — unit in the field: Ω
Example
12 V, with 2 kΩ on top and 1 kΩ below and no load, gives 4 V. A 1 kΩ load drops the output to 2,4 V.
Questions
Leave the load empty?
Yes, then there is none.
Resistors in kilohms?
Yes, as long as both values and the load use the same units.
Divider current?
You can estimate it on its own: divide the input voltage by the upper resistor plus the lower resistance that results.