Voltage divider calculator
Bring a voltage down with two resistors: enter three of the input, R1, R2 and the output, and get the fourth.
3.33 V
- Input
- 5 V
- R1
- 1 kΩ
- R2
- 2 kΩ
- Output
- 3.33 V
- Current
- 1.67 mA
The formulas
| To find | Formula |
|---|---|
| Output | Vçıkış = Vgiriş × R2 ÷ (R1 + R2) |
| R1 | R1 = R2 × (Vgiriş − Vçıkış) ÷ Vçıkış |
| R2 | R2 = R1 × Vçıkış ÷ (Vgiriş − Vçıkış) |
Where it is used
An Arduino Uno talks at 5 V; an ESP32, an HC-05's RX pin and many sensors want 3.3 V. The 5 V from the Uno's TX comes down to 3.33 V through 1 kΩ (R1) and 2 kΩ (R2). To read a 12 V battery on an analog input, 10 kΩ and 4.7 kΩ bring 12 V down to 3.84 V; multiply the reading by 14.7 ÷ 4.7. A divider is only for an input that draws almost no current: whatever is on the output draws current too and pulls the voltage down. To power a module or a motor, use a voltage regulator.
In the app, tick off every wire, match the parts to your inventory and pick up where you left off.
