From the "scale" indicated by the picture I'd guess they're using 5/8 or 3/4" buttons. And I remember reading that horizontal buttonholes are much better than vertical ones, for not "popping".
The picture shows five buttons but depending on what's comfortable for you (or if you have another favorite cardigan to reference) you might want six or even seven.
no subject
From the "scale" indicated by the picture I'd guess they're using 5/8 or 3/4" buttons. And I remember reading that horizontal buttonholes are much better than vertical ones, for not "popping".
The picture shows five buttons but depending on what's comfortable for you (or if you have another favorite cardigan to reference) you might want six or even seven.
Hope that helps...