Sine wave
| V_peak | Amplitude of the waveform |
|---|---|
| V_pp | = 2 · V_peak (peak-to-peak) |
| V_avg (abs) | ≈ 0.637 · V_peak |
| V_RMS | = V_peak / √2 ≈ 0.707 · V_peak |
| Crest factor | = V_peak / V_RMS = √2 ≈ 1.414 |
| Form factor | = V_RMS / V_avg ≈ 1.11 |
Common waveforms
| Waveform | V_RMS / V_peak | V_avg / V_peak | Crest factor |
|---|---|---|---|
| Sine | 0.707 (1/√2) | 0.637 (2/π) | 1.414 |
| Full-wave rect. | 0.707 | 0.637 | 1.414 |
| Half-wave rect. | 0.500 | 0.318 | 2.000 |
| Square | 1.000 | 1.000 | 1.000 |
| Triangle | 0.577 (1/√3) | 0.500 | 1.732 |
| Sawtooth | 0.577 | 0.500 | 1.732 |
| White noise | — | — | ~3.0–4.0 |
Mains examples
| 120 V RMS (US) | V_peak ≈ 170 V, V_pp ≈ 340 V |
|---|---|
| 230 V RMS (EU) | V_peak ≈ 325 V, V_pp ≈ 650 V |
| 277 V RMS (US industrial) | V_peak ≈ 392 V |
Notes
- RMS is the DC-equivalent heating value: an RMS current through a resistor dissipates the same average power as that DC value.
- Only true-RMS meters report correct RMS on non-sinusoidal signals (PWM, dimmers, switching supplies).
Was this article helpful?