Electronics
RMS Voltage & Current Calculator
Enter a peak voltage or current and pick the waveform shape to get the RMS value, the rectified average, and the peak-to-peak swing.
Convert a peak sine, square, or triangle waveform value to RMS and average.
RMS by waveform shape
Sine: V_rms = V_peak/√2 Square: V_rms = V_peak Triangle: V_rms = V_peak/√3
RMS (root mean square) is the equivalent DC value that would deliver the same average power. Each waveform shape has a fixed ratio between its peak and RMS value, which is why the multiplier changes with the waveform you pick.
How to use
- Read the peak value off your source, datasheet, or oscilloscope — make sure it's peak, not peak-to-peak.
- Pick the waveform shape that matches your signal; mains power and most AC sources are sine waves.
- Use the RMS value for power calculations and the average value when you're specifically working with a rectified/filtered signal.
Example
Input: 170V peak, sine wave
Output: RMS ≈ 120.2 V, average ≈ 108.2 V, peak-to-peak = 340 V
Student-friendly breakdown
This walkthrough emphasizes the most searched ideas for RMS Voltage & Current Calculator: rms voltage calculator, peak to rms calculator, rms current calculator. Start with the formula above, then follow the guided steps to double-check your work. For quick revision, highlight the givens, plug into the equation, and finish by verifying your units.
Need more support? Use the links below to open the long-form guide, browse additional examples, or hop into adjacent calculators within the same topic — each one is a quick way to double-check your work or handle a related question without starting from scratch.
Deep dive & study plan
RMS Voltage & Current Calculator: Converts a peak sine, square, or triangle waveform value to RMS and average. It's built around rms voltage calculator, rms calculator, peak to rms calculator, so you can go from a raw question to a checked answer without switching tools.
The math behind it: RMS (root mean square) is the equivalent DC value that would deliver the same average power. Each waveform shape has a fixed ratio between its peak and RMS value, which is why the multiplier changes with the waveform you pick. The core relationship is Sine: V_rms = V_peak/√2 Square: V_rms = V_peak Triangle: V_rms = V_peak/√3, shown above the calculator so you can see exactly how your inputs turn into the result.
To use it well: (1) Read the peak value off your source, datasheet, or oscilloscope — make sure it's peak, not peak-to-peak. (2) Pick the waveform shape that matches your signal; mains power and most AC sources are sine waves. (3) Use the RMS value for power calculations and the average value when you're specifically working with a rectified/filtered signal. Keep your units consistent as you go, and re-run a case you already know the answer to — it's the fastest way to catch a typo before it throws off a result you're relying on.
Worked example: entering 170V peak, sine wave returns RMS ≈ 120.2 V, average ≈ 108.2 V, peak-to-peak = 340 V. Try swapping in your own numbers next, especially a case you're unsure about, before you use this for something that matters.
Quick retention checklist
- Speak the formula aloud (or annotate it) so the relationships stick.
- Write each step in your own words and compare with the numbered list above.
- Swap in new numbers for the Example to make sure the calculator (and your logic) handles edge cases.
- Check at least one related calculator below — it's the fastest way to confirm your numbers still line up from a different angle.
FAQ & notes
Why does US mains power quote 120V but the peak is 170V?
120V is the RMS value — the number that matters for power delivery and what's printed on outlets and appliances. The actual voltage swings between +170V and -170V on a sine wave, which is exactly the example above.
Why is a square wave's RMS equal to its peak?
A square wave spends 100% of its time at either +peak or -peak with no time in between, so its average power is identical to a DC source at that peak value — there's no time-averaging effect the way there is with a sine or triangle wave.
What formula does the RMS Voltage & Current Calculator use?
RMS (root mean square) is the equivalent DC value that would deliver the same average power. Each waveform shape has a fixed ratio between its peak and RMS value, which is why the multiplier changes with the waveform you pick.
How do I use the RMS Voltage & Current Calculator?
Read the peak value off your source, datasheet, or oscilloscope — make sure it's peak, not peak-to-peak. Pick the waveform shape that matches your signal; mains power and most AC sources are sine waves. Use the RMS value for power calculations and the average value when you're specifically working with a rectified/filtered signal.