Q-factor and Frequency Ranges for EQ
I believe the standard is 1/3 octave, or a Q of about 4.3.
For a thorough discussion of Q and ripple see https://www.ranecommercial.com/legacy/note101.html

One octave is a doubling of frequency; therefore a bandpass filter with passband boundary frequencies f1 and f2 of, say, 100 Hz and 200 Hz respectively, is said to be one octave wide. One-third octave is a 26% increase in frequency (21/3 = 1.26); therefore, boundary frequencies of 100 Hz and 126 Hz respectively would be 1/3-octave wide.

and

The Quality Factor, or &quot;Q&quot;, of a filter is a close relative to bandwidth. It is defined to be the center frequency divided by the bandwidth in Hertz. For example, a filter centered at 1000 Hz that is 1/3-octave wide has -3dB frequencies located at 891 Hz and 1123 Hz respectively, yielding a bandwidth of 232 Hz. Q, therefore, is 1000 Hz divided by 232 Hz, or 4.31.

To calculate Q from bandwidth, see http://www.sengpielaudio.com/calculator-bandwidth.htm