1 bundle .33 or 1/3 square
3 bundles per sq.
1 bundle for 1 sheet of 4'x8' sheet of CDX or O.S.B
1 roll of felt for 4 sq of roof(unless you have a 4.33 roll)
3 sheets of 4'x8' CDX or O.S.B per square.
When 3 tabs were the usual 1 coil of nails would install 1 bundle of 3 tabs.
Designer shingles have more bundles per square and lifetimes do as well.
3-tabs (20-25) and Limited Lifetimes (30) have 3 per square.