Voltage Divider Calculator
Calculate divider output voltage from input voltage and two resistors.
Interactive Electrical Calculator
Voltage Divider Calculator
Calculate divider output voltage from input voltage and two resistors.
Result
Enter values and calculate.
About the Voltage Divider Calculator
The Voltage Divider Calculator handles component-level calculations for resistors, capacitors and basic AC circuit behavior without needing a spreadsheet, app download or manual lookup table. Calculate divider output voltage from input voltage and two resistors. Component-level calculations like these are used constantly during circuit design, prototyping and troubleshooting, often multiple times within a single build.
It's aimed at electronics hobbyists, students and engineers designing or troubleshooting small circuits, who need a fast, reliable number without redoing the math by hand each time.
How the calculation works
The calculator is built around this relationship:
Vout = Vin × R2 / (R1 + R2).
Where each input maps to a field in the calculator above:
- Input Voltage in V.
- R1 in Ω.
- R2 in Ω.
Change any field above and the result recalculates immediately — nothing is submitted anywhere, so it's safe to experiment freely.
A worked example
For example, start with 12 V for input voltage, 10000 Ω for r1 and 10000 Ω for r2. Those defaults are only a starting point — replace them with your own measured or nameplate values, then press Calculate to get a result specific to your situation.
When to use the Voltage Divider Calculator
Typical reasons people reach for the Voltage Divider Calculator:
- Picking a resistor or capacitor value for a specific circuit target.
- Checking a component combination before ordering parts or building a prototype.
- Working out a circuit's behavior at a specific frequency.
- Verifying a calculated value against a datasheet or standard component range.
Good practice: Reactance is frequency-dependent, so a capacitor or inductor calculation is only valid at the specific frequency it was calculated for.
Also worth knowing: Series and parallel combination rules are opposite for resistors and capacitors, which is a common source of mix-ups when switching between the two.
Frequently asked questions
What does the Voltage Divider Calculator calculate?
Calculate divider output voltage from input voltage and two resistors.
Is the result exact enough to build from?
The formula above is applied exactly to the values you enter, so the math itself is precise. Real-world results can still differ due to component tolerances, temperature, installation method, equipment efficiency and local code requirements, so treat the output as a strong planning estimate and verify final designs against manufacturer data and the electrical code that applies to your installation.
Do I need to sign up or install anything to use it?
No sign-up, download or installation is needed. The Voltage Divider Calculator runs entirely in your browser and is free to use.
Why does this calculation matter in practice?
Reactance, resonance and time-constant calculations explain why a circuit behaves differently at different frequencies, which pure DC thinking does not capture.
What should I do if the result looks off?
The Voltage Divider Calculator works on any modern browser, phone or desktop, and recalculates as soon as you press Calculate. If a result looks off, double-check that every field is filled in with the unit shown next to it (mixing up units, such as W with kW, is the most common cause of an unexpected answer) and re-enter the values.