Board Foot Calculator - Lumber BF, Project List & Cost

How to use it

1. Add one row per distinct board in your cut list. Give it a label if it helps you read the tally back, like shelf sides or table top.
2. Set the quantity, then pick the thickness. Hardwood uses quarters of an inch of rough thickness: 4/4 is 1 in, 5/4 is 1.25 in, 8/4 is 2 in, up to 16/4 at 4 in. Dimensional softwood uses the nominal pair instead, so pick 2x4 or 2x6 and the width fills itself.
3. Enter the width in inches and the length, switching the row to inches if your cut list is in inches rather than feet.
4. Pick a species. That fills a planning price per board foot on every row you have not priced by hand, and sets the density used for the weight estimate. Every price stays editable, per row.
5. Set the waste allowance. The default is 20 percent, which is the middle of the 15 to 30 percent range most shops buy over a hardwood cut list to cover defect cutout, grain matching, and milling loss.
6. Read the slip: total board feet, the waste, the purchase figure rounded up to whole board feet, the cost at your prices, and the estimated weight of the load.
7. Check the board diagram beside the list. It draws the row you are editing with its thickness, width, and length labelled, so a typo in the width shows up as a plank that looks wrong.
8. Buying sawlogs instead of boards? Open the log scale card and enter the small end diameter inside the bark, the log length, and the count. It shows Doyle, Scribner Decimal C, and International 1/4 inch side by side, because the three disagree and the one you scale on decides the price.
9. Use the converters for the two questions that come up at the counter: how many board feet a run of linear feet works out to, and how many board feet cover a given square footage at a chosen thickness.
10. Print the dimensional lumber chart at the bottom for the board footage of every stocked size and length, from 1x2 to 6x6.

At a glance

• Red oak bookshelf: 2 sides plus 5 shelves: 2 boards of 4/4 x 8 in x 6 ft at 4.00 BF each is 8 BF, 5 shelves of 4/4 x 8 in x 3 ft at 2.00 BF each is 10 BF, so 18 BF. Add 20 percent and you buy 22 BF, about $110 at $5.00 per BF, and it weighs about 79 lb.
• 12 studs, 2x4x8: Billed on nominal size, 2 x 4 x 8 / 12 = 5.33 BF each, 64 BF for the run. The same studs measure 1.5 by 3.5 in, which is only 3.50 BF each, and that gap is the single most common board foot mistake.
• One 16 in by 16 ft sawlog: 144 BF on Doyle, 170 BF on Scribner Decimal C, about 200 BF on International 1/4 inch. Same log, three answers, and the rule the mill scales on is worth more than the haggling.

How the math works

Every figure on this page comes from a formula you can check on paper. The board foot itself is 144 cubic inches, so board feet are thickness in inches times width in inches times length in feet, divided by 12: BF = T x W x L / 12. If your cut list is in inches, the same volume divided by 144 gives the same answer: BF = T x W x L(in) / 144. A board 1 in by 12 in by 1 ft is exactly 1 BF either way. The dimensions that go into the formula are the BILLED dimensions, not what a tape measure reads. Hardwood is measured and priced on rough, pre-surfacing thickness in quarters of an inch under National Hardwood Lumber Association rules, so 4/4 stock that arrives surfaced at 13/16 in is still sold as 1 in, and stock thinner than an inch is counted as 4/4. Dimensional softwood is billed on the nominal pair under PS 20, the American Softwood Lumber Standard, so a 2x4 bills as 2 by 4 even though it dries and surfaces to 1.5 by 3.5, and a 2x8 measures 1.5 by 7.25. The tool applies the PS 20 deductions itself: under 2 in nominal loses a quarter inch, 2 through 6 loses a half, 8 and up loses three quarters. Each row multiplies its board feet by its quantity and its own price per board foot. The project total is the sum, the waste allowance is a straight percentage on top, and the purchase figure rounds up to the next whole board foot because that is how the ticket is written. The weight estimate uses the actual measured volume rather than the billed volume, so a stud run is weighed as 1.5 by 3.5, and multiplies it by the species density: the USDA Forest Products Laboratory Wood Handbook publishes specific gravity at 12 percent moisture, and density in pounds per cubic foot is that specific gravity times 62.4 times 1.12, which is 44 lb per cubic foot for red oak and 3.67 lb per board foot. The log rules are the published USDA Forest Service formulas: Doyle is ((D - 4) squared x L) / 16, Scribner in formula form is (0.79 D squared - 2D - 4) x L / 16 rounded to the nearest 10 board feet for Decimal C, and International 1/4 inch sums 0.22 D squared - 0.71 D over each 4 ft section with a half inch of taper added per section. D is always the small end diameter inside the bark, in inches, and L is the log length in feet. The converters fall out of the same formula: a run of linear feet is just the length, and square feet of surface convert with the width cancelling out, leaving board feet equal to the square footage times the thickness in inches.

