Calculating your output voltage is straightforward once you know the Voltage Divider formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Voltage Divider Calculator.
What is Voltage Divider?
The Voltage Divider calculation tells you your output voltage from a few simple inputs. The figure you are solving for here is the output voltage.
The Voltage Divider formula
The core formula is:
Output voltage = Input voltage × Resistor R2 ÷ (Resistor R1 + Resistor R2)Here is what each input means:
- Input voltage — a value measured in V. Example: 12 V.
- Resistor R1 — a value measured in Ω. Example: 1,000 Ω.
- Resistor R2 — a value measured in Ω. Example: 2,000 Ω.
How to calculate it step by step
- Write down the input voltage (for example, 12 V).
- Write down the resistor r1 (for example, 1,000 Ω).
- Write down the resistor r2 (for example, 2,000 Ω).
- Apply the formula above to get your output voltage.
- Double-check the result with the Voltage Divider Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Input voltage | 12 V |
| Resistor R1 | 1,000 Ω |
| Resistor R2 | 2,000 Ω |
| Output voltage | 8.000 |
With input voltage of 12 V, resistor r1 of 1,000 Ω and resistor r2 of 2,000 Ω, the output voltage works out to 8.000.
Example 2
With input voltage of 24 V, resistor r1 of 1,000 Ω and resistor r2 of 2,000 Ω, the output voltage works out to 16.000.
| Result | Value |
|---|---|
| Output voltage | 16.000 |
Example 3
With input voltage of 6 V, resistor r1 of 1,000 Ω and resistor r2 of 2,000 Ω, the output voltage works out to 4.000.
| Result | Value |
|---|---|
| Output voltage | 4.000 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Voltage Divider Calculator does it instantly, for free, with the formula and a worked example built in.
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