Electronics
Voltage divider calculator
Vin, R1 and R2 → output voltage Vout and divider current.
- Instant
- Free
- Private (processed locally)
- No sign-up
Calculate a voltage divider
Enter the input voltage Vin and resistors R1 and R2. The tool computes the output voltage Vout (across R2) and the divider current.
The formulas
- Vout = Vin × R2 / (R1 + R2)
- I = Vin / (R1 + R2)
- Vout measured across R2
- With no output load
Example
| Input | Value |
|---|---|
| Vin / R1 / R2 | 12 V / 1 kΩ / 2 kΩ |
| Vout | 8 V |
| Current | 4 mA |
100% local calculation, no data sent.
Frequently asked questions
What is the voltage divider formula?
Vout = Vin × R2 / (R1 + R2), with Vout measured across R2.
How do I compute the current?
I = Vin / (R1 + R2). It is the current flowing through the R1-R2 chain (with no output load).
Does an output load change Vout?
Yes: a load in parallel with R2 lowers Vout. For an accurate calculation its resistance should be large compared to R2.
What is a voltage divider for?
To get a reference voltage, read a resistive sensor, or scale a signal to an ADC input.