Voltage Divider Calculator

What this calculator does

The Voltage Divider Calculator provides fast estimates using standard electrical relationships. Enter Input Voltage (Vin), Resistor R1, Resistor R2 to compute results for real-world electrical scenarios. Use it for quick checks, comparisons, and documentation while planning.

Inputs explained

  • Input Voltage (Vin): The source voltage in Volts.
  • Resistor R1: Value used by the calculator.
  • Resistor R2: Value used by the calculator.

How it works / Method

The calculator applies the listed formulas to the values you enter and then formats the result in standard units.

Formulas used

  • Vout = Vin x R2 / (R1+R2)

Units: V in volts (V)

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Voltage Divider Calculator

Calculate output voltage or resistor values

V
Ω
Ω
Result
—

Formula

VoutVout = Vin × R2 ÷ (R1+R2)

Circuit Diagram

    Vin ──┬── R1 ──┬── GND
          │        │
          │       Vout
          │        │
          └── R2 ──┘

Related

Ohm's LawVolts to Amps

Step-by-step example

Scenario: Divide 12V with R1=10kΩ and R2=20kΩ.

Formula: Vout = Vin x R2 / (R1 + R2)

  1. Vout = 12 x 20000 / (10000 + 20000)
  2. Vout = 240000 / 30000
  3. Vout = 8V

Result: 8 Volts output

Use cases

  • Split voltage or current in simple resistor networks.
  • Estimate branch values in parallel paths.
  • Check divider ratios during circuit design.
  • Validate hand calculations for homework or labs.

Assumptions & limitations

  • Results are estimates and may be rounded; small differences are expected.
  • Inputs assume steady-state values; transient and surge effects are not modeled.
  • Voltage can vary by supply, load, and location; use measured values when possible.
  • Power factor varies by load type; use a realistic value for inductive equipment.
  • Wiring rules and safety codes vary by jurisdiction; consult a licensed electrician for installation decisions.

Sources & references

Related calculators

Frequently Asked Questions

The Voltage Divider Calculator solves basic resistor network relationships. It estimates voltage or current in divider configurations. Enter known values and it returns the missing result. This tool is for quick checks and education. Use simulation for complex networks or heavy loading. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Divider calculations use Ohm's law and series or parallel relationships. Voltage dividers depend on resistance ratios. Current dividers depend on inverse resistance ratios. The calculator applies these directly to your inputs. Use consistent units to avoid scaling errors. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Yes, a load changes the effective resistance. That shifts the divider ratio and output value. Include the load resistance if it is known. If loading is significant, simulate the full circuit. This calculator assumes ideal loading unless specified. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Resistor tolerance directly affects divider ratios. A 1% mismatch can still create noticeable error. Use tight tolerance resistors for precision work. Measure actual values if accuracy matters. The calculator uses nominal values only. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Results follow ideal circuit equations. Temperature, tolerance, and loading change real outputs. Use this tool for planning and sanity checks. Validate with measurement when accuracy is critical. Assume small error margins in real builds. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Use it for quick checks and early design work. Final designs should include loading and tolerance analysis. A full circuit model provides better accuracy. Check component ratings and limits separately. Consult a professional for safety-critical designs. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.