M-Style Bobbin Thread Capacity

[GerryR]

I would like to know the capacity of M-style bobbins for #69, 92, 138 and 207 thread,  I looked up for prewound bobbins for #138 thread and they stated 36 yds. but said  the same for 92 thread, which didn't sound right to me. (They were probably just loading a fixed amount on the bobbins, not filling to capacity.)  I would like to know the full capacity, +/-, of the M bobbins for the size threads stated.  Can anybody help?  Thanks.