1. 1. Measure a board foot, not a board

   A board foot is volume: 144 cubic inches, or a piece 1 in thick, 12 in wide and 1 ft long. That is why a lumberyard can quote one price for 4/4 poplar and have two boards on the same rack cost $12 and $31. The formula is thickness in inches times width in inches times length in feet, all divided by 12. A 4/4 board 8 in wide and 6 ft long is 1 x 8 x 6 / 12 = 4.00 BF. Divide by 144 instead if you kept the length in inches: 1 x 8 x 72 / 144 = 4.00 BF, the same board.

2. 2. Use the thickness the yard bills, in quarters

   Hardwood thickness is quoted in quarters of an inch of ROUGH thickness, before any surfacing: 4/4 is 1 in, 5/4 is 1.25, 6/4 is 1.5, 8/4 is 2, and it runs to 16/4 at 4 in. Under NHLA rules the yard measures and prices rough stock, so a 4/4 board that has been surfaced on two faces to 13/16 in is still tallied at a full inch, and anything thinner than an inch counts as 4/4 anyway. This is not the yard rounding in its own favour: you are paying for the wood that came off the log, including the shavings the planer took. Pick the quarter preset that matches the label on the rack, not the reading on your caliper.

3. 3. For dimensional lumber, bill nominal and measure actual

   Softwood framing is a different convention with the same formula. A 2x4 is billed as 2 in by 4 in, so a 2x4x8 is 2 x 4 x 8 / 12 = 5.33 BF, and that is the number on the invoice. The stick in your hand measures 1.5 by 3.5 under PS 20, which would only be 3.50 BF. Half-correcting to 2 by 3.5 gives 4.67 BF and is wrong in a third direction. Bill nominal, always. The tool still tracks the actual size, because the weight estimate and the fit-in-the-truck question depend on the real volume rather than the billed one.

4. 4. Total the list, then add the waste you will actually cut off

   Every row is board feet times quantity, and the project total is the sum. Then add an allowance, because your cut list is finished dimensions and the boards are not: you will cut around knots and checks, trim a split end, reject a board whose grain fights the rest of the panel, and lose a sixteenth off each face flattening rough stock. Fifteen percent covers a simple painted piece from surfaced stock. Twenty to thirty covers a figured hardwood project where the grain has to match across a panel, or rough boards you are milling yourself. The tool rounds the purchase figure up to whole board feet, which is how the ticket comes out anyway.

5. 5. Price it per board foot, then weigh the load

   Cost is board feet times dollars per board foot, per row, because a project can pull cheap poplar for the carcass and walnut for the show faces at the same time. The species presets fill planning prices you edit; they are regional figures that move with grade, width, and thickness, never quotes. The weight line is the one most calculators skip and the one that decides your Saturday. Density in pounds per cubic foot is the Wood Handbook specific gravity times 62.4 times 1.12, so red oak is about 44 lb per cubic foot, which is 3.67 lb per board foot. An 18 BF bookshelf is 66 lb and rides home in a hatchback. A 200 BF white oak kitchen is over 780 lb and is a trailer or two trips.

