RMS (root mean square) voltage is the DC voltage that would deliver the same heating power. Mains “230 V” is an RMS value – the actual peak is about 325 V.
How to use the RMS Voltage Calculator
- Waveform
- Known value
- Voltage
- DC offset
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the waveform and what you measured, then enter the value and any DC offset.
Inputs explained
| Field | What to enter |
|---|---|
| Waveform | Choose one: Sine, Square, Triangle, Sawtooth … |
| Known value | Choose one: Peak voltage V_p, Peak-to-peak V_pp, Average voltage |
| Voltage | Units: V, mV, kV, µV, MV |
| DC offset | Units: V, mV, kV, µV, MV |
Example values
How the main result changes when Voltage changes and everything else stays at the example values above:
| Voltage (V) | RMS voltage (V) |
|---|---|
| 162.5 | 114.9049 |
| 243.75 | 172.3573 |
| 325 | 229.8097 |
| 406.25 | 287.2621 |
| 487.5 | 344.7146 |
| 650 | 459.6194 |
Formula
Sine: V_rms = V_p/√2 · Square: V_p · Triangle/sawtooth: V_p/√3 · Half-wave: V_p/2 · Full-wave: V_p/√2
With DC offset: V_rms,total = √(V_rms² + V_DC²)
Worked example
Inputs — Waveform: Sine; Known value: Peak voltage V_p; Voltage: 325 V; DC offset: 0 V.
Results — Peak voltage = 325 V; RMS (AC part) = 229.8097 V; RMS voltage = 229.8097 V; Average (rectified) voltage = 206.90143 V; Crest factor = 1.4142.
Key terms
- True RMS
- Measurement correct for any waveform.
Frequently asked questions
What is the RMS of 230 V mains?
230 V is already RMS; the peak is 325 V.
Why use RMS?
It gives the equivalent heating power of DC.
What do cheap multimeters measure?
Average voltage scaled for a sine – wrong for other waveforms.
What is crest factor?
Peak divided by RMS (√2 for a sine).