Question 1

How do I convert RMS to peak for a sine wave?

Accepted Answer

For an undistorted sine wave the peak is Vpk = Vrms × √2 ≈ 1.414 × Vrms, and conversely Vrms = Vpk / √2 ≈ 0.707 × Vpk. So a 1 Vpk sine has an RMS of 0.707 V and a peak-to-peak of 2 V.

Question 2

What is the crest factor?

Accepted Answer

Crest factor is the ratio of peak to RMS, Vpk / Vrms. It is √2 ≈ 1.414 for a sine wave, exactly 1 for an ideal square wave, and √3 ≈ 1.732 for a triangle wave. A higher crest factor means sharper peaks relative to the RMS value.

Question 3

Why does the RMS-to-peak conversion depend on the waveform?

Accepted Answer

RMS and average are integrals of the waveform shape, so the ratio to the peak changes with the waveform. A square wave gives Vrms = Vpk, a triangle gives Vrms = Vpk / √3, and a sine gives Vrms = Vpk / √2. Pick the matching waveform before reading the result.

Question 4

What is the difference between dBV and dBu?

Accepted Answer

Both are decibel voltage levels referenced to an RMS voltage. dBV is referenced to 1 V RMS, while dBu is referenced to 0.7746 V RMS — the voltage that delivers 1 mW into 600 Ω. Because of the different references, 0 dBu equals about −2.22 dBV.

Question 5

Is the average value the same as the DC average?

Accepted Answer

No. This tool reports the full-wave rectified average, the mean of the absolute value of the waveform (for a sine that is 2·Vpk/π ≈ 0.6366·Vpk). The true DC average of a symmetric AC waveform is zero, which is why rectified average is used for meter and conversion math.

RMS ↔ PeakCalculator

RMS ↔ Peak
Calculator