Voltage Divider Calculator
Unloaded divider Vout = Vin times R2 / (R1 + R2). Informational, not wiring or code approval.
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How to use the voltage divider
- Enter Vin in volts.
- Enter R1 (top) and R2 (bottom) in ohms, and leave Vout blank to solve the tap.
- Or enter Vout and one resistor, and leave the other resistor blank to solve it.
- Read Vout or the missing resistor. Treat the result as an unloaded tap. Nothing is uploaded.
Resistive voltage divider
Unloaded two-resistor tap
| Formula | Vout = Vin * R2 / (R1 + R2) |
|---|---|
| R1 | Resistor from Vin to the output node |
| R2 | Resistor from the output node to ground |
| Current | Vin / (R1 + R2) with no load on the tap |
| Equal resistors | Vout is half of Vin |
| Approval | Informational. Not wiring or code approval. |
What a voltage divider is
Two resistors in series share Vin. The tap across R2 is Vout = Vin times R2 / (R1 + R2). Equal 10 k ohm resistors on 12 V give 6 V. The page also reports the unloaded current through the pair.
Vin, R1, R2, and load
Vin is the source. R1 sits above the tap. R2 sits below it. A real load in parallel with R2 lowers Vout. This page does not model that load. It is the textbook unloaded divider.
How this page computes
Both resistors must be greater than 0. Current is Vin divided by the series sum. The ratio row is R2 / (R1 + R2). The formula runs in this browser.
Limits
No load, no source resistance, no temperature. Informational, not wiring or code approval. CZNull does not receive the values. See the disclaimer.