How to understand lumber measurements?

Question

...This is probably a dumb question, but I'm trying to figure out what size boards I need for a project I'm doing, and I'm looking at some lumber online and I don't understand what measurements like 1x2x6 mean....is that in inches? feet? Is that width, length, or what?

So....what do measurements like 1x2x6 mean?

....o_o........Why on earth is it actually 1 1/2 inches if it's labeled as being 2 inches? And....is there some kind of formula for figuring out what the actual measurements are as opposed to the stated measurments without actually measuring the board in person?

Answer 1

The first two numbers are the cross-sectional dimensions in inches, whereas the last number is the length in feet, which is usually an even number between 6 and 20.

The cross-sectional dimensions are the "rough" measurements as it comes from the saw at the lumber mill, before it is run through a planer to make it smooth. Finished lumber is given the designation "S4S", which means surfaced four sides. Normally, the planer takes 1/4" off each side, except for 1" thick material where only 1/8" is taken off each side. Thus, S4S finished lumber is actually 1/2" less than any given dimension of 2" or more. Some common lumber sizes are:

1x2: 3/4" x 1 1/2"
2x4: 1 1/2" x 3 1/2"
2x12: 1 1/2" x 11 1/2"
4x4: 3 1/2" x 3 1/2"

Most larger lumberyards also carry rough lumber, which hasn't been planed, for applications where appearance is not an issue. Rough lumber is slightly cheaper, and has a slightly higher strength resulting from the extra material.

Answer 2

Lumber Measurements

Answer 3

1

Answer 4

yeh i know your frustration big time. its not a dumb question. lumber yards should realize tht alot of people do not know this language and they should dispay the proper ticks after the numbers or use words. 1x2x6 could mean two different things first of all you need to know if you are dealing with dressed or rough lumber. if it is rough that is what you basically get a piece of wood that is 1 inch thick 2 inches wide and 6 feet long. if it is dressed then you get a piece of wood that is closer to 11/16 thick and 1 and 1/2 wide and 6 feet long. if you can take note of this remember thickness width length and in that order (TxWxL). The lumber dimensions for s4s ((surfaced 4 sides) (dressed)) are
thickness is always about 1/2 an inch under the full marked size. execption 1 inch thick is 11/16, 2 inches thick is 1 and1/2 inches thick. this also aplies for the width if they state it is 4 inches wide then in reality it is only 3 and a 1/2 inches wide. when it comes to the length your safe it they state it is 6 feet long thats waht you get. one other thing that is good to know is always order more then you need 10 PERCENT there is always waste, because of flaws in the wood and one more thing if you have to figuere out the board measure remember this equation length x width will give you your board measure. keep in mind if yu are to measure in inches divide yur toatal by 12 and you will have board feet. 2"=2 inches 2'= 2 feet. the little ticks.
my self buying lumber unseen is not a good idea. he could ship you a pile of crap and lumber is to espensive. it would not be nice if you payed for it then recieved a pile of wane or cups or twists and heartwood, shake,split ,cracks. all this type of lumber is not good if i was you i would check the lumber out in person then you know what your getting. and if yu do not know what defincies you are lookng for in lumber take someone you does know. good luck ide do it for you but for some reason i havent yet figuered out how to transport myself through this computer.

Answer 5

1x2x6 could mean 1" x 2" x 6 ft -- if it is labeled as rough lumber.
Or it could mean 3/4" x 1-1/2" x 6 ft -- it is surfaced on all 4 sides.

Softwoods such as douglas fir, larch, pine, etc for construction framing construction are usually manufactured with all 4 sides having a smooth surface. They are typically labeled S4S for Surfaced 4 Sides.

These boards start out as full-dimensional boards, 2" x 4", 2" x 6", etc with a rough finish cut directly from the logs. They are further processed through either a planer or sander which mills them down in size, removing about 1/4" on each side - or removing 1/2" from the original rough lumber.

The first two numbers refer to the thickness and width, expressed in nominal inches. The third number is the length in feet. For lumber in the shorter dimensions, 6 thru 10 ft, they are generally exactly that length. For longer pieces, the lumber is equal to or slightly longer than the stated length, due the fact that trees don't grow in even 2 ft lengths.

Having said all of that, note that hardwoods used in furniture are usually exact dimensions, and are sometimes measured in quarters, for example 3/4 inch, 4/4 (1 inch), 5/4 (1-1/4 inches), etc. This would be for oak, walnut, cherry, and other hardwoods.

Finally, manufactured or engineered woods (plywood, OSB or Oriented Strand Board, etc.) are also in exact dimensions. A 4 ft x 8 ft sheet of plywood would be labeled 48x96x 3/4 inches. With more attention focused on cost efficiencies, plywood mills are further shaving their panels using 1/16" or even 1/32" increments for the thicknesses of their panels. So instead of 3/8", 1/2" or 3/4" thick plywood, you will find 7/32", 15/32" or 23/32" thicknesses (or perhaps 5/16", 7/16" or 11/16" thicknesses.)

The industry is confusing, probably just because they can get away with it.

Answer 6

As you now know, a 1x2x6 is a misnomer. In the olden days (probably when the world was still flat), a 1 by 2 measured 1" by 2". It was the size of the wood after it had been dried. Dimensional lumber is now cut at 1" by 2" and then dried. It's called the nominal measurement and the wood gives up about 1/4 inch all around after it dries.

Answer 7

The last gal was right in her explanation, but what you need to understand is that the terms came about when lumber actually was that size. Now, a 2 x 4 x 8 is actually 1-1/2" x 3-1/2", (only the length, the third dimension, only holds true anymore). but wait,there's more! If you go to (no offense intended):

http://www.mistupid.com/homeimpr/lumber.htm

They can give you the whole scoop on that. Additionally, the site

http://woodworking.about.com/od/?once=true&

has alot of great information about calculating board feet so you can order the proper amount of lumber.
Good luck on your project.

Answer 8

Lumber mills buy the whole log.
It goes in to their inventory that way.
When you buy cut stock, you also pay for the sawdust left as the lumber is processed for your order.
That way they can account for the whole log.

So you need to know the standard amounts the rough lumber is cut to so as to produce the smooth faces you see in the retail end.

I have milled many board feet of rough, and it almost always comes out to be the exact dimension of usual dressed lumber when the dross is planed out.

So relax. It is not a cheat system, you are just being charged for the sawdust ( and the processing which on mill scales is MUCH cheaper than homeowner input).

Answer 9

1 inch thick x 2 inches wide x 6 feet long.
Also, keep in mind that a finished "1 by 2", "2 by 4", etc. is not actually 1 inch thick by 2 inches wide. The nominal size of lumber is designated before the piece is dried and surfaced, so the finished size is smaller. Here are some examples:
2 by 3 = 11⁄2" by 21⁄2"
2 by 4 = 11⁄2" by 31⁄2"
2 by 6 = 11⁄2" by 51⁄2"
4 by 4 = 31⁄2" by 31⁄2"

Good luck to you!

Answer 10

The reason it says 2" and is actually 1.5" is that the 2" is a nominal measurement taken prior to drying of the lumber. Once the lumber drys it shrinks. It is just accepted as industry standard.