How to Buy Lumber for Woodworking: Grades, Sizes and Where to Buy

To buy lumber for woodworking, decide the species and finished thickness first, convert your cut list into board feet, add extra for the grade you choose, and check the moisture content before you pay. This guide walks through each step, explains what the hardwood grades actually promise under National Hardwood Lumber Association (NHLA) rules, and includes a worst-case table showing how many board feet to order so you do not run short.

What to Check Before You Buy Lumber

Most buying mistakes come from one of five things: wrong thickness, wrong grade for the job, not enough quantity, wood that is too wet, or a source that does not match the project. The rest of this guide takes them in order. If you only remember one rule, it is this: the size and grade on the tag describe the board as it was sawn or graded, not the piece that will end up in your project.

• Write a cut list with finished sizes, then add a rough-milling allowance for every part.
• Convert the list to board feet and add extra for the grade you plan to buy (table below).
• Decide whether to buy rough or surfaced (S4S) stock.
• Look at both faces of the board, the ends and the edges before you buy.
• Check moisture content, and let the wood acclimate in your shop before cutting.

Hardwood vs. Softwood: What Each Aisle Sells

Softwood dimension lumber, such as pine, spruce and fir 2x4s and 1x boards, is sold with nominal names that do not match real sizes. According to the Wikipedia lumber article, a 2×4 measures 1 1/2 by 3 1/2 inches after drying and planing, and since 1961 the dressed size of a 1-inch nominal board has been 3/4 inch. Hardwood, in contrast, is sold to the consumer by the board foot, which the same article defines as 144 cubic inches.

That difference changes how you shop. For a workbench, shop cabinets or a rough project, construction softwood can work if you pick straight, dry pieces. For furniture, hardwood boards from a lumberyard or sawmill give you more choice of species and grain, but you have to do more of the math yourself.

How Lumber Is Sold: Board Feet and the Quarter System

Hardwood thickness is written in quarters of an inch. Per the Wikipedia lumber article, 4/4 is a 1-inch board and 8/4 is 2 inches, and the number describes rough-sawn thickness before milling. So a board sold as 4/4 will not measure 1 inch after it is surfaced.

The board foot formula is thickness in inches times width in inches times length in feet, divided by 12. Work one example: a 1 inch by 6 inch by 8 foot board is 1 x 6 x 8 / 12 = 4 board feet. A 2 inch by 8 inch by 10 foot board is 2 x 8 x 10 / 12, which is about 13.3 board feet. For a deeper walk through the math, see our guides on what a board foot is and how to calculate board feet. If you are pricing a whole project, how to calculate wood price and how much wood costs cover the budgeting side.

Rough vs. S4S Lumber

Rough lumber is sawn to thickness and width but not planed, so the faces are uneven and the edges are ragged. S4S means surfaced on four sides: both faces and both edges have been milled smooth and square. Our page on what S4S means in lumber goes deeper on the abbreviation, and how to buy rough-cut lumber covers the rough route.

Factor	Rough lumber	S4S lumber
Surface	Sawn, uneven, ready to be milled	Planed smooth on four sides
Tools you need	Jointer and planer, or a shop that mills for you	Ready to cut, though still check flatness
Thickness	Matches the quarter size (4/4 is 1 inch)	Less than the quarter size after milling
Grain visibility	You mostly see color and defects, not the figure	Grain and defects are easy to read
Best for	Buyers who own milling tools and want species choice	Beginners and small projects

A beginner-friendly compromise is to buy rough lumber and pay the yard to surface it, or to buy S2S (two faces planed) stock and joint the edges yourself. Either way, buy thick enough to lose material. If your finished part must be 3/4 inch thick, order 4/4 rough, not 3/4 surfaced.

Hardwood Grades Explained: FAS, Select and No. 1 Common

NHLA hardwood grades are based on how much clear wood you can cut from a board, not on how pretty it looks. The American Hardwood Export Council summary of NHLA grades lists the following definitions for the grades most woodworkers meet at a lumberyard.

Grade	Minimum board size	Clear cutting yield	Smallest clear cuttings
FAS	6 in wide, 8 ft long	83 1/3% to 100%	3 in x 7 ft or 4 in x 5 ft
Select	4 in wide, 6 ft long	Same as FAS One Face (better face meets FAS)	Same cutting sizes as FAS
No. 1 Common	3 in wide, 4 ft long	66 2/3% up to, not including, 83 1/3%	3 in x 3 ft or 4 in x 2 ft
No. 2A Common	3 in wide, 4 ft long	50% up to, not including, 66 2/3%	3 in x 2 ft

Two details are easy to miss. First, FAS requires both faces to meet the minimum, while FAS One Face requires only the better face to meet FAS and the poorer face to meet No. 1 Common. Second, No. 2A Common is judged on the poorest face, so the better face does not change the grade.

How Many Board Feet Should You Buy? A Worst-Case Yield Table

A flat waste percentage ignores the grade. NHLA grades state a minimum share of clear wood, so you can calculate the worst case yourself. Divide the clear board feet you need by the grade’s minimum yield. The result is what you would have to buy if every board sat at the bottom of its grade range.

