RMS voltage calculator
Convert between peak, peak-to-peak and RMS voltage for sine, square and triangle waves.
Fill in the fields and the result will appear here automatically.
Convert a positive peak, peak-to-peak or RMS voltage for three symmetric zero-DC waveforms: sine, bipolar 50% square wave and triangle. The mean absolute value is also shown. Arbitrary PWM, unipolar pulses, DC offsets and clipped waveforms are not described by these shape choices.
How it works
Formula and logic
U_RMS=√((1/T)∫u²dt). For peaks±A: U_RMS=A/k and Upp=2 A, where k=√2 for sine, 1 for square and √3 for triangle. Mean|u| is 2 A/π, A and A/2 respectively. RMS mode preserves the entered RMS voltage and derives the other values.
Example
A 311 V sine peak gives 219.91 V RMS, 622 V peak-to-peak and 197.99 V mean|u|. A bipolar square wave with 10 V peak-to-peak gives 5 V RMS. Zero is mathematically possible, but this interface accepts positive voltage for a nonzero signal conversion.
Fields and units
- What is known — list option
- Waveform — list option
- Known voltage — V
How to use
- — Choose the known measure: peak, peak-to-peak or RMS.
- — Choose one of the three symmetric shapes without DC.
- — Enter volts; peak-to-peak is not peak amplitude.
- — Check meter bandwidth, crest factor and AC/DC coupling; the result does not select insulation or capacitor type.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- OpenStax: RMS and active power with cosφ Fluke: average-responding and true-RMS measurement
- Limitation
- Three symmetric zero-DC shapes; not arbitrary PWM, a meter model or insulation selection.
FAQ
How does 220 V RMS relate to sine amplitude?
For a sine A=√2·U_RMS: 220 V RMS corresponds to 311.127 V peak. This is a numerical identity for the specified signal, not a universal mains standard or a complete insulation requirement.
Why does the waveform matter?
RMS depends on shape and DC offset. The listed factors apply to zero-mean sine, symmetric 50% bipolar square and triangle. Unipolar PWM requires different factors.
How do multimeter measurement methods differ?
An average-responding, sine-calibrated meter scales mean|u|. A true-RMS instrument uses an RMS method, but accuracy still depends on bandwidth, crest factor and AC/DC coupling; price alone does not identify the method.
What is peak-to-peak?
Peak-to-peak is max(u)−min(u). For peaks±A it is 2 A. An oscilloscope can display multiple measurements, so check whether its readout is Vpp, peak or RMS.