Getting thickness, width and length right before you calculate
Board feet is a volume measure — thickness × width × length — so a small error in any one dimension moves the answer proportionally. Here's how to feed it real numbers.
Decide nominal or actual
If you're quoting a supplier's stock list or a framing takeoff, use the nominal size printed on the tag (a "2x4" is nominal, even though it doesn't measure 2" by 4"). If you're working from a board already in hand — measure it with calipers and use Actual mode instead.
Measure thickness and width
Thickness is the board's smaller cross-section dimension, width the larger — both in inches. For rough hardwood, thickness is often quoted in quarters (4/4 = 1", 8/4 = 2"); use the Quick Size dropdown to skip the conversion.
Enter length and quantity
Length is the full end-to-end length of one board — feet is the standard unit, but inches, cm and mm all work. Quantity is how many identical boards you're buying or have on the cut list.
Add waste and a price, if you have one
Open Advanced to add an overage percentage for culls and cutting waste, and a price per board foot to get a total cost. Both are optional — the core board footage calculates without them.
The five formulas behind every result
Nothing on this page is a black box. Here's exactly what runs when you change a number.
Board Feet (per board)
Thickness and width in inches, length in feet. One board foot equals 144 cubic inches of wood — a 1"-thick, 12"-wide, 1'-long piece.
Total Board Feet
Per-board footage times how many identical boards you're buying or cutting.
Order Quantity (with waste)
Inflates the net footage you need by an overage factor to cover culls, warp, knots and saw kerf, then rounds up to the next whole board foot for ordering.
Total Cost
Based on the waste-adjusted order quantity, since that's what you'll actually be billed for — not just the net footage the project consumes.
Volume Check
A quick sanity check and a useful cross-reference figure when a supplier quotes by cubic footage instead of board footage.
Ordering rough oak for a stair handrail
Same five formulas, filled in step by step, for 4 pieces of 8/4 red oak — a realistic order for a curved handrail blank — 6" wide, 8' long, at $6.50 per board foot.
Board feet per board
8/4 rough stock measures 2" nominal thickness. BF = (2 × 6 × 8) ÷ 12 = 96 ÷ 12 = 8 bd ft per board. Note this uses the nominal 2", not the roughly 1.75"–1.875" it will actually measure after surfacing.
Total board feet
8 bd ft × 4 boards = 32 bd ft of net footage — the amount the handrail blank actually consumes once it's cut and surfaced.
Order quantity with waste
Rough figured hardwood like this commonly needs 15% overage for knots, warp and grain-matching culls: 32 × 1.15 = 36.8, rounded up to 37 bd ft to order. This is the number you actually call in to the yard — not the 32 bd ft from step 2.
Total cost
37 bd ft × $6.50/bd ft = $240.50. Pricing off the net 32 bd ft instead would understate the real bill by over $32 — the waste factor from step 3 cascades directly into the number on the invoice.
This is why Order Quantity and Total Cost in the results strip are always based on the waste-adjusted figure, not the raw total — the raw total tells you what the project needs, the order quantity tells you what to actually buy.
Why a "2x4" isn't 2" by 4"
Dimensional softwood lumber is milled from a rough nominal size, then surfaced (planed) on all four sides — which removes roughly 3/8"–3/4" per dimension. Board footage on framing lumber is still priced and calculated using the nominal size, not the smaller actual size.
| Nominal Size | Actual (Surfaced) Size | Board Feet per Linear Foot |
|---|---|---|
| 1x4 | 3/4" × 3-1/2" | 0.33 bd ft/ft |
| 1x6 | 3/4" × 5-1/2" | 0.50 bd ft/ft |
| 1x8 | 3/4" × 7-1/4" | 0.67 bd ft/ft |
| 1x10 | 3/4" × 9-1/4" | 0.83 bd ft/ft |
| 1x12 | 3/4" × 11-1/4" | 1.00 bd ft/ft |
| 2x4 | 1-1/2" × 3-1/2" | 0.67 bd ft/ft |
| 2x6 | 1-1/2" × 5-1/2" