Total Harmonic Distortion (THD) Calculator

Measure Total Harmonic Distortion to evaluate audio clarity, nonlinear distortion, and clipping behavior in speakers, amplifiers, and full audio systems.

Comma-separated (2nd, 3rd, 4th harmonics)

Total Harmonic Distortion

0.00 %

Distortion Grade
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Signal Purity
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Best Use Case
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How to Use the THD Calculator

This tool calculates total harmonic distortion by comparing unwanted harmonic energy to the original signal. THD is a key indicator of clipping prevention, amplifier linearity, speaker efficiency, and overall dynamic range.

  1. Enter the RMS voltage of the fundamental frequency.
  2. Input RMS voltages of harmonic components generated by the system.
  3. The calculator determines distortion caused by nonlinear speaker behavior, amplifier load stress, impedance effects, and voltage drop.
Formula Used
  • THD (%) = √(V₂² + V₃² + V₄² …) ÷ V₁ × 100
  • V₁ = Fundamental RMS signal
  • V₂…Vn = Harmonic RMS voltages

Who Can Use This Calculator

  • Car audio enthusiasts optimizing amplifier gain and avoiding distortion.
  • Home theater designers analyzing speaker clarity and tonal accuracy.
  • PA system technicians managing high SPL distortion.
  • Speaker designers evaluating enclosure resonance and cone linearity.
  • Audio engineers measuring harmonic distortion during system calibration.

Where THD Analysis Matters

  • Car audio systems with high power subwoofer banks.
  • Home listening rooms sensitive to tonal balance.
  • PA systems operating near amplifier limits.
  • Studios requiring low distortion reference monitoring.
  • Live sound environments prone to clipping and voltage sag.

Additional FAQ

THD below 0.5% is generally considered clean. Below 0.1% is reference-grade audio quality.

Yes. Clipping introduces high-order harmonics, dramatically increasing distortion and risking speaker damage.

Impedance mismatches increase amplifier stress, voltage drop, and nonlinear behavior, raising THD.
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