what's the meaning of this ?

[papadoo1]

what do they mean when describing 2/4 or 4/4 when describing finish lumber boards ? I assume it means planed finish, like on

2 sides or 4 sides ? Can someone explain please ?

[George Max]

It's a measure for rough lumber. 2/4 = 1/2" thick, 4/4 = 1" thick and so on.

[Doug Miller]

2/4 or 4/4 refers to nominal rough-sawn thickness in inches. Read as two-quarter or four-quarter. Means half-inch and one-inch respectively.

The number of finished sides is given as S2S, S3S, or S4S, meaning "surfaced 2 sides", "... 3 sides", etc. or sometimes just as S2, S3, or S4.

A 4/4 board is 1 inch thick in the rough, and when surfaced two (or more) sides, will be 13/16" thick (if hardwood) or 3/4" thick (if softwood).