Worked scenarios, start to finish

Real jobs with the numbers carried all the way through, so you can see how the estimate is built and check your own figures against them.

The judgement calls a pro makes

Decisions the tool cannot make for you, and how someone who does this for a living thinks them through.

How much extra to buy for grain matching

The waste allowance is not one number. A painted shop cabinet out of surfaced poplar needs about 10 to 15 percent, because nothing has to match and the stock arrives flat. A stained oak piece where the door stiles should look like they came off the same board needs 20 to 25, because you will reject boards for colour rather than defect. A figured walnut or curly maple top where the pattern has to run across a panel can want 30 to 40, and the honest answer at that point is to buy the boards in person rather than by the board foot. Rough stock adds its own allowance on top: jointing and planing a 4/4 board down to a flat 13/16 costs you nothing in board feet, since you already paid for the full inch, but a board that cups in the shop can cost you a whole piece.

When to buy 5/4 instead of 4/4

The rule of thumb is that you cannot get a flat, finished 1 in out of a 4/4 board. Rough 4/4 arrives at about 1 1/16, and flattening it honestly leaves 13/16 to 7/8. If your design needs a full inch finished, or the boards have any cup or twist, buy 5/4 and accept the 25 percent extra board footage. It is the cheapest insurance in the yard: 5/4 red oak at $6.25 per board foot against 4/4 at $5.00 is a 25 percent premium on a component that is usually a small part of the project, and it removes the risk of finding out at the planer that you are 1/16 short across a whole panel. Table tops, workbench tops, and anything with a machined edge profile are the usual candidates.

Rough stock or surfaced, when you do not own a jointer

Rough lumber is cheaper per board foot and gives you a full inch to work with, but flattening it needs a jointer and a planer, and without them a cupped rough board is scrap. S2S (surfaced two sides) arrives at a known thickness with the faces flat and costs roughly 10 to 20 percent more, which is genuinely good value for a beginner. S4S adds straight edges as well and is the most expensive. The board footage is the same in every case, because the yard bills the rough thickness it started from, so the price per board foot is where the surfacing shows up. Buy S2S until you own the machines, and remember the board is thinner than the tally says.

Board feet or piece count for dimensional lumber

Studs, joists, and framing are almost always sold by the piece at a retail yard: a 2x4x8 has a shelf price, not a board foot price. Board feet still matter in two situations. Supply houses quote larger orders per thousand board feet (MBF), so a takeoff has to be converted before it can be compared, and mixed loads of different sizes are easier to compare in board feet than in a pile of piece counts. If you are buying twelve studs at Home Depot, count sticks. If you are pricing a framing package against two suppliers, convert to board feet and compare per MBF.

Which log rule to agree before a log leaves the property

International 1/4 inch is the most accurate of the three: it was derived from actual sawing losses and it tracks real yield closely across the diameter range. Doyle is the most widely used in the eastern hardwood trade and the most conservative, badly so under about 28 in, where it can scale a log at half its real yield. Scribner sits between them and is the standard on much federal timber. None of that makes Doyle dishonest, because a mill scaling on Doyle prices per board foot accordingly, and a mill scaling on International pays less per board foot for the same log. The mistake is comparing two offers on different rules without converting them, which is exactly what the three-rule comparison in the log card is for.

Common mistakes, and the fix

• × Using the actual measured size of dimensional lumber instead of the nominal size.

  ✓ A 2x4x8 is 5.33 board feet, billed on 2 by 4. Measuring the stick at 1.5 by 3.5 gives 3.50 BF, which is 34 percent under the invoice, and half-correcting to 2 by 3.5 gives 4.67 BF, which is wrong in a subtler way. Bill nominal for dimensional softwood, always. The actual size still matters for weight and for whether the load fits, and the tool tracks both.

• × Confusing board feet with linear feet or square feet.

  ✓ They measure three different things. Linear feet is length alone, which is what you buy trim and moulding by. Square feet is surface area, which is what you buy flooring and sheet goods by. Board feet is volume, which is what you buy hardwood by, and it is the only one of the three that changes when the thickness changes. Ten linear feet of 1x6 is 5 board feet; the same run in 8/4 stock is 10 board feet. Use the converters in the tool rather than assuming they are interchangeable.