Grade	Minimum clear yield	Buy this to get 10 clear bf	Buy this to get 20 clear bf	Buy this to get 40 clear bf
FAS	83 1/3%	12.0 bf	24.0 bf	48.0 bf
No. 1 Common	66 2/3%	15.0 bf	30.0 bf	60.0 bf
No. 2A Common	50%	20.0 bf	40.0 bf	80.0 bf

These figures are our own arithmetic from the NHLA minimums above, not a promise from any seller. Real boards often yield more than the minimum, and milling to final thickness, saw kerf and trimming to length take more wood on top of this. The takeaway is that a lower grade is only cheaper if its price per board foot drops by more than the yield does. Dividing the minimum yields, 66 2/3 by 83 1/3 is 0.8, so if No. 1 Common is priced above 80 percent of the FAS price per board foot, it costs more per clear board foot at worst-case yields.

A quick test: for a tabletop or wide door panel that needs long clear pieces, FAS or Select is usually the safer choice. For rails, stiles and small drawer parts that can be cut from short clear sections, No. 1 Common can make sense because the smallest allowed clear cuttings are 3 in x 3 ft or 4 in x 2 ft.

Moisture Content: The Number That Decides Whether Wood Stays Flat

Lumber that is too wet shrinks after you build with it, which can open joints and cup panels. The USDA Forest Products Laboratory Wood Handbook says hardwood lumber for furniture, flooring, cabinets and millwork is usually dried to 6 to 8 percent moisture content, while kiln-dried softwood dimension lumber generally averages 19 percent or less. The same source recommends drying wood close to the level it will reach in service, and it treats 30 percent as the approximate fiber saturation point, the level below which wood starts to shrink.

This corrects a common assumption: kiln-dried does not automatically mean ready for furniture. A 2×4 stamped kiln-dried may be near 19 percent, which can be fine for framing and is too wet for a dining table. Ask the seller how the wood was dried and how it has been stored, and check it yourself.

• Test several boards, not just one, and test away from the very end, which dries fastest.
• Compare the reading with the 6 to 8 percent range for furniture-grade hardwood.
• Bring new boards into your shop and let them sit, stickered, for a week or more before milling, then re-check.
• Do not plane or joint very wet stock and expect it to stay flat; see can you plane wet wood for what happens.

Where to Buy Lumber: Lumberyard, Big Box Store or Sawmill

We did not check individual stores or prices for this update, so the comparison below describes typical differences and what to ask, not what any store stocks this week. Call ahead, because stock, sizes and minimums vary by location.

Source	What it is usually good for	What to ask or watch
Hardwood lumberyard	Wide species choice, graded boards, often rough or surfaced to order	Ask for grade, thickness in quarters, whether it is kiln dried, and if they will mill it for you
Big box home center	Construction softwood and some pre-surfaced boards for small projects	Sort through the stack and check for cupping, twist and moisture
Local sawmill	Unusual species and thick or wide slabs, sometimes air-dried	Ask how long it has dried and whether it has been kiln dried, then test it with a meter
Online lumber dealer	Species you cannot find locally, sold in bundles or by the board	Confirm the grade, dimensions and moisture in writing, and check return terms

How to Inspect Boards Before You Pay

Sight down each board like a rifle barrel to spot bow, crook, twist and cup. Look at the end grain for checks and cracks, and at both faces for knots, wane (bark on the edge) and stain. Check the length and width with a tape, and see whether the tag grade agrees with what you can see. If a yard lets you pick through the stack, take the extra minutes.

Common Lumber-Buying Mistakes

• Ordering the finished thickness. Buy thick enough to mill, as explained above.
• Assuming the tag grade is enough. Grade tells you about clear cuttings, not straightness or moisture.
• Using one flat waste percentage. Use the yield table above for your grade.
• Skipping acclimation. Lumber moved from a damp shed to a dry shop keeps changing.
• Buying in several trips. Color and grain can differ between batches, so buy enough for the whole project together.

Frequently Asked Questions

How do you calculate board feet?

Multiply thickness in inches by width in inches by length in feet, then divide by 12. A rough 4/4 board (1 inch) that is 6 inches wide and 8 feet long is 1 x 6 x 8 / 12 = 4 board feet. Hardwood is sold by the board foot, which is 144 cubic inches.

What does 4/4 mean when buying lumber?

It is the quarter system for hardwood thickness, where 4/4 is a rough board 1 inch thick and 8/4 is 2 inches thick. The number describes the board before it is planed, so surfaced 4/4 stock is thinner than 1 inch.

What is the difference between FAS and No. 1 Common?

Under NHLA rules FAS boards are at least 6 inches wide and 8 feet long and yield 83 1/3 percent to 100 percent clear cuttings. No. 1 Common boards can be as small as 3 inches wide and 4 feet long and yield 66 2/3 percent up to, but not including, 83 1/3 percent.

What moisture content should lumber be for woodworking?

The USDA Forest Products Laboratory says hardwood lumber for furniture, cabinetry and millwork is usually dried to 6 to 8 percent moisture content. Kiln-dried softwood dimension lumber is generally 19 percent or less, which is too wet for fine furniture.

Is it cheaper to buy rough lumber or S4S?

Rough lumber is usually the lower price per board foot because someone else has not yet milled it, but you need a jointer and planer to flatten it and you lose thickness in milling. Prices change by region and supplier, so compare current quotes rather than relying on a fixed figure.

Conclusion

Buying lumber goes well when you work backward from the finished part: choose the thickness in quarters, calculate board feet, add extra based on grade using the table above, and confirm moisture content with a meter before you pay. Prices vary by region and season, so get quotes from a couple of sources rather than trusting any one number.