How many people should be in a meeting?

The arithmetic nobody does

In a thirty-minute meeting with four people, each person has seven and a half minutes of airtime if it is shared evenly. With twelve people it is two and a half minutes each — less than it takes most people to make one substantive point.

Nobody actually splits time evenly, which is the real issue: the airtime does not spread thin, it concentrates. Two or three people talk and the rest attend. Everyone else's time is spent, and the organisation pays for all of it.

Size by purpose, not by politics

A meeting that decides something works best at two to five people. Past five, agreement stops being reached and starts being brokered afterwards, which means the meeting did not decide anything.

A meeting that works through a problem tolerates five to eight. You want enough perspectives that someone spots what you missed, and few enough that a disagreement can be followed to its end.

A meeting that informs can be any size at all, because participation is not the point — but if participation is not the point, ask whether it needed to be a meeting rather than a written update people can read at their own pace.

Why the list grows anyway

Invite lists inflate for social reasons, not practical ones. Leaving someone out reads as a judgement about their importance, so it is safer to add them. Nobody is ever criticised for inviting one person too many; people are criticised for leaving someone out.

The fix is to make exclusion explicitly not a slight. 'Small working session, I will send notes' costs one sentence and removes the entire problem. Most people are relieved.

The scheduling cost people forget

Every person added to a meeting makes it harder to schedule, and not linearly. Four busy calendars usually have a common slot within a week. Ten rarely do, so the meeting either lands three weeks out or displaces something already booked.

That delay is a real cost and it is invisible, because it shows up as 'the earliest we could all do' rather than as a consequence of the invite list. If a meeting cannot be scheduled inside a week, the honest reading is usually that it has too many people in it.

How to cut a list you have already written

Go through it once and mark each name as decides, contributes, or needs to know. Everyone in the third group comes off and gets the notes instead — that is usually a third to a half of the list.

Then check the second group for people who are there to represent a function rather than to say something specific. One person can usually carry a function; two rarely add to it.

If cutting feels risky, invite the borderline people as optional and mean it. Optional that is understood as mandatory is worse than no distinction at all.