Voltage Divider Calculator
Output voltage, current and power dissipation of a two-resistor divider.
Results
Output voltage
3.8367
V
Current
0.8163
mA
Power
9.796
mW
Output voltage
3.82451
V
Difference
0.01223
V
What this tool does
A divider is the simplest way to bring a voltage down to something a microcontroller input can read. It only works when almost no current is drawn from the midpoint: connect a real load and the output sags, which is why the current through the pair is shown here too.
Formula
Vout = Vin × R₂ ÷ (R₁ + R₂)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
vin | Input voltage | V |
r1 | Resistance R1 | Ω |
r2 | Resistance R2 | Ω |
rl | Load resistance | Ω |
VO | Output voltage | V |
I | Current | mA |
P | Power | mW |
VL | Output voltage | V |
DV | Difference | V |
Worked example
- Input voltage12 V
- Resistance R110,000 Ω
- Resistance R24700 Ω
- Load resistance1,000,000 Ω
- Output voltage3.8367 V
- Current0.8163 mA
- Power9.796 mW
- Output voltage3.82451 V
- Difference0.01223 V
Limitations
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.