# Resistor Divider Calculator

The following calculator works out either $$V_{in}$$, $$R_1$$\$, $$R_2$$, or $$V_{out}$$, given the other three parameters, using the resistive voltage divider equation:

$$V_{out}=\frac{R_2}{R_1+R_2}V_{in}$$

where:
$$V_{in}$$ = input voltage
$$R_1$$ = resistance of resistor 1 (see diagram)
$$R_2$$ = resistance of resistor 2 (see diagram)
$$V_{out}$$ = output voltage

It is assumed that the output impedance on $$V_{out}$$ is significantly higher than $$R_2$$ so that it doesn't matter (for example, $$V_{out}$$ is connected to an op-amp input, analogue microcontroller input or similar).

The quiescent current through the divider, $$I_q$$, is also calculated, which can be useful to know when designing power-saving circuits. The equation to find $$I_q$$ is:

$$I_q = \frac{V_{in}}{R_1+R_2}$$

 Variables: Values: Units: Calculate What? Variable Diagram: $$V_{in}$$ $$R_1$$ $$R_2$$ $$V_{out}$$ $$I_q$$

Featured on the Resistors page.