How to use the voltage divider calculator
Find output voltage of a two-resistor divider. Enter input voltage, top resistor r1, bottom resistor r2 in the fields above; the output voltage, current are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- Vin — Input voltage (V)
- R1 — Top resistor R1 (Ω)
- R2 — Bottom resistor R2 (Ω)
Worked example
With input voltage = 12 V, top resistor r1 = 10000 Ω, bottom resistor r2 = 4700 Ω, the calculator gives output voltage ≈ 3.836735 V; current ≈ 0.8163265 mA.
Frequently asked questions
What is the formula for the voltage divider calculation?
Output voltage (V) = Vin × R2 / (R1+R2). Current (mA) = Vin / (R1+R2) × 1000. Here Vin is input voltage (V), R1 is top resistor r1 (Ω), R2 is bottom resistor r2 (Ω).
What inputs do I need for the voltage divider calculator?
You need input voltage in V, top resistor r1 in Ω, bottom resistor r2 in Ω. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.