Calculate board feet for any lumber dimension, look up wood species data, and estimate project costs — all in real time. Switch between single board measurements and standard nominal lumber sizes with one tap.
Pro tip: A “board foot” is always based on rough-sawn thickness, not surfaced (S4S) thickness. When you buy 4/4 lumber, you’re paying for a full 1″ of thickness even though the surfaced board measures only ¾″. That missing ¼″ went through the planer — you already paid for it.
Species Comparison
Rough-Cut Waste Planner
Hardness Recommendation Engine
How to Calculate Board Feet
A board foot is the standard unit of volume used to buy and sell hardwood lumber in North America. One board foot equals a piece of wood 1 inch thick, 12 inches wide, and 12 inches long — or 144 cubic inches of material. The formula is straightforward:
Board Feet = (Thickness × Width × Length) ÷ 144
All three measurements must be in inches. If your length is in feet, multiply by 12 first, or use the shortcut formula: (T″ × W″ × L′) ÷ 12. Multiply by the number of boards for a total. Enter your dimensions in the calculator above and the result updates in real time — no button to press.
Nominal vs Actual Lumber Dimensions
Dimensional lumber at the home center is sold by its nominal size, which is always larger than the actual size you receive. A 2×4 does not measure 2 inches by 4 inches — it measures 1½″ × 3½″ after drying and planing. This naming convention dates back to when lumber was sold as rough-sawn at its full nominal dimensions; modern processing removes material.
- 1×4 → ¾″ × 3½″
- 1×6 → ¾″ × 5½″
- 1×8 → ¾″ × 7¼″
- 2×4 → 1½″ × 3½″
- 2×6 → 1½″ × 5½″
- 2×10 → 1½″ × 9¼″
- 4×4 → 3½″ × 3½″
- 6×6 → 5½″ × 5½″
Board feet for dimensional lumber are traditionally calculated using the nominal dimensions, not the actual. When you buy a 2×4×8′, the lumber yard charges you for (2 × 4 × 96) ÷ 144 = 5.33 board feet even though the actual volume is less. This calculator handles both systems — select Nominal Lumber mode and it auto-fills everything for you.
Understanding the Quarter System: 4/4, 5/4, 6/4, 8/4
Hardwood lumber is sold using a “quarter” thickness system that describes the rough-sawn thickness in quarters of an inch. 4/4 (pronounced “four-quarter”) means 1 inch thick, 5/4 is 1¼ inches, 6/4 is 1½ inches, and 8/4 is 2 inches.
After surfacing (planing smooth on both faces), a 4/4 board typically measures ¾″ to 13/16″, a 5/4 board around 1–1-1/16″, and 8/4 around 1¾″. Always specify whether you want rough or surfaced lumber, and remember that board foot pricing is based on the rough thickness. The planer waste is built into the price.
The Janka Hardness Scale Explained
The Janka hardness test measures a wood species’ resistance to denting by recording the force (in pounds-force, lbf) needed to embed a .444-inch steel ball to half its diameter into the wood. Developed by Gabriel Janka in 1906, it remains the worldwide standard for comparing wood hardness.
For flooring, most professionals recommend species above 1,000 lbf — Red Oak (1,290 lbf) is the traditional benchmark. For furniture and cabinetry, softer woods like Cherry (950 lbf) or Walnut (1,010 lbf) are perfectly adequate. Exotic species like Ipe (3,680 lbf) are nearly indestructible but extremely difficult to work with hand tools and dull blades quickly.
- Very Soft (under 600 lbf): Basswood, Pine, Cedar — easy to carve, dent easily
- Soft to Medium (600–1,000 lbf): Poplar, Cherry, Walnut — good all-purpose
- Hard (1,000–1,500 lbf): Oak, Maple, Ash — excellent for high-traffic surfaces
- Very Hard (1,500+ lbf): Hickory, Purpleheart, Ipe — specialty and outdoor use
How to Buy Hardwood Lumber: Grading, Pricing, and Selection
Unlike dimensional softwood lumber (2×4s and plywood) sold at home centers, hardwood lumber is priced per board foot and graded by the National Hardwood Lumber Association (NHLA). The two most common grades you will encounter are FAS (First and Seconds) and Select & Better, which guarantee large clear (defect-free) areas. Lower grades like #1 Common and #2 Common have more knots and sapwood but cost 30–50% less.
Prices per board foot vary widely by species, grade, and region. Domestic staples like Poplar run $3–$5/BF, Red Oak $5–$8/BF, and Black Walnut $8–$14/BF at retail. Exotics like Purpleheart or Wenge can exceed $15/BF. Enter your local price in the calculator above to get an accurate cost estimate. Always buy 10–15% more than your calculation to account for defects, miscuts, and grain matching.
Weight of Wood: Why It Matters for Your Project
Wood density directly affects shipping cost, structural load calculations, tool selection, and workability. A tabletop made from Ipe (69 lb/ft³) will weigh nearly three times as much as the same top in Eastern White Pine (25 lb/ft³). The weight estimates in this calculator are based on air-dried density at approximately 8% moisture content, which is typical for kiln-dried lumber ready for indoor use.
Green (freshly cut) wood can weigh roughly twice as much as kiln-dried wood of the same species because it is saturated with water. If you are transporting green lumber from a sawmill, double the weight estimate from this calculator for planning purposes. As wood dries, it also shrinks — typically 6–8% across the grain — which is why rough-sawn lumber is cut oversized.
Need to estimate other building materials? Browse the full suite of Home & Real Estate calculators for flooring, drywall, paint, concrete, and more project planning tools.