Yes, they double in frequency for each step. Seems like 10band eq's tend to start at 32hz and double through to 16k

Like this:

It's also nice to have a chart like this to put it in perspective:

If you can't make that out here is the link . So actually those frequencies are between B and C for most octaves.

If you do an image search for 31 band eq you will find a load of pictures of hardware eq's with the frequency bands marked on them.

The standard ISO for a 31 band Eq is as follows HZ:20/25/31.5/40/50/63/80/100/125/160/200/250/315/400/500/630/800/1K/1.25K/1.6K/ 2K/ 2.5K/3.15K/4K/5K/6.3K/8K/10K/12.5K/16K/20K.

But I think that this wasn’t the question, the question was how to calculate it, right?

First, every octave doubles or divides per two a chosen frequency.

Let’s take as a reference 400 Hz, the upper octave of this frequency is 800, and the lower 200. Let’s assume that you want a 1/3 octave Eq: 800Hz-400Hz=400Hz;

Then 400Hz/3 = 133.33^Hz This means that the frequencies would be: 400/ 533.33^ (400+133.33^)/ 666.66^ (400+133.33^x2)/ 799.99^ (400+133.33^x3)

And for the lower octave 400-200=200; 200/3=66.66^; So: 200/ 266.66/333.3266/399.99

Notice that standard ISO has rounded those numbers 200/250/315/400

If you want an 1/12 octave for the frequencies among 400 and 800, then 400/12=33.33^ Then: 400/433.33^/466.66^/etc. and then rounded.

Notice also that the upper octave of 16K is 32K, so out of human range. I hope it helps. Regards.

An octave is a 2:1 ratio between frequencies (doubling). I think you'll find that a 10-band EQ uses bands (frequencies) an octave apart. A 31-band EQ uses bands that are 1/3 of an octave apart. This is a standardized form that was specified by ISO (International Standards Organisation).