Board Foot Calculator

What is a board foot?

A board foot is a unit of lumber volume equal to 144 cubic inches — the volume of a piece 12 inches wide, 12 inches long, and 1 inch thick. It exists because hardwood and large-dimension timber are sold in random widths and lengths where a simple piece count or linear foot measurement would not reflect the actual volume being purchased.

Understanding board feet matters any time you purchase wood that varies in width, thickness, or length. Every hardwood species at every lumber yard is priced per board foot. Sawmills quote custom timber orders in MBF (thousand board feet). Even when you buy standard softwood dimensional lumber at a big-box retailer by the piece, the underlying wholesale price was originally set on a board foot basis — the retailer just pre-calculated it for you.

Use nominal dimensions — the labeled size at the lumber yard, not the actual milled dimensions. A 2×6 board is entered as 2 inches thick and 6 inches wide even though it actually measures 1.5 × 5.5 inches after milling. The formula uses nominal figures because lumber has been sold and priced on nominal dimensions since before milling standards were established, and the convention persists throughout the industry. For your own reference and a deeper explanation of this topic, see the board feet guide.

Board feet per piece — quick reference

These figures are the exact board foot yield per piece for the most common lumber sizes at the most common retail lengths, calculated using the standard formula. Use this table to cross-check your order quantities or estimate project volumes without running the calculator each time.

The 2×6 at any length is the easiest to verify mentally because its board foot yield equals its length in feet exactly: a 12-foot 2×6 = 12 BF, a 16-foot = 16 BF. For any 2× lumber, multiply the width by the length and divide by 12 to get the yield per piece. For 4× and 6× timber, the BF per linear foot is notably higher — a 16-foot 6×6 contains 48 BF, the equivalent of three 16-foot 2×6s.

When ordering a project's lumber list, calculate each line item separately and sum the totals. The lumber cost calculator handles multi-line orders and converts BF totals to a cost figure once you have your species price.

Nominal vs actual dimensions

Every piece of dimensional lumber sold at retail has two sets of dimensions: the nominal size (what the label says and what you use in the board foot formula) and the actual milled size (what your tape measure shows). The gap exists because the nominal size refers to the rough-sawn dimension before kiln drying and surface planing remove material.

The nominal/actual gap matters in two contexts: board foot calculations (always use nominal) and physical coverage calculations (always use actual). When calculating how many 5/4×6 deck boards you need to cover a 200 sq ft deck, use the actual 5.5-inch width. When calculating how many board feet those same boards contain for a lumber order or pricing comparison, use the nominal 6-inch width. Conflating the two produces material shortages or over-ordering depending on which way you get it wrong.

For deck board and fence board coverage calculations, the lumber quantity calculator handles actual dimensions automatically when calculating piece counts.

MBF — what it means and when it applies

MBF stands for thousand board feet (the M comes from the Roman numeral for 1,000). It is the standard unit for wholesale lumber pricing, sawmill contracts, and large construction procurement. When a sawmill quotes $900 per MBF for Douglas Fir, they mean $0.90 per board foot — or $900 for a 1,000 BF order.

Retail lumber buyers rarely encounter MBF pricing directly — it shows up when working with independent sawmills, hardwood dealers, or timber suppliers who price by volume rather than by piece. If you are pricing a large order of timber for a post-and-beam build or a significant hardwood purchase, ask for the MBF rate and use this calculator to confirm the BF volume of your order before committing. For bulk structural timber volume calculations, the timber volume calculator handles large-section timber and log rounds where board feet and cubic feet both matter.

Hardwood pricing by species

Hardwood prices reflect species rarity, NHLA grade, board width, and current market conditions. FAS (Firsts and Seconds) is the highest grade — clear faces with no defects over the required cutting area. No. 1 Common allows some defects and runs significantly lower. Prices below are retail kiln-dried figures from primary hardwood dealers as of early 2026.

Two width surcharges apply across all hardwood species: boards wider than 9 inches typically carry a $1–$2/BF premium, and boards wider than 11.5 inches carry an additional $1–$2/BF surcharge. Wide, clear planks are statistically rare in secondary-growth forests, and the pricing reflects that directly. When budgeting a project that requires wide boards, account for the width premium — a 12-inch wide walnut board is priced meaningfully higher per board foot than the same walnut at 7 inches.

For exterior decking, Ipe is sold per square foot rather than per board foot because it is always sold in a standard 1-inch thickness. At $16.69–$17.80/SF, a 400 sq ft Ipe deck costs roughly $6,700–$7,100 in decking boards alone — before framing, fasteners, or labour. The fence board calculator also uses board foot volume when calculating cedar and exotic fence board orders.

Board feet vs linear feet

Linear footage measures only length — width and thickness are ignored. A 12-foot 2×4 and a 12-foot 2×12 are both 12 linear feet, but they contain 8 BF and 24 BF respectively. Linear footage is the right measure when you already know the size and want to know how many feet of it you need. Board footage is the right measure when you are pricing or comparing lumber where width and thickness vary.

The correct measure depends on what you are trying to find out. If you are asking "how many boards do I need to frame this wall?" — linear feet, with the size already determined. If you are asking "how much will this hardwood order cost at $9/BF?" — board feet, because you need volume, not just length. The two units answer different questions and are not interchangeable.

For projects requiring framing lumber quantity calculations — how many 2×4s, 2×6s, and 2×8s you need for a specific structure — the lumber quantity calculator handles piece counts and linear feet automatically. Once you have the piece count, come back here to verify the BF total for comparison against a bulk price quote.