# RMS Voltage Calculator

URL: https://speedycalculator.com/calculators/physics/rms-voltage/
Last updated: 2026-10-30

> The RMS voltage calculator converts peak, peak-to-peak or average voltage into RMS for sine, square, triangle, sawtooth and half- or full-wave rectified waveforms, including a DC offset.

## Inputs

- Waveform
- Known value
- Voltage (V, mV, kV, µV, MV)
- DC offset (V, mV, kV, µV, MV)

## Results

- Peak voltage
- RMS (AC part)
- RMS voltage
- Average (rectified) voltage
- Crest factor

## 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)
```

## Explanation

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

FieldWhat to enterWaveformChoose one: Sine, Square, Triangle, Sawtooth …Known valueChoose one: Peak voltage V_p, Peak-to-peak V_pp, Average voltageVoltageUnits: V, mV, kV, µV, MVDC offsetUnits: 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)162.5114.9049243.75172.3573325229.8097406.25287.2621487.5344.7146650459.6194

## 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.

## FAQ

**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).


## Sources

- [OpenStax – University Physics Volume 2](https://openstax.org/details/books/university-physics-volume-2)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)