Good power sources keep their voltage steady as load changes. Voltage regulation measures how much the output sags from no load to full load – a few percent for a good transformer, near zero for an electronic regulator.
How to use the Voltage Regulation Calculator
- No-load voltage V_NL
- Full-load voltage V_FL
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the output voltage with no load and at full load.
Inputs explained
| Field | What to enter |
|---|---|
| No-load voltage V_NL | Units: V, kV, mV |
| Full-load voltage V_FL | Units: V, kV, mV |
What each result means
- Voltage regulation = ([No-load voltage V_NL] – [Full-load voltage V_FL])÷[Full-load voltage V_FL]×100
- Voltage drop = [No-load voltage V_NL] – [Full-load voltage V_FL]
Example values
How the main result changes when No-load voltage V_NL changes and everything else stays at the example values above:
| No-load voltage V_NL (V) | Voltage regulation (%) |
|---|---|
| 120 | -47.8261 |
| 180 | -21.7391 |
| 240 | 4.3478 |
| 300 | 30.4348 |
| 360 | 56.5217 |
| 480 | 108.6957 |
Formula
Regulation (%) = (V_NL − V_FL) / V_FL × 100
Worked example
Inputs — No-load voltage V_NL: 240 V; Full-load voltage V_FL: 230 V.
Results — Voltage regulation = 4.3478 %; Voltage drop = 10 V.
Key terms
- Full load
- The rated maximum load.
Frequently asked questions
What is good regulation?
2–5% for distribution transformers; under 1% for regulated supplies.
Why does voltage drop under load?
Winding resistance and leakage reactance.
Can regulation be negative?
Yes, with capacitive loads.
Lower or higher is better?
Lower – the voltage changes less.