Board foot calculator
Enter the finished size of your parts. This works back to the rough lumber you have to buy to get them.
= 0.75"
Straight off the mill. You pay for the saw marks, the cup and the wane, and you mill it all away.
Advanced settings$14 a board foot · ballpark
Ballpark — use your yard's price
Buy this much
7.80board feet
Estimated cost
$109.20
Approx. weight
25 lb
Finished volume
4.50 bf
Your parts contain 4.50 bf of wood. Milling 3/4" parts needs 1" rough stock, which takes that to 6.00 bf, and the Rough allowance of 30% for cutoffs and defect brings it to 7.80 bf.
Ask for
1 4/4 walnut, 12 ft long and about 8″ wide
8.00 bf — 3% over what you need, and each board yields 4 of your pieces. Hardwood is sold random-width, so expect the yard to hand you something close rather than exact.
Working black walnut
Machines beautifully and finishes with almost no effort — the colour is already there, so oil is usually enough. It is soft for a hardwood, so it dents. Sapwood is near-white and most yards sell walnut steamed, which drags that colour toward the heartwood; if you want the contrast, ask for unsteamed and expect to pay for it.
38 lb/ft³ · Janka 1010 lbf · prices reviewed 2026-09-01
Where to buy this
- 7.80 board feet of WalnutHome DepotLowe's
Big-box stores carry a handful of species in nominal sizes; for anything else a hardwood dealer sells by the board foot, which is what this figure is in.
Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.
Worked example: four walnut parts
Four walnut parts, each 36" × 6" × 3/4" finished, are 4.50 board feet of finished wood.
Bought rough, the thickness goes up to 1" stock and a 30% allowance covers milling and defects, so the order is 7.80 board feet: about $109.20 at $14.00 a board foot (a ballpark price, reviewed 2026-09-01).
At the yard that is one board of 4/4 stock, 12 ft long and about 8″ wide.
- Finished board feet
- 4.50
- Board feet to buy
- 7.80
- Rough thickness
- 1"
- Estimated cost
- $109.20
- Approx. weight
- 25 lb
These are the figures the calculator above opens on. Change any field and it works the same problem for your numbers.
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About buying lumber
- How do you calculate board feet?
- Multiply length in inches by width in inches by thickness in inches, then divide by 144. A board foot is 144 cubic inches — nominally a piece 12" × 12" × 1". Lumber is priced this way because it measures volume, so a wide thin board and a narrow thick one cost the same if they contain the same wood.
- Why is the board footage higher than my finished dimensions?
- Two reasons. First, thickness: a finished 3/4" part has to be milled out of 4/4 rough stock, which is a full inch, so you buy an inch and plane a quarter of it into shavings. Second, defect and cutoff waste: Rough adds 30%, S2S adds 20%, S4S adds 10%. Both are applied here, and both numbers are shown so you can see where the difference came from.
- What do 4/4 and 8/4 mean?
- Quarters of an inch of rough thickness. 4/4 is "four quarter", nominally 1" off the saw, dressing to about 13/16". 8/4 is 2" rough. Hardwood is sold this way because the rough thickness is what the mill cut, and what it dresses to depends on how straight it dried.
- Are these prices accurate for my lumberyard?
- No. They are ballpark national averages for reasonable-grade stock, last reviewed 2026-09-01, and hardwood prices vary enormously by region, grade, width and who you buy from. Use them for a first estimate, then type in your yard's actual price — the field is editable for exactly that reason.
- Does this include an allowance for mistakes?
- Only the standard waste factor for the material state you pick. If you are new to a species, cutting a lot of small parts, or working around figure and defect, buy more than this says. Nobody has ever regretted the extra board foot.
By species
Same calculator, with the price and density already filled in.
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