Pretty much whatever number you want to make it.

Most state nonprofit corporation laws and the Model Nonprofit Corporation Act allow the drafters of a nonprofit’s governing document to set quorum requirements as they wish, providing default requirements if the governing documents do not specify otherwise.  Like so many other things about a nonprofit, no one size fits all.

The quorum requirements for membership corporations are particularly varied.  The drafters want to be sure the quorum requirement is realistic.  For organizations with large lists of members who are not actively engaged in governance, it may be totally unrealistic to expect that a majority would ever show up for a membership meeting.  It may be more realistic to have a quorum be 10% or 15% of the members.  If the drafters don’t expect the members to take significant corporate actions, it may be appropriate to say a quorum is whatever number of members actually show up for the meeting.  If the membership is five or six founders who want to be sure that they all control the organization, however, a quorum requirement may be four or five of them in order to assure that everyone participates in the governance.  The one thing you don’t want to do is require a 100% quorum.  That would allow a single recalcitrant to wreak havoc with governance by staying away from the meetings.  The key is to think through how the organization is likely to function and to provide a realistic quorum requirement in light of the type of membership and their anticipated involvement.

The quorum requirement for the board of directors is probably less varied, and a requirement for a majority of directors to constitute a quorum is usually a safe provision.  (You don’t want to make it “50% plus one” because it isn’t always clear what that means.  (See: Should quorum be 50% plus one?))  Boards that have a large membership for ceremonial or representational purposes but don’t expect a lot of participation from those honored with a position on the board may want a quorum of less than 50%, but if you are having trouble getting a majority of a smaller working board to participate, you probably want to think about getting some new directors.  If you want to assure general consent for particular actions, like a merger or removal of a director, you can also vary the voting requirement.  Instead of requiring a majority of a quorum to constitute corporate action, you can require a majority (or more) of all directors in office.  Again, the key is thinking through how requirements may play out in real life.