Last updated October 13, 2026 · Report an error
A sine wave's voltage can be described four different ways — peak, peak-to-peak, RMS, and average — each useful in different contexts. This tool converts between all four, given any one of them.
How it works
Choose which value you know (peak, peak-to-peak, RMS, or average) and enter it. The calculator finds the peak voltage first, then derives the other three using the fixed ratios that apply specifically to a pure sine wave: Vpp = 2·Vpeak, Vrms = Vpeak/√2, Vavg = (2/π)·Vpeak.
- Enter what value do you know?.
- Enter value (V).
- Click Calculate to see your results.
Examples
Mains-like voltage
A sine wave with a 10V peak has a 20V peak-to-peak value, about 7.07V RMS, and about 6.37V average — these ratios hold for any pure sine wave, regardless of its actual amplitude.
Who should use it
- Electronics and electrical engineering coursework on AC signals.
- Converting between spec-sheet values (often peak) and measured or design values (often RMS).
Industry applications
- Electronics and electrical engineering
- Power systems and AC circuit analysis
Advantages
- Converts freely between all four common ways of expressing sine wave voltage.
- Uses the standard, well-established sine-wave ratios.
Limitations
- Only valid for a pure sine wave — a different waveform shape needs different ratios entirely.
Common mistakes to avoid
- Applying these sine-wave-specific ratios to a non-sinusoidal signal (square, triangle, sawtooth, etc.) — use the Crest Factor Calculator with actual measured values for those instead.
- Confusing peak with peak-to-peak — peak-to-peak is exactly double the peak for a symmetric sine wave.
Best practices
- Confirm your signal is genuinely a pure sine wave before relying on these fixed ratios — many real-world signals (like rectified or clipped waveforms) are not.
- Use RMS values for power/heating calculations, and peak values for checking component voltage ratings/breakdown limits.
Tips
- If you're not sure whether your signal is a true sine wave, use the Crest Factor Calculator with your actual measured peak and RMS values — a result far from √2 ≈ 1.414 tells you it isn't.
Frequently asked questions
Yes, with no signup and no limit on how many conversions you run.
RMS (root mean square) voltage is the value that produces the same heating/power effect in a resistor as an equivalent DC voltage — it's why household AC voltage is quoted as an RMS figure, not a peak figure.
No — these specific ratios (2, 1/√2, 2/π) only hold for a pure sine wave. A square wave, triangle wave, or any other shape has different, genuinely different ratios between its peak, RMS, and average values.
It's the average of the absolute value (rectified) of the waveform over one cycle — the plain average of an unrectified sine wave would be zero, since it's symmetric above and below zero.