Enter Vin, R1, and R2. The schematic and output values update in real time. A loading-effect warning tells you when your load impedance might pull Vout off-target.
Vout = Vin · R2 / (R1 + R2). The output voltage is a fraction of the input, determined by the ratio of R2 to the total resistance.
Watch out for loading effects. The formula assumes nothing is drawing current from Vout. If you connect a load with resistance comparable to R2, it shunts current to ground and Vout drops below the calculated value. As a rule: load resistance should be at least 10× R2.
For dividers driving a high-impedance input (like an ADC or op-amp), this rule is easy to satisfy. For dividers driving anything that draws real current, use a buffer (op-amp follower) instead.