• × Buying exactly the board feet on the cut list.

  ✓ The cut list is finished parts. The boards you buy have knots, checks, split ends, sapwood you do not want, and a crook that has to be jointed out. Every shop buys over: 15 percent for simple work in surfaced stock, 20 to 30 for hardwood you are milling yourself or matching grain across. Coming up one board short in the middle of a glue-up costs a second trip and a board that no longer matches, which is far more expensive than the extra 15 percent.

• × Expecting a 4/4 board to measure a full inch, or arguing about it at the counter.

  ✓ Hardwood is measured and priced on ROUGH thickness under NHLA rules, before surfacing. A 4/4 board surfaced on two faces commonly arrives at 13/16 in and is still sold as a full inch, and boards thinner than an inch are tallied as 4/4 regardless. You paid for the wood that came off the log, including the shavings. If you need a full inch finished, buy 5/4.

• × Scaling small logs on Doyle without saying so.

  ✓ Doyle subtracts 4 in for slabs before squaring, which is close enough on a 30 in veneer log and brutal on a 12 in one: 64 BF against 107 BF on International 1/4 inch for the same 16 ft log. That is not a bug in Doyle, it is what the rule does, and mills price per board foot to match the rule they scale on. Agree the rule before the logs are loaded, and compare offers on the same rule.

• × Forgetting the milling loss when you buy rough stock.

  ✓ Board feet do not shrink when you plane a board, because you bought the rough thickness. What shrinks is your finished dimension. Rough 4/4 flattens to 13/16 or 7/8, 8/4 flattens to about 1 3/4, and a board that cups in the shop before you get to it can lose more. Design to the finished thickness you will actually reach, not to the nominal one, or buy the next quarter up.

• × Treating the species price presets as quotes.

  ✓ They are regional US planning defaults for common grades, and real prices move with grade, width, thickness, kiln schedule, and how far the truck came. Wide clear walnut can be double the figure here; a mill selling green oak off a farm can be half. Edit the price per row with your actual quote before you trust the dollar total, which is exactly why every price on this page is an input rather than a constant.

Material and unit specifics

The board foot itself

144 cubic inches of wood: one inch thick, twelve inches wide, one foot long. It is a volume, which is why it is the only sensible way to price boards that come in whatever width the log gave. The two working forms are BF = T x W x L(ft) / 12 and BF = T x W x L(in) / 144, and they are the same equation. Board feet are also the unit behind MBF, thousand board feet, which is how mills and supply houses quote bulk lumber. A pickup bed full of 4/4 hardwood is roughly 150 to 250 board feet depending on how it is stacked.

Quarter thickness, 4/4 through 16/4

Hardwood thickness is quoted in quarters of an inch: 4/4 is 1 in, 5/4 is 1.25, 6/4 is 1.5, 8/4 is 2, 10/4 is 2.5, 12/4 is 3, and 16/4 is 4. The number is the ROUGH thickness before surfacing, under National Hardwood Lumber Association rules, and stock thinner than an inch is tallied at 4/4. Read as a fraction it is obvious: 8/4 is eight quarters, which is two inches. Surfaced stock arrives thinner than its label (4/4 S2S is typically 13/16), and that is normal rather than a shortfall.

Nominal versus actual, and PS 20

The American Softwood Lumber Standard, PS 20, sets the actual dry sizes behind the nominal names. Under 2 in nominal loses a quarter inch, so a 1x is 3/4 thick. From 2 through 6 nominal loses a half, so a 2x4 is 1.5 by 3.5 and a 2x6 is 1.5 by 5.5. From 8 nominal up loses three quarters, so a 2x8 is 1.5 by 7.25, a 2x10 is 1.5 by 9.25, a 2x12 is 1.5 by 11.25, and a 4x4 is 3.5 by 3.5. Board footage is billed on the nominal pair regardless, which is the whole reason 2x4x8 = 5.33 BF is the most searched board foot question there is.

