About The Harmonic Distortion THD Calculator

The Harmonic Distortion THD Calculator computes total harmonic distortion, total RMS, and distortion factor from a fundamental magnitude and harmonic magnitudes.

How to Use the THD Calculator Online

1. Enter the fundamental voltage or current magnitude.
2. Paste harmonic magnitudes separated by commas, spaces, or new lines.
3. Run the calculator to review THD percentage and total RMS.

Choosing Options Correctly

Use magnitudes in the same units and from the same measurement method. The tool expects harmonic magnitudes, not percentages, and it does not perform live waveform sampling or FFT analysis.

Common Use Cases

• Check THD from analyzer harmonic readings.
• Compare distortion before and after filtering.
• Validate quick power-quality calculations.

Quick FAQ

Can I mix volts and amps?
No. Harmonic components must all be the same quantity and unit, such as all volts or all amps.

Does this measure live THD?
No. It calculates from values you enter; it does not connect to meters or measure a live waveform.

Should the fundamental be included?
Enter the fundamental separately where the tool asks for it, then enter harmonic magnitudes consistently.

Can I use it for power-quality compliance?
Use it for quick checks only. Compliance work needs calibrated measurements, the correct standard, time windows, and loading conditions.