RMS, Peak & Peak-to-Peak
Convert RMS, peak, peak-to-peak and average for sine, square, triangle, rectified and pulse waveforms with crest and form factor, or true RMS of pasted samples.
All four measures of the waveform from the one you know, its crest factor and form factor, the RMS with a DC offset, and for pasted samples the true RMS, mean, AC component and extremes.
Example: A 325 V peak sine is 230 V rms and 650 V peak-to-peak (crest factor 1.414); a 10 V peak triangle is 5.77 V rms; a 5 V pulse at 25 % duty is 2.5 V rms, 1.25 V average; a sampled sine gives 0.707.
Shape factors,
or the real thing from samples.
What RMS means, where the factors for each waveform come from, and how sampled values are handled.
RMS
The root-mean-square value of a waveform is the DC level that would deliver the same power into a resistor: square the signal, average over a period, take the root. For a sine the RMS is the peak ÷ √2 (0.707), which is why 230 V mains has a 325 V peak. The average of the rectified signal is a different quantity — 2/π (0.637) of the peak for a sine — and is what a cheap meter actually measures before scaling it by 1.11 to display "RMS", a scaling that is only right for sine waves.
The waveforms
Each shape has fixed ratios: square (50 %) RMS = peak; triangle and sawtooth RMS = peak ÷ √3 (0.577), average = peak ÷ 2; half-wave rectified sine RMS = peak ÷ 2, average = peak ÷ π; full-wave rectified sine keeps the sine's RMS and average; a pulse train from 0 to the peak has RMS = peak·√(duty) and average = peak·duty. Crest factor is peak ÷ RMS, form factor RMS ÷ average. A DC offset adds in quadrature: RMS_total = √(RMS_ac² + DC²).
Samples
Paste values sampled evenly over whole periods and the page computes the true RMS √(Σv²/n), the mean (DC) and the AC component √(RMS² − mean²), with the extremes. Uneven spacing or a fraction of a period biases the result; for arbitrary waveforms that is the only honest method — no shape factor applies. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Sine RMS = peak/√2, average = 2·peak/π; square RMS = peak; triangle RMS = peak/√3; half-wave rectified RMS = peak/2; pulse RMS = peak·√duty; true RMS = √(Σv²/n); RMS with offset = √(RMS² + DC²)
Last reviewed 22 September 2026. How results are checked: How we verify.