Buttons get compared on diameter and unit price, because those are the only two numbers most suppliers publish. Neither of the first two questions below is about either of them.

How much of the face can I actually use?

A button prints flat and finishes domed, so the artwork wraps over the curve and tucks under the crimped rim.

Ask for the live area as its own number. On a 2.25 in shell it is roughly a quarter inch smaller in diameter than the print.

How far does it have to read?

One inch is conversation distance. 2.25 in crosses a room. Three inch crosses a hall.

Six inch reads down a rally line and photographs well, which is a different job again.

What is on the back?

A safety pin puts a hole in fabric, which decides whether knitwear and suiting audiences ever wear it.

A magnet pierces nothing. A locking pin stays square. A clip suits lanyards.

Does the disclaimer have to fit?

Small items on which a disclaimer cannot conveniently be printed are generally exempt under federal rules, and buttons are named among them.

State rules differ and your counsel decides. Ask before you shrink a name to fit it.

Then choose the colour

Enjoyable, and safely secondary to the four above.