Lumber and Board Feet Calculator

Board feet from real dimensions, weight and cords kept honest

Enter each board by its actual thickness and width in inches and its length in feet, and this calculator returns board feet, the trade’s volume unit, plus total cubic feet, an estimated weight from a species density you choose, and the cost at your price per board foot. A preset list converts the common nominal sizes (the famous 2×4 is not 2 by 4) to their real dimensions so the famous lie never enters the maths. A second small tool below handles firewood: stacked volume in, cords and estimated solid wood out, with the air in the stack admitted rather than hidden.

Boards (actual dimensions)
Firewood: stacked volume to cords

Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. Densities and cord yields are typical published values that vary with species, moisture and stacking; weighbridge and supplier figures govern real transactions.

What this calculator does

A board foot is 144 cubic inches of wood: a board an inch thick, a foot wide and a foot long. Lumber is priced by it because it prices volume rather than pieces, so a wide board and a narrow one stop pretending to be the same purchase. The calculator’s one act of honesty enforcement is the dimensions: board feet computed from nominal sizes overstate every board, since the 2×4 on the rack measures 1.5 by 3.5 inches after drying and planing. Presets for the common sizes fill in the real numbers, and custom entries take whatever your calipers say, because rough-sawn and resawn stock answer to no standard table.

How to use it

  • Measure, or use the preset. Yard lumber conforms to the standard actual sizes in the preset list; anything from a sawmill, a resaw or a salvage pile gets measured at its thickest and widest, since you pay for the whole board.
  • Length is in feet, the other two in inches. The board foot formula mixes units on purpose (it is three centuries of habit), and the field labels repeat the units so the mixture is a choice, not a trap.
  • Density is the weight’s whole story. The preset densities are typical dried-wood values; green wood can weigh half again as much, which is why the weight is labelled an estimate and the species is yours to set.
  • Cords are stacked measure. A cord is 128 cubic feet of stack, air included. The solid-wood figure the tool reports uses the standard mid-range yield and the content below explains why honest sellers and buyers both tolerate the range.

The formulas

  • Board feet per board = (thickness in × width in × length ft) / 12. Totals multiply by quantity and sum across rows.
  • Cubic feet = board feet / 12. Weight = cubic feet × density. Cost = board feet × price per board foot.
  • Nominal to actual (softwood yard standard): 1× boards are 0.75 in thick, 2× are 1.5 in; widths run a half inch under nominal up to 6 in and three quarters under above (a 2×8 is 7.25 in wide), with 4×4 posts at 3.5 × 3.5.
  • Cords = stacked cubic feet / 128. Estimated solid wood ≈ 85 cu ft per cord, the mid-range of the commonly published 80 to 90 cu ft, because bark, gaps and log shape decide the rest.

Worked examples

The classic 2×4. At its real 1.5 × 3.5 in over 8 ft: (1.5 × 3.5 × 8) / 12 = 3.50 board feet per board, so ten boards are 35.00 board feet and 2.92 cu ft of wood. In kiln-dried pine at 31 lb per cu ft the pile weighs about 90.42 lb, a number worth knowing before the roof rack or the small trailer gets a vote. Computed at the nominal 2 × 4 instead, the same boards would claim 5.33 board feet each: the nominal lie, quantified, is a 52 percent overstatement.

The firewood stack. A stack 8 ft long, 4 ft high, of 16 in logs (one and a third feet wide as stacked) measures 42.67 stacked cu ft, which is 0.33 cords, a face cord by the usual name, holding roughly 28 cu ft of solid wood by the mid-range yield. The full cord of the definition, 8 × 4 × 4 ft, is 128 cu ft exactly and about 85 cu ft of actual wood: the other 43 cu ft are the air you also paid to season.

Reading your results

Read board feet against the quote: lumber priced per board foot is checkable in one division, and a quote that used nominal dimensions somewhere will show it immediately. Read the weight as a logistics figure with a moisture asterisk: it is the dried estimate, and freshly milled or rain-soaked stock can run far heavier. Read the cord result as a measure of a stack, which is all a cord ever was: two sellers’ cords contain the same air-inclusive volume and honestly different amounts of wood.

Limitations

  • Board feet price volume, not usability. Knots, warp, checks and the ends you will trim are inside the board feet you pay for; a waste and defect allowance belongs on top for project planning, as with every material on this site.
  • Densities are typical, not certificates. Species vary by growing conditions and moisture content swings any density widely; the presets are published mid-range values for estimating loads and shipping, not for engineering.
  • Rough versus surfaced changes the input. The formula takes the dimensions as they are when measured; rough-sawn full-dimension stock genuinely is bigger, and its board feet honestly larger, than the surfaced equivalent.
  • Cord law varies by state. Many US states regulate firewood sales by the cord and its fractions with defined terms; the stack arithmetic here is universal, the sales vocabulary may not be.

Frequently asked questions

Why is a 2×4 not 2 by 4 inches?

It was, at the saw: rough green lumber is cut near full size, then drying shrinks it and planing (surfacing) smooths it to the standard finished size of 1.5 by 3.5 inches, which the industry kept calling by the rough name. The name is now a label, not a measurement, and every calculation on this page runs on measurements. The worked example prices the difference: board feet from the label would overstate the wood by about half.

How do I price a board sold by the piece against one sold by the board foot?

Convert the piece to board feet with this calculator, then divide its ticket price by that figure: the result is its effective price per board foot, comparable against any other board, size or yard. Wide, long and thick pieces often carry quietly higher per-foot prices, and thin project boards higher still; the conversion is the only honest way to see it, which is the entire reason the unit survives.

What is a face cord?

A face cord is a stack 8 ft long and 4 ft high whose depth is one log length, whatever that length is: with 16 in logs it is a third of a full cord, as the worked example shows. It is a customary term rather than a legal one in many places, which is why the calculator asks for the stack’s three real dimensions and reports full cords: buy the dimensions, not the name, and any stack can be compared with any other.

Why does the weight change so much with moisture?

Because a surprising share of fresh wood is water. Green lumber can carry moisture equal to half or more of its dry weight, and drying to furniture range removes most of it, so the same board feet can legitimately weigh 90 lb dry and 140 lb green. The density presets here are dried-wood values; for green or wet stock, expect the estimate to under-read, and for anything structural or vehicular, a scale outranks a table.

Related calculators

Method: board feet as thickness by width by length over twelve on actual dimensions, weight from stated species densities, cords as 128 cu ft of stacked volume with solid yield at the published mid-range. Last reviewed: 15 October 2026.