Voltage divider calculator

Find the output voltage, current and power of a two-resistor divider.

Schematic

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Results

Output voltage2.5 V50% of input voltage

Voltage divider results
Divider current	250 µA

Advanced results

Advanced voltage divider results
Total resistance	20 kΩ
Voltage across R1	2.5 V
Voltage across R2	2.5 V
Power in R1	625 µW
Power in R2	625 µW

How a voltage divider works

Two resistors in series divide an input voltage. The output is taken from their junction, measured relative to ground. R1 connects the input to the output; R2 connects the output to ground.

Vout = Vin × R2 / (R1 + R2)

Vin and Vout are in volts. R1 and R2 are in ohms. Divider current is I = Vin / (R1 + R2), and each resistor dissipates P = I²R.

For a single resistor, use the Ohm’s law and power calculator.

Do the math

Selected input values
Vin	5 V
R1	10 kΩ
R2	10 kΩ

Output voltage: $V_{\mathrm{out}} = V_{\mathrm{in}} \times \frac{R_2}{R_1 + R_2}$
$= 5\,\mathrm{V} \times \frac{10\,\mathrm{k\Omega}}{10\,\mathrm{k\Omega} + 10\,\mathrm{k\Omega}}$
≈ 2.5 V
Divider current: $I = \frac{V_{\mathrm{in}}}{R_1 + R_2}$
$= \frac{5\,\mathrm{V}}{10\,\mathrm{k\Omega} + 10\,\mathrm{k\Omega}}$
≈ 250 µA
Power in R1: $P_1 = I^2 \times R_1$
$= \left(250\,\mathrm{\mu A}\right)^2 \times 10\,\mathrm{k\Omega}$
≈ 625 µW
Power in R2: $P_2 = I^2 \times R_2$
$= \left(250\,\mathrm{\mu A}\right)^2 \times 10\,\mathrm{k\Omega}$
≈ 625 µW

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Voltage divider calculator

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How a voltage divider works

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Ohm’s law & power

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