Species density and load weight

The USDA Forest Products Laboratory Wood Handbook publishes specific gravity by species at 12 percent moisture. Density in pounds per cubic foot is that figure times 62.4 times 1.12, and a board foot is one twelfth of a cubic foot, so pounds per board foot is the density over 12. Poplar at 0.42 specific gravity is 29 lb per cubic foot, 2.45 per BF. Red oak and hard maple at 0.63 are 44 and 3.67. White oak at 0.68 is 47.5 and 3.96. Hickory at 0.72 is 50 and 4.20. Black walnut at 0.55 is 38 and 3.20. Green or freshly sawn lumber is far heavier, often 50 percent more, so treat these as kiln-dried figures.

Rough, S2S and S4S

Rough lumber comes as it left the saw, full thickness and cheapest per board foot, and it needs a jointer and planer to be usable. S2S is surfaced on two faces to a known thickness with flat faces, typically 10 to 20 percent more per board foot, and it is what most hobbyists should buy. S4S adds two straight, square edges and costs the most. In all three cases the board footage is billed on the rough thickness the yard started from, so surfacing shows up in the price per board foot and in the finished thickness, never in the tally.

Log rules: Doyle, Scribner Decimal C, International 1/4 inch

Three published USDA Forest Service conventions for estimating the lumber in a standing sawlog, all taking the small end diameter inside the bark. Doyle, ((D - 4) squared x L) / 16, subtracts a fixed 4 in slab allowance and underestimates logs under about 28 in badly. Scribner was drawn from diagrams rather than derived, and Decimal C expresses it to the nearest 10 board feet. International 1/4 inch sums 0.22 D squared minus 0.71 D over each 4 ft section with a half inch of taper per section, allows a 1/4 in kerf, and is the most accurate of the three. For a 16 in by 16 ft log they give 144, 170 and about 200 board feet respectively.

Buying by the piece, the board foot, or the MBF

Retail yards sell dimensional softwood by the piece, hardwood dealers sell by the board foot, and mills and supply houses quote per thousand board feet (MBF). To convert, divide board feet by 1000: 64 BF at a $600 MBF price is 0.064 x 600 = $38.40. A hardwood dealer will usually also charge a surcharge for wide boards, long lengths, or select grades, so the headline price per board foot is a starting point on a mixed order rather than the whole invoice.

Reading your result

The board foot total is the number to say out loud at the counter, because it is the unit the ticket is written in. The purchase figure below it is what you should actually buy: your cut list plus the waste allowance, rounded up to whole board feet, because dealers tally each board up to the nearest quarter or full board foot anyway and your receipt will almost always read a little higher than a perfect tape measure. That is the most common surprise on a hardwood invoice and it is not an error: rough boards get measured at their widest point, thickness is billed rough, and every board rounds up. Read the cost line as a materials floor at prices you set, never a quote, and expect surcharges on wide, long, or select stock. The weight line is the one to check before you leave: it uses the actual measured volume, so a stud run weighs what it weighs rather than what it bills, and it tells you whether this is a car trip, a pickup, or a trailer. As a reference point, a half-ton pickup's payload is typically about 1,500 lb, which is roughly 400 board feet of red oak or 600 of poplar. In log mode, read the three rules as three different contracts rather than three attempts at one answer: the number that matters is the one in the rule the mill scales on, and the comparison is there so you know what you are giving up when you agree to it.

