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Voltage Divider Calculator

Find a divider's output voltage, or the resistor you need for a target voltage.

  • Free
  • No sign-up
  • Nothing is sent or stored
Solve for
V
Ω
Ω

Result

Output voltage (Vout)
3.83673 V
Divider current
0.816327 mA
Power in R1 / R2
6.66389 mW / 3.13203 mW
Ratio Vout ÷ Vin
0.319728
How it was calculated
  1. Vout = Vin × R2 ÷ (R1 + R2)
  2. = 12 × 4,700 ÷ 14,700
Assumes nothing heavy is connected to the output — a load in parallel with R2 lowers Vout.

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved.

How to use the Voltage Divider Calculator

  1. Choose to solve for the output voltage or R2.
  2. Enter the input voltage and resistor values.
  3. Read the result, current and power in each resistor.

What does this tool do?

Two resistors in series split a voltage in proportion to their values: Vout = Vin × R2 ÷ (R1 + R2). It's a common way to scale a signal down for a microcontroller input.

A divider is only accurate when the load on its output draws much less current than flows through the resistors.

Why use it?

  • Two solve modes.
  • Current and power shown.
  • Load warning.

The formula

Vout = Vin × R2 ÷ (R1 + R2)
R2 = Vout × R1 ÷ (Vin − Vout)

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed by the M2Toolkit team.

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