THD converter
Convert distortion between percent and decibels, and see what bit depth would give the same noise.
That's 10× as clean as a good hi-fi amplifier, while the edge of audibility is 5× worse. That is about -60 dB.
What it means
How clean is that?
A single THD number hides which harmonics are present. Low-order distortion is far less audible than the same amount of high-order.
Every unit
Your distortion in every unit
Learn
Three things worth knowing
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0.01% = −80 dB
Every factor of ten in percent is 20 dB. 1% is −40 dB, 0.1% is −60, 0.001% is −100.
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Bits set a floor
Each bit of resolution is about 6 dB, so 16-bit audio bottoms out near −98 dB. A converter cannot be cleaner than its own quantization.
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Numbers are not audibility
A valve amplifier at 1% can sound better than a transistor one at 0.01%, because the harmonics it adds are low-order and even. THD alone does not say what it sounds like.
Shortcuts
Popular distortion conversions
Background
About THD
Total harmonic distortion is the size of everything an amplifier adds, as a fraction of the signal. Analog specifications quote percent; digital ones quote decibels, and −80 dB is 0.01%.
The audible threshold for most program material is somewhere near 0.5%, which is why 0.001% specifications are about engineering pride rather than hearing.