Wis. Stat. § 185.14: Quorum.

(1) A quorum at a member meeting shall be 10 percent of the first 100 members plus 5 percent of additional members.

(2) Unless the bylaws fix a larger number of members to constitute a quorum and except as provided in the bylaws in accordance with s. 185.12 (4) (b) 2., a quorum shall never be more than 50 members nor less than 5 members or a majority of all members, whichever is smaller. Members represented by signed ballots may be counted in computing a quorum only on those motions for which the signed ballots were submitted.