Quota is the term used for the smallest number of votes that will guarantee the election of a candidate.

In a first-past-the-post election, where there is one and only one winner, quota is the well-known 50% + 1. Expressed mathematically, it’s (12*v + 1) where v is the total number of votes. A candidate with that many votes can’t be beaten by anyone else; there simply aren’t enough votes left. A candidate could be elected with fewer votes, but (12*v + 1) guarantees a win.

In a region where we elect two winners, quota is (13*v + 1). If candidates A and B both have just over 13 of the votes, no other candidate can obtain more than 13 to beat them.

Similarly, in an election with three winners, quota is (14*v + 1) and for four winners quota is (15*v + 1).

The general formula is $$\frac{1}{n+1} v + 1$$ where n is the number of people to be elected and v is the number of votes.

There are actually several different ways to calculate quota. This approach is known as Droop quota.