Voltage Divider Calculator
Two-resistor tap math — not a loaded ADC front-end model. Click any i for detail.
Divider
Vin (V)
i
Vin
Voltage across the whole divider. |
|
|---|---|
R1 (Ω)
i
R1
Resistor from Vin to the tap. |
|
R2 (Ω)
i
R2
Resistor from the tap to ground (reference). |
How to use this calculator
- Enter Vin.
- Enter R1 (top) and R2 (bottom).
- Read Vout and the current through the pair.
- If something loads the tap, Vout will sag — not modeled.
Results explained
Unloaded: Vout = Vin × R2 / (R1 + R2). Current = Vin / (R1 + R2). Ohm’s law is the single-resistor cousin.
Quick reference: dividers
Equal resistors give Vout = Vin / 2.
| Item | Detail |
|---|---|
| 10k / 10k @ 12 V | 6 V |
| Loaded tap | Not in this formula |
| Ohm’s law | V = I R |
| Voltage drop on a run | Voltage drop calculator |
Use the same units for both resistors (ohms throughout).
How the estimate is built
Vout = Vin × R2 / (R1 + R2).
Example scenario
12 V, 10 kΩ and 10 kΩ → 6.00 V.
FAQ
Which resistor is R2?
The one from tap to ground in this page’s convention.
Potentiometer?
Treat the wiper split as R1 and R2.
AC divider?
This is a DC / resistive sketch.