Peak Voltage Calculator
Find peak voltage from RMS or peak-to-peak on a sinusoidal wave. Vpeak = Vrms × √2. The default 120 V RMS is about 169.7 V peak. Informational, not wiring approval.
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How to use the peak voltage calculator
- Enter RMS voltage, or peak, or peak-to-peak. Leave the unknown blank.
- The page assumes a symmetric sine centered on zero.
- Read peak, RMS, and peak-to-peak together.
- Use the figures for study or quick checks. Nothing is uploaded.
Peak voltage
Sinusoidal maximum above zero
| Peak | Maximum instantaneous voltage on a sine |
|---|---|
| RMS | Vrms = Vpeak / √2 on a pure sine |
| Peak-to-peak | Vpp = 2 × Vpeak when centered |
| 120 V example | US nominal RMS maps to about 170 V peak |
| Measurement | Scopes often read peak or Vpp directly |
| Approval | Informational. Not wiring or code approval. |
Peak from RMS
Vpeak = Vrms × √2. With 120 V RMS the peak is about 169.706 V. Peak-to-peak doubles that to about 339.4 V on a centered sine. This is the amplitude above the zero crossing, not line-to-line unless you typed a line-to-line RMS value.
Scope and crest factor
Crest factor is peak divided by RMS. A sine has crest factor √2. Distorted mains can exceed that. This page keeps the ideal sine model so the factor stays √2.
Peak vs working voltage labels
Capacitor voltage ratings and surge labels sometimes cite peak or DC working levels. Do not assume this arithmetic replaces datasheet limits or code rules for clearance and insulation.
Limits
Single-frequency sine only. DC offset, clipping, and multi-tone waveforms are out of scope.
The formula runs in this tab. CZNull does not receive the numbers.
Informational only. Not wiring, code, or manufacturer approval. See the disclaimer.