Limitations

• This is a planning estimate, not a quote. Species prices are editable regional US defaults for common grades and they move with grade, width, thickness, and freight. Always price against your actual dealer.
• The tally uses billed dimensions: rough thickness for hardwood under NHLA rules and nominal size for dimensional softwood under PS 20. A dealer measuring individual rough boards can and usually will come out slightly higher, because each board is measured at its widest point and rounded up.
• The waste allowance is a percentage, not a cutting optimizer. It cannot tell you whether your parts actually nest into the boards on the rack, and a cut list of long or wide parts can need far more than the percentage suggests.
• Weight estimates assume kiln-dried lumber at about 12 percent moisture. Green, freshly sawn, or pressure-treated wood is much heavier, commonly 50 percent or more, and surfaced boards weigh less than their billed board footage implies.
• Log rules estimate yield from a straight, sound log at the small end diameter inside the bark. Sweep, rot, knots, and metal all come off the scale at the mill, and Scribner here uses the published formula form rather than the printed Decimal C table, so a mill scaling from the table can differ by a few board feet.
• This page is geometry and unit math only. It carries no structural, span, load, or building code figures, and it does not tell you what size or grade of lumber a structure needs. That is an engineer's or a building official's call.

Frequently asked questions

How many board feet is a 2x4x8?

5.33 board feet. Board footage for dimensional lumber uses the NOMINAL size, so it is 2 x 4 x 8 / 12 = 5.333. The stud actually measures 1.5 by 3.5 in under PS 20, which would only be 3.50 board feet, but that is not how it is billed. A 2x4x10 is 6.67 BF, a 2x4x12 is 8.00 BF, a 2x6x8 is 8.00 BF, and a 4x4x8 is 10.67 BF. The printable chart on this page has every stocked size at every stocked length.

Is a board foot the same as a linear foot?

No. A linear foot is length only, so a 10 ft board is 10 linear feet whatever its size. A board foot is volume, 144 cubic inches, so it changes when the thickness or the width changes. Ten linear feet of 1x6 is 1 x 6 x 10 / 12 = 5 board feet, but ten linear feet of 8/4 by 6 in is 2 x 6 x 10 / 12 = 10 board feet, twice as much wood for the same run. Trim and moulding are sold by the linear foot, hardwood by the board foot, and flooring by the square foot, which is a third unit again.

Why did the yard charge me for 1 in thickness when my board measures 13/16?

Because hardwood is measured and priced on ROUGH thickness, before surfacing, under National Hardwood Lumber Association rules. A 4/4 board leaves the saw at about 1 1/16 in and arrives at 13/16 or 7/8 after being surfaced on two faces, and it is sold as a full inch the whole way. You are paying for the wood that came off the log, planer shavings included. The same rule says anything thinner than an inch still tallies at 4/4. If you need a full inch of finished thickness, buy 5/4 and plane it down.

How much extra lumber should I buy over my cut list?

Fifteen to thirty percent for hardwood, and the tool defaults to 20. Fifteen covers simple work in surfaced stock where nothing has to match. Twenty to twenty five covers a stained project where you will reject boards for colour as well as for defects. Thirty or more covers figured stock, grain matched panels, or rough boards you are milling yourself and losing a sixteenth a face to. Dimensional framing needs less, usually 10 percent, because the stock is uniform and defects are tolerable. Running short mid project costs a second trip and a board that no longer matches, so the allowance is cheap.

How much does a board foot of lumber weigh?

It depends on the species and it is worth knowing before you load the car. A board foot is one twelfth of a cubic foot, so the weight is the species density over 12. Kiln-dried poplar is about 2.45 lb per board foot, cherry 2.91, black walnut 3.20, ash 3.49, red oak and hard maple 3.67, white oak 3.96, and hickory 4.20. So 100 board feet of red oak is about 367 lb and the same in poplar is 245 lb. Green or freshly sawn lumber can be 50 percent heavier again. The tool computes the load weight for your list from the species you pick.

Which log rule should I use, Doyle, Scribner or International?

International 1/4 inch is the most accurate, because it was derived from real sawing losses and it tracks actual yield across the whole diameter range. Doyle is the most common in the eastern hardwood trade and the most conservative, deducting 4 in for slabs before it squares, which underestimates logs under about 28 in badly: a 16 ft log with a 16 in small end scales 144 board feet on Doyle against about 200 on International. Scribner Decimal C sits between them at 170 for the same log. Mills price per board foot to match the rule they scale on, so the practical answer is to agree the rule before the logs move and compare every offer on the same one.