Lumber Calculator

A board foot is a unit of volume equal to one square foot of lumber one inch thick. It's the standard measurement for lumber in North America. For example, a 2×6 board that is 12 feet long contains 12 board feet. The formula is (Thickness × Width × Length) ÷ 12, where all dimensions are in inches except length which is in feet.

Lumber is sold by nominal (labeled) dimensions, but the actual dimensions are smaller due to the milling, planing, and drying process. A "2×4" is actually 1.5" × 3.5". This standardization has been in place for over a century and is defined by the American Lumber Standard Committee. Always use actual dimensions for accurate calculations of material volume and weight.

Multiply the total board feet by the price per board foot for your chosen wood species. For example, if you need 50 board feet of oak at $9 per board foot, your material cost would be $450. This calculator performs this calculation automatically based on the species selected. Keep in mind that actual lumber prices vary by location, supplier, and quality grade.

The choice depends on your project requirements and budget. Pine is affordable and soft, ideal for framing and general carpentry. Oak is harder and has attractive grain, good for furniture and flooring. Maple is dense and durable, excellent for high-traffic areas. Walnut is prized for fine furniture due to its rich color and workability. Cherry offers beautiful appearance at moderate cost. Cedar is naturally rot-resistant, perfect for outdoor projects.

Weight varies significantly by species and moisture content. Pine weighs about 35 pounds per board foot, oak about 47 pounds per board foot, and cedar about 28 pounds per board foot. This calculator provides weight estimates based on typical kiln-dried lumber at 12% moisture content. Green (freshly cut) lumber weighs much more due to water content and should not be used for structural calculations.

Rough lumber has an unfinished surface with saw marks and irregular texture. Surfaced lumber (S4S - Surfaced Four Sides) has been planed smooth on all four sides and has the actual dimensions most people are familiar with. Most retail lumber is surfaced. Rough lumber is typically slightly larger in actual dimensions but harder to work with. Always check your supplier to confirm which you're receiving.

Start by sketching your project and measuring all components. Calculate linear feet for each piece, then sum the total. Divide total linear feet by your lumber length to get the number of pieces needed, then calculate board feet. Always order 5-10% extra to account for mistakes, waste from cutting, and potential defects. This calculator helps verify your estimates once you've determined your piece count.

Common grades include Select (best appearance, highest price), No. 1 Common (good quality, fewer defects), No. 2 Common (utility grade, more knots), and lower grades for structural use only. Grade affects appearance, strength, and stability. Most DIY projects use No. 2 Common or better. Structural lumber has different grading based on strength ratings. Ask your supplier to help select the appropriate grade for your specific project needs.

This calculator is designed for solid sawn lumber with standard nominal dimensions. Plywood is measured in sheets (typically 4×8 feet) rather than board feet. Some engineered lumber products have non-standard dimensions. For these materials, calculate square footage and purchase by sheet count instead. Your lumber supplier can help convert your project needs to the appropriate material format.

Cedar, redwood, and pressure-treated lumber are excellent for outdoor use. Cedar and redwood naturally resist rot and insects. Pressure-treated lumber has chemicals injected to provide protection and is the most affordable option for outdoor framing. For maximum longevity, consider tropical hardwoods like ipe or cumaru, though they're expensive. Always ensure you're using exterior-grade materials rated for ground contact if needed.