What is Q factor in EQ?

Q (quality factor) defines the width of an EQ band. A higher Q means a narrower, more surgical cut or boost. A lower Q means a wider, more gentle shape. Q = centre frequency / bandwidth. A Q of 1.41 is approximately 1 octave wide, Q of 4.32 is 1/3 octave.

What Q should I use for mixing?

For broad tonal shaping: Q 0.5-1.5 (1-2 octaves). For corrective EQ: Q 2-8 (narrow cuts). For notch filtering: Q 10-30 (very narrow). Low Q values sound more natural and musical, high Q values are surgical but can sound unnatural if overused.

How do octave width and Q relate?

They are inversely related — wider bandwidth (more octaves) means lower Q. 1/3 octave = Q 4.32, 2/3 octave = Q 2.14, 1 octave = Q 1.41, 2 octaves = Q 0.67. The exact conversion uses: Q = sqrt(2^N) / (2^N - 1) where N is octaves.

What is the bandwidth of a parametric EQ band?

Bandwidth is the frequency range between the -3 dB points either side of the centre frequency. For a 1 kHz centre with Q of 1.41: bandwidth = 1000/1.41 = 709 Hz, spanning from about 707 Hz to 1414 Hz (one octave).

AudioCalcs

EQ Frequency Calculator — Q Factor & Bandwidth Converter

Find EQ centre frequency, bandwidth and Q factor. Convert between octave width and Q.

Conversion Mode

Centre Frequency

Q Factor

How We Calculate This

Q to Octave Width

Octaves = (2 / ln2) × asinh(1 / (2Q))

Octave Width to Q

Q = sqrt(2^N) / (2^N − 1) where N = octave width

Frequency Bounds

f_lower = f_centre / 2^(N/2)

f_upper = f_centre × 2^(N/2)

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.