Carpentry and Woodworking - How big is a 1x8?

replaced some floorboards recently, and much to my surprise, the width of a 1x8 apparently varies from 7-1/2" to 7' even.

What the heck is that about?
80% of the floor has boards that are 7-1/2" wide.
Some of the older boards are 7-1/4" wide, so I had to make sure every board I re-used went back down just so.

But the boards from the local Box store were down to 7" wide and 7-1/4".
Sure they were low quality with knots and such, but I expected them to at least be the same size.
Is this a product of getting cheap wood, or is this just how things have progressed? (regressed?)

All the kiln dried 1x8's I have ever used where 3/4" in thickness and varied between 7 1/4 -7 1/2" in width. I'm not aware of the lumber dimensions be down sized but I suppose its possible. All wood shrinks as it dries. My front and back porches [covered] are both decked with saw mill 1x6"'s I nailed them as close together as possible but after drying the gap between them is approx 1/2".
There is a cut rate building supply store in a town near me that sells a lot of lumber that appears just like what others sells. I made the mistake of buying some plywood there once. Looked like good sheets but they weren't square.

I have a hundred year old house that by now I am sure that the wood has dried and believe it or not my house hasn't shrunk 1/2 to 3/4 of an inch.

So kiln dried wood is shrunk as compared to what we got all those years ago?
Then why do they call them 1 x 8 if they are 1 x 7 1/4?
:wall:

Lumber width varies depending on the supplier. Most bundles you open will be pretty standard... 1x8's around here seem to be 7 1/4" wide. It depends how the board was cut, milled and sanded... and to a lesser degree how much it shrinks. Usually you only have significant shrinkage in the dimension of treated lumber, but it all depends on the moisture content of the wood when you get it, vs a year later when it dries out.

BigJim, you must be really old if you measured your house 100 years ago and know that it hasn't shrunk. ;) Wood from 100 years ago was much more dense and as a result, shriks less that the soft lumber today. Most lumber usually only shrinks in its width, not its length. In our local lumberyard, anything over 7" wide is considered a 1x8.

1x8 would be that dimension when sawn, before drying and milling. The standard sizes for dimensioned lumber were settled here a decade or more back so that you wind up with 1x8 that is 7.25 inches wide. There was a time when it would have been 7.5 inches, but no longer. Far enough back in time, you would find dimension lumber that was the actual size. My house has 2x4 and such that are actually 2x4, 2x6, and so forth after milling.