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Construction

Lumber Calculator: Board Feet & Costs

By Nick Major · Founder, Calculator Campus Last updated April 27, 2026

The lumber calculator estimates board feet for one group of identically sized boards. Enter quantity, thickness, width, and length to get net board feet, MBFT, and total lineal feet. Add a waste/overage percentage and an optional price per board foot or per MBFT to estimate the order quantity and material cost.

Important: Informational only. Double-check any value that affects a real decision before acting on it.
Inputs

Adjust your numbers

Results update as you type.

Count of identical boards in this line item. Use 0 only to clear the calculation.
Enter the actual or quoted thickness in inches. A dressed 2x board is often 1.5 in thick.
Enter the actual or quoted width in inches. A dressed 2x6 is often 5.5 in wide.
Board length in feet. If your length is in inches, divide by 12 first.
Optional planning buffer for cuts, defects, and mistakes. Many projects use 10–15%.
Optional lumber price. Leave blank to skip the cost estimate.
Use per board foot for retail quotes or per MBFT for wholesale-style quotes.

Assumptions

  • Thickness and width are entered in inches; length is entered in feet.
  • All boards in this calculation have the same dimensions.
  • Board-foot math uses the standard BF = thickness × width × length ÷ 12 relationship.
  • Waste/overage is added after calculating net board feet and before cost.
  • The calculator does not determine structural suitability, span, grade, or building-code compliance.
Results

Live answer

Order board feet —
Net board feet —
Board feet per board —
Order MBFT —
Lineal feet —
Waste / overage —
Estimated cost —
How it works

Assumptions and detail

Adds the board-foot, MBFT, and lineal-foot outputs seen in the research bundle, plus optional waste and per-BF/per-MBFT pricing without turning the page into a full building-materials estimator.

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How the math works

The formulas and what each part means

Board feet per board 
BF = (T * W * L) / 12

Length is in feet while width and thickness are in inches; the divisor 12 reconciles the mixed units so the result is in board feet (1 BF = 144 cubic inches = 1/12 cubic foot).

Total board feet (BDFT) 
BDFT = N * BF

Multiplies the per-board board footage by the number of boards.

Order board feet with waste 
Order_BDFT = BDFT × (1 + waste% / 100)

Use 0% waste to keep order board feet equal to net board feet.

Thousand board feet (MBFT) 
MBFT = Order_BDFT / 1000

The page shows MBFT from the order quantity after optional waste/overage.

Total lineal feet (LF) 
LF = N * L

Sum of board lengths regardless of cross-section.

Total cost 
Total_cost = Order_BDFT × price_per_BF; if quoted per MBFT, price_per_BF = price_per_MBFT / 1000

Computed only when a price is supplied and based on the selected price unit.

SymbolNameUnitDescription
BF Board Feet board feet The volume of a single board expressed in board feet, calculated from its thickness, width, and length.
T Thickness inches The thickness of a single board measured in inches.
W Width inches The width of a single board measured in inches.
L Length feet The length of a single board measured in feet.
BDFT Total Board Feet board feet The total board footage for all boards combined, calculated by multiplying the per-board board footage by the number of boards.
N Number of Boards The count of boards included in the calculation.
MBFT Thousand Board Feet thousand board feet The total board footage expressed in the standard wholesale unit of one thousand board feet.
LF Linear Feet feet The total linear footage of all boards combined, summing their lengths regardless of cross-sectional dimensions.
Total_cost Total Cost dollars The total purchase cost for all boards, computed only when a price per board foot is provided.
P Price per Board Foot dollars per board foot The cost per board foot used to calculate the total price of the lumber order.
Order_BDFT Order Board Feet board feet Net board feet plus optional waste or overage.
WASTE% Waste Percentage percent Planning buffer applied to net board feet before cost.
P_mbft Price per MBFT dollars per MBFT Price quoted per thousand board feet; divided by 1000 to get price per board foot.
Methodology

How the answer is computed

The calculator uses the standard board-foot formula BF = thickness(in) × width(in) × length(ft) ÷ 12. It multiplies per-board BF by quantity for net board feet, adds the optional waste percentage, converts the order quantity to MBFT by dividing by 1,000, and multiplies by either a per-BF price or a per-MBFT price converted to per-BF.

Worked examples

See the math step by step

Single Oak Board for a Shelf

Result — value: 8 · unit: board feet · interpretation: One 2x6x8 oak board contains 8 board feet of lumber.

Deck Build with 20 Pressure-Treated Boards and Total Cost

Result — value: 577.50 · unit: dollars · interpretation: 20 pressure-treated 1.5x5.5x12 deck boards cost $577.50 at $3.50 per board foot.

When to use this calculator

Use this calculator when pricing a run of deck boards, fence pickets, trim, hardwood boards, or framing lumber that shares one set of dimensions. For mixed lots, run one line item at a time and add the results. It is not a framing takeoff, span checker, or structural design tool.

Understanding Board Feet

Board feet measure lumber volume, not surface area or length alone. One board foot equals 144 cubic inches: a board one inch thick, twelve inches wide, and twelve inches long. This calculator keeps the common lumber-yard convention of width and thickness in inches with length in feet, so BF = thickness × width × length ÷ 12.

Waste and Overage

Waste covers cutoffs, defects, mistakes, and boards you reject on site. A simple deck or shelf may only need a modest buffer, while projects with many short cuts can need more. The waste field increases the board-foot order quantity and the cost estimate, but it is still a planning assumption to confirm against your cut list.

Assumptions

What we assume

  • Thickness and width are entered in inches; length is entered in feet.
  • Inputs should be actual or supplier-quoted dimensions when cost accuracy matters; nominal labels such as 2x4 may differ from dressed size.
  • All boards in a single run share the same width, thickness, and length.
  • Waste/overage is added after net board feet and before MBFT and cost are calculated.
  • The price field is interpreted using the selected price unit: per board foot or per MBFT.
Limitations

What this skips

  • Does not perform a whole-project takeoff or calculate stud, joist, rafter, or header counts.
  • Does not check structural adequacy, grade, span tables, loads, or local building-code requirements.
  • Does not account for supplier bundle sizes, delivery minimums, taxes, or regional price changes.
  • Does not calculate sheet goods such as plywood or OSB, which are usually sold by the sheet.
  • Does not model saw kerf pattern-by-pattern; use the waste/overage field as a planning buffer.
Common mistakes

What people miss

  • Entering length in inches instead of feet.
  • Using nominal dimensions when the supplier prices or invoices by actual dressed size.
  • Mixing linear feet and board feet in the same entry.
  • Forgetting to add a waste/overage buffer for cutoffs and rejected boards.
  • Entering an MBFT quote as if it were a per-board-foot price.
  • Trying to use board-foot volume as a substitute for span or structural design checks.
References

References

  1. Valuing Standing Timber

    Penn State Extension · accessed 2026-04-27

  2. Weights & Measurement

    American Wood Council · accessed 2026-04-27

  3. How do I convert to metric lumber sizes?

    American Wood Council · accessed 2026-04-27

  4. Board Foot Calculator

    Omni Calculator · accessed 2026-04-27

  5. Free Lumber Calculator - Pieces to Board Footage and Pricing

    Wisconsin Lumber & Pallet · accessed 2026-04-27

Frequently asked questions

What does a lumber calculator do and who is it for?
A lumber calculator estimates how much wood you need for a project based on the dimensions and quantity you enter, converting those inputs into a total board footage or linear footage figure. It is useful for homeowners, contractors, and woodworkers who want to plan material purchases accurately and avoid costly over- or under-buying. Whether you are framing a wall, building a deck, or crafting furniture, the tool handles the repetitive math so you can focus on the project itself.
What is a board foot and how is it different from a linear foot?
A board foot is a unit of lumber volume representing a piece that is one foot long, one foot wide, and one inch thick, and it is the standard measure used to price dimensional lumber. A linear foot, by contrast, simply measures length along one dimension without accounting for width or thickness. Knowing which unit your supplier uses is important because pricing and ordering quantities are based on different measurements depending on the lumber type.
Does the calculator account for waste, defects, or cutting errors?
The calculator produces a theoretical quantity based on your project dimensions alone and does not automatically include any allowance for waste from saw cuts, knots, warped boards, or measurement mistakes. Most builders add a buffer on top of the calculated total to avoid running short partway through a project. The appropriate buffer depends on your skill level, the complexity of the cuts involved, and the grade of lumber you are purchasing.
Should I use nominal or actual lumber dimensions when entering measurements?
You should use the actual finished dimensions of the lumber, not the nominal label printed on the tag, because milling and drying reduce a board to smaller than its stated size. A piece sold as two-by-four, for example, has actual dimensions that are noticeably smaller than two inches by four inches. Using nominal sizes will overestimate the volume of each board and produce an inaccurate total for your project.
What does the lumber calculator result not tell me?
The result tells you quantity of material but says nothing about whether that lumber is structurally adequate for your intended use, load-bearing requirements, or local building codes. It also does not account for fasteners, adhesives, hardware, or the labor involved in the project. For any construction that affects structural integrity or requires a permit, consult a licensed engineer or contractor to confirm the design meets safety standards.