Electrical Calculations: Ohm's Law and Circuits Explained
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Voltage Divider Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Output voltage
8.000
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Voltage Divider Calculator
The Voltage Divider Calculator works out your output voltage in an instant. Enter input voltage, resistor r1 and resistor r2 and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the input voltage.
- Enter the resistor r1.
- Enter the resistor r2.
- Read off your output voltage — the calculator updates automatically, with no button to press.
Formula
The Voltage Divider Calculator uses the formula:
Output voltage = Input voltage × Resistor R2 ÷ (Resistor R1 + Resistor R2)
Worked example
For example, with input voltage of 12 V, resistor r1 of 1,000 Ω and resistor r2 of 2,000 Ω, the output voltage is 8.000.
| Input voltage | 12 V |
|---|---|
| Resistor R1 | 1,000 Ω |
| Resistor R2 | 2,000 Ω |
| Output voltage | 8.000 |
|---|
Results are estimates for educational use, not professional advice.
Frequently asked questions
Two resistors in series split the input voltage. The output across R2 is Vin × R2 ÷ (R1 + R2). For 12 V with 1k and 2k it is 8 V.
It provides a reference voltage, scales a signal down for measurement, or biases a circuit. It is one of the most common building blocks in electronics.
Yes. Connecting a load across R2 lowers the output. For accurate results, the load resistance should be much larger than R2.
Choose the resistor ratio so R2 ÷ (R1 + R2) equals the fraction of Vin you want. Adjust R1 and R2 and check the output here.
The Voltage Divider Calculator uses the formula: Output voltage = Input voltage × Resistor R2 ÷ (Resistor R1 + Resistor R2). For example, with input voltage of 12 V, resistor r1 of 1,000 Ω and resistor r2 of 2,000 Ω, the output voltage is 8.000.
Enter the input voltage. Enter the resistor r1. Enter the resistor r2. Read off your output voltage — the calculator updates automatically, with no button to press.
Related guides
Voltage Divider Table: Output voltage by Input voltage
Reference table of output voltage for Voltage Divider across a range of input voltage values — exact, engine-computed figures you can read off at a glance.
How to Calculate Voltage Divider: Formula, Steps & Examples
Learn how to calculate Voltage Divider — the formula explained step by step, with worked examples and a free calculator to check your answer.