Size is treated as a budget lever. It is really a legibility spec, and the two pull in opposite directions.

One inch: conversation distance

Room for one word in a strong weight, and very little else.

Genuinely right for role buttons — VOLUNTEER, GREETER — and wrong for a name and an office.

Two and a quarter: across a room

The default for a reason. A name, a short line and a mark all read comfortably.

This is the size most campaigns should be ordering and the size most under-order.

Three inch: across a hall

A name, an office and a strapline without any of it dropping below readable.

Worth the extra cost the moment the room is bigger than an office.

Six inch: down a rally line

Reads at distance and survives being cropped into a photograph.

Needs a reinforced or locking pin, or it tips forward on soft fabric.

The honest test

Stand where the furthest person will stand and ask whether a name would read from there.

If it would not, the cheaper button has cost you the whole order.