Calculators · Waveform conversion

RMS and peak voltage

Live

Convert between RMS, peak, peak-to-peak, and average rectified waveform voltage.

Convert common AC voltage measurements without mental gymnastics.

ConversionUnitsVoltageSignalPower

Inputs

Set the calculator

Enter any one voltage value. The other three update from the selected waveform.

RMS voltage

Peak voltage

Peak-to-peak

Average rectified

Live visual

Calculation cue

Enter valid values to show the live visual.

Calculator guide

RMS and peak voltage formulas and practical checks

Formulas, examples, and practical notes for using the result with confidence.

Overview

One waveform can wear four perfectly valid voltage labels. Peak tells you the tallest excursion, peak-to-peak measures the whole swing, RMS describes heating power, and average rectified voltage describes the average magnitude after the negative half is flipped upright.

Enter any one value and this RMS, peak, peak-to-peak, and average voltage calculator fills in the other three for a sine, square, or triangle wave. The live graph shows why the numbers differ so scope and multimeter readings are easier to compare.

Current example

Enter valid values above and this example will update with the calculator state.

Choose the waveform before trusting the factor

The conversion depends on waveform shape, not just amplitude.

A sine wave, square wave, and triangle wave can share the same peak voltage while having different RMS and average rectified values.

Only use these direct conversions when the waveform shape matches the selected model and has no DC offset. Real waveforms with distortion need measurement or numerical analysis.

Meet the four voltage measurements

Vp, Vpp, Vrms, and average rectified voltage are four different ways to describe the same waveform.

Peak voltage, written as Vp, is the distance from the zero line to the highest point of the waveform. It is the value to check when an op amp input, ADC pin, protection diode, or capacitor rating has an absolute voltage limit.

Peak-to-peak voltage, written as Vpp, is the full swing from the lowest point to the highest point. On a centred waveform with no DC offset, Vpp is twice Vp, which is why oscilloscopes commonly use it for signal amplitude.

RMS voltage, written as Vrms, is the DC-equivalent heating value. If a waveform is applied to a resistor, the RMS value is the voltage you use for power calculations because it produces the same average heating as DC.

Average rectified voltage, often shown as Vavg here, is the average of the waveform after taking its absolute value. It is useful when comparing rectifier behaviour and some older average-responding meter readings, but it is not the same thing as RMS.

Visual clue

How the voltage labels sit on one sine wave

Example: 4 V peak, 8 Vpp, 2.83 Vrms, 2.55 Vavg rectified

Centred waveform swing

V_{pp} = 2 \times V_{p}

Sine RMS from peak

V_{rms} = \frac{V_{p}}{\sqrt{2}}

Sine average rectified

V_{avg} = \frac{2}{π} \times V_{p}

Peak from average rectified sine

V_{p} = \frac{π}{2} \times V_{avg}

Conversion equations by waveform

The selected waveform changes the factors between RMS, peak, peak-to-peak, and average rectified voltage.

For a sine wave, RMS is peak divided by √2, and average rectified voltage is 2 × Vp ÷ π. These are the classic formulas used for mains, audio sine tests, and clean oscillator signals.

For a square wave with equal positive and negative time, RMS, peak, and average rectified voltage are all the same magnitude. Peak-to-peak remains twice the peak value.

For a triangle wave, RMS is peak divided by √3 and average rectified voltage is peak divided by 2. That means triangle waves sit lower than sine waves for the same peak voltage.

Sine wave

V_{rms} = \frac{V_{p}}{\sqrt{2}} V_{avg} = \frac{2}{π} \times V_{p}

Square wave

V_{rms} = V_{p} V_{avg} = V_{p}

Triangle wave

V_{rms} = \frac{V_{p}}{\sqrt{3}} V_{avg} = \frac{V_{p}}{2}

Using meter and oscilloscope readings

Scopes, signal generators, and multimeters often report different voltage types, so the label matters.

Oscilloscopes commonly show peak-to-peak because it is easy to measure the full vertical swing on screen. If you need to check an absolute input rating, convert Vpp to Vp and remember to include any DC offset separately.

Signal generators may be configured in Vpp, Vrms, or amplitude depending on the model. Before comparing a generator setting to a scope reading, confirm whether the load termination is 50 Ω or high impedance, because some generators halve the displayed voltage into a matched load.

Multimeters usually display RMS for AC ranges, but cheaper meters can be average-responding and calibrated for sine waves. A true-RMS meter is still limited by bandwidth and crest factor, so waveform shape and frequency still matter.

Scope Vpp to peak

V_{pp} = 2 \times V_{peak}

Scope reading example

A clean 8 Vpp sine wave with no DC offset has a 4 V peak value, about 2.83 Vrms, and about 2.55 V average rectified.

Square wave example

A centred 5 V peak square wave is 10 Vpp, 5 Vrms, and 5 V average rectified because it spends all its time at the peak magnitude.

Common applications

Use conversions to compare meters, scopes, ADC ranges, and AC signal levels.

This is useful when checking signal generator settings, estimating ADC input swing, comparing audio signal levels, translating oscilloscope readings into RMS power calculations, or checking whether a waveform exceeds an input clamp.

Use Vp for headroom and ratings, Vpp for oscilloscope amplitude, Vrms for heating and power, and average rectified voltage for rectifier or average-responding meter comparisons.

For non-sine waveforms, confirm whether your meter is true RMS and whether it remains accurate at the waveform frequency and crest factor.

Oscilloscope checks

Convert Vpp readings into peak or RMS estimates.

ADC input range

Check whether waveform peaks exceed an ADC or op amp input limit.

AC power estimates

Use RMS voltage with resistance to estimate heating power.

Rectifier checks

Compare average rectified voltage when estimating rectified waveform behaviour before smoothing.

Common mistakes

Conversions fail when waveform shape, offset, or meter behaviour is ignored.

A DC offset changes peak values relative to ground and can change what an ADC or op amp actually sees.

Average voltage can mean different things depending on whether the waveform is rectified. The calculator reports average rectified value for comparison, not the average of a centred AC waveform over a full cycle.

Assumptions and limits

Results are design estimates, not a substitute for datasheets, measurements, safety approvals, or engineering review.
Component tolerance, temperature, supply variation, and real loading can move the final circuit away from the ideal calculation.
Calculator results are estimates for design and learning. Verify values against datasheets, tolerances, temperature, load behaviour, and safety requirements before using them in a real circuit.

Licensing

Calculator copy, equations, and generated visuals are provided for learning and design-reference use on Kobee unless a specific licence is shown.

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