Enter a peak or RMS voltage to calculate the peak-to-peak voltage of a sine wave.
How to Use the Peak-to-Peak Voltage Calculator
Switch the toggle to "From Peak" or "From RMS" to match whichever number's already known, type it in, and the peak-to-peak figure follows immediately — this is a sine-wave calculation throughout, so the constants below don't hold for other waveform shapes.
From peak: Vpp = 2 × Vpeak
From RMS: Vpp = 2√2 × VrmsPeak-to-peak is the full vertical distance an oscilloscope trace covers in one cycle — from the lowest point of the negative swing to the highest point of the positive one — which is why scope measurements are so often reported this way rather than as RMS: it's the number a screen grid literally shows without any averaging math applied first.
A 120 V RMS mains supply works out to roughly 339.4 V peak-to-peak — over 2.8 times the RMS figure most people associate with "120 volts," which catches people off guard the first time they see a scope trace of a household outlet. That's 2√2 ≈ 2.828, the combined factor of doubling the peak (to cover both halves of the swing) and converting RMS to peak in the first place.
Already have a peak voltage rather than RMS? The Peak Voltage calculator runs the opposite direction, and the RMS Voltage calculator converts either one down to the RMS figure a multimeter would show.