Board Foot Calculator

Board Foot Calculator for hardwood and 2x lumber. Enter rough thickness, width, length and price to see billed board feet, the NHLA tally, S2S planing loss, waste and project cost.

Board Foot Calculator Math for Rough Lumber

One board foot is a piece 12 inches wide, 12 inches long and 1 inch thick, or 144 cubic inches. Hardwood dealers sell random-width boards in that unit because a price per length would charge the same for a 4-inch board and an 8-inch one.

The Board Foot Calculator turns rough thickness, width, length and board count into billed board feet, then prices the order. It helps a hobbyist check a yard's tally, a cabinet shop compare species costs and a small sawyer price 5/4 and 6/4 stock.

The standard formula takes thickness and width in inches and length in feet. Dividing by 12 brings that mixed product back to 144-cubic-inch units.

$$BF=\frac{T\times W\times L}{12}$$

T is rough thickness in inches, W is width in inches and L is length in feet. With the default entries, six 5/4 boards that are 7 inches wide and 10 feet long hold 7.29 board feet each, or 43.75 board feet in total. If you measure length in inches too, the divisor becomes 144.

The hero shows that total and the per-board figure. The cost card prices the order with waste included and shows what the waste alone costs. The order card adds the waste allowance and rounds up to whole boards, so the default 52.50 board feet becomes eight boards of the same size.

Paying for Wood the Planer Removes

Hardwood is sold by rough thickness in quarter inches, so 4/4 means 1 inch and 8/4 means 2 inches. Paragraph 16 of the NHLA Rules for the Measurement & Inspection of Hardwood & Cypress says surfaced lumber is measured before surfacing. A 4/4 board planed to 13/16 inch is still billed as 1 inch thick.

Paragraph 14 of the same rules sets the standard S2S thickness. Stock up to 1-1/2 inches loses 3/16 inch, and stock from 1-3/4 to 4 inches loses 1/4 inch. The American Hardwood Export Council lists the same deductions. The last column shows how much of the wood you paid for leaves as planer chips.

Thin stock loses the biggest share. The table also explains why a finished part a full inch thick has to come from 5/4, since 4/4 surfaces to 13/16. The third result card applies these figures to your entry and shows the board feet left after S2S.

Enter a planed size such as 13/16 or 1-1/16 and the tool flags it as surfaced. It then maps it back to the rough thickness a dealer bills. Two sizes are ambiguous, because 1-1/2 inches is rough 6/4 or planed 7/4, and 1-3/4 inches is rough 7/4 or planed 8/4. To work backward from a finished part to the rough stock to buy, use the Rough to Finished Lumber Calculator.

Stock Thinner Than 4/4

NHLA paragraph 16 counts standard thicknesses under 1 inch as 1 inch. A 3/4 inch board 6 inches wide and 8 feet long holds 3.00 board feet of wood but bills as 4. You pay for a third more wood than you receive.

The tool warns you when rough stock under 1 inch is entered in the measured mode. Switch Measuring Method to Dealer Tally to match a hardwood invoice for 3/8, 1/2, 5/8 or 3/4 inch stock.

Why the Yard's Tally Won't Match Your Tape

Dealers don't multiply exact dimensions. Under NHLA paragraph 16, each board's surface measure is width in inches times length in feet, divided by 12. That figure is rounded to the nearest whole square foot before it is multiplied by thickness.

Extra inches past a whole-foot length are dropped first. A surface measure that lands exactly on the half goes up on one board and down on the next.

$$BF=\mathrm{round}\left(\frac{W\times L}{12}\right)\times T$$

Take an 8/4 board 6-1/2 inches wide and 10 feet 5 inches long. A tape gives 11.28 board feet. The tally drops the length to 10 feet, rounds 5.42 square feet down to 5 and multiplies by 2 for 10 board feet. At $12 a board foot, that rounding saved the buyer about $15.

Set Measuring Method to Dealer Tally, NHLA Rules to get this count, and the hero shows the tape figure beside it. Dry stock can also read thin and still count full. The NHLA Standard Kiln Dried Rule lets rough stock from 3/8 to 1-3/4 inches run 1/16 inch scant, so a dry 4/4 board at 15/16 inch still tallies as 1 inch.

NHLA paragraph 18 tallies random widths in surface measure first and multiplies by thickness afterward. Add Board to List follows the same habit. It keeps a running project list and totals the board feet for each thickness, so a mixed order of 4/4 and 8/4 is grouped the way a dealer stacks it.

2x Lumber Counts at Nominal Size

Softwood follows a different rule. PS 20-25, the American Softwood Lumber Standard, defines board measure with nominal thickness and nominal width. Its Table 3 sets the dry dressed sizes, so a nominal 2x4 is actually 1-1/2 by 3-1/2 inches.

An 8-foot 2x4 counts as 5.33 board feet but holds 3.50 board feet of wood. Nominal counting overstates the wood by about 52 percent on a 2x4 and about 45 percent on a 2x6. The Softwood Nominal (2x4) mode shows both figures and swaps the thickness chart for PS 20 dressed sizes.

The gap matters when you convert to metric volume. PS 20 measures cubic meters on dressed sizes and warns against converting nominal board feet straight to cubic meters. The volume card follows that rule and reports the wood actually in the boards, while its thousand-board-feet row stays on the billed count.

Setting Waste in the Board Foot Calculator

The Extra for Waste field adds a percentage on top of the billed board feet. Many woodworkers on the Fine Woodworking forum plan 20 to 30 percent for rough stock. Some buy 50 percent extra for projects that need close grain and color matching, because boards from a later batch rarely match.

The field works as a markup, which trips up anyone who thinks in yield. A WOODWEB cabinetmaking thread shows the math. If 30 percent of what you buy becomes offcuts and chips, adding 30 percent leaves you short, because you need 142.9 board feet to finish with 100.

$$w=\left(\frac{1}{1-y}-1\right)\times 100$$

Here y is the fraction you expect to lose and w is the percent to enter. A 30 percent loss needs 42.9 percent in the field. These waste figures are shop conventions from working woodworkers, not a published standard, so your own cut lists are the better guide.

A Sawmill Creek member measured one case. A rough 1 × 6 inch board 8 feet long, milled to 3/4 × 5 × 84 inches, kept 2.19 of its 4 board feet. That 45 percent loss calls for about 83 percent in the waste field.

After waste, the order card rounds up to whole boards of the entered size. Buy full lengths where you can, since short offcuts rarely fit the next part. To plan loss from a real cut list, pair this with the Lumber Yield Calculator and the Kerf Spacing Calculator.

Converting MBF and Per-Piece Quotes

Not every seller quotes per board foot. Price Quoted accepts four quote types and turns each into one board-foot rate, so species and suppliers compare directly. A wholesale price of $1,500 per MBF is $1.50 per board foot, since MBF means a thousand board feet.

Linear-foot prices depend on the cross section. A 4/4 board 6 inches wide holds 0.5 board foot per running foot, so $5 per linear foot works out to $10 per board foot. Per-piece prices divide by the board feet in one piece, so a $4 2x4x8 costs $0.75 per nominal board foot and about $1.14 per board foot of actual wood.

Twelve board feet fill one cubic foot, so the $12 default equals $144 per cubic foot of rough lumber. One board foot is also 2.36 liters, which is the factor the volume card uses for cubic meters. Once you know the volume, the Wood Weight Calculator estimates what the load will weigh.

Lumber Yard Tally Puzzles

Why did the yard charge more board feet than I measured?

In one Sawmill Creek thread, six 4/4 cherry boards that measured 35.2 board feet were rung up at 55. Check the thickness first. A 4/4 board billed as 5/4 adds 25 percent before anything else happens.

Next, ask whether the price is net or gross tally. Gross tally is measured before kiln drying, and AHEC says to expect about 7 percent fewer board feet after drying. NHLA's rulebook puts kiln shrinkage at 5 to 9 percent by species.

The same rulebook quotes a 1977 model regulation from the National Conference on Weights and Measures. Lumber measured after kiln drying is to be invoiced on net footage, with no footage added for shrinkage. The Wood Shrinkage Calculator shows how much a board loses as it dries.

What is the difference between a board foot and a linear foot?

A linear foot is length only, while a board foot is volume. Twelve linear feet of 4/4 × 6 inch stock hold 6 board feet, but twelve linear feet of 8/4 × 8 inch stock hold 16. Board feet per linear foot equal thickness times width, divided by 12.

A University of Wisconsin forestry extension sheet works two lumber yard cases. A 10-foot 2x6 holds 10 board feet, and an 8-foot 1x8 holds 5-1/3 board feet, both on nominal size.

Do I round a 5-1/2 or 22-1/2 inch width?

Not on a board rule tally, which is the count a lumber tally stick gives. Width stays as measured and only the surface measure is rounded. A 5-1/2 inch board 8 feet long has 3.67 square feet, which rounds to 4, while a 22-1/2 inch board 8 feet long lands on exactly 15.

Width rounding belongs to the export or 12-foot-basis tally in NHLA paragraph 21. There, widths below the half inch drop and widths above it round up. A width that lands exactly on the half inch goes up on one board and down on the next, so two 5-1/2 inch boards count as one 6 and one 5.

What thickness goes in the formula for 5/4 and 6/4 I sawed myself?

Use the standard thickness, 1.25 for 5/4 and 1.5 for 6/4, not a caliper reading of green wood. NHLA paragraph 9 measures a rough board at its thinnest cutting. A 4/4 or 5/4 board may vary up to 1/4 inch over standard along its length, and 6/4 or 7/4 up to 3/8 inch, before it is called miscut.

A green 5/4 board sawn at 1-3/8 inches still tallies at 1.25 inches. For a stack, total the surface measure for each thickness and multiply once. As an example, 200 square feet of 6/4 is 300 board feet.