How this calculator works
Voltage regulation compares a supply's no-load output with its output under a specified load. Two denominator conventions give different percentages even for the same measurements. Both are shown explicitly to avoid mixing them. Negative regulation is possible when loaded voltage exceeds no-load voltage. The result describes only the entered operating points, not transient response or all power factors.
Formula
rdown = (Vno-Vfull)/Vfull; rup = (Vno-Vfull)/Vno. Vno = Vfull(1+rdown) = Vfull/(1-rup).
Worked example
No-load 110 V and full-load 100 V give 10% using full-load voltage, or 9.090909% using no-load voltage. A 200 V full-load output with 5% full-load-referenced regulation has 210 V no-load output.
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Frequently asked questions
Which convention should I use?
Use the denominator specified by the equipment standard or source. This page labels both explicitly.
Can regulation be negative?
Yes. Some operating conditions produce a higher voltage under load.
Is voltage regulation the same as regulator efficiency?
No. Regulation measures voltage change; efficiency compares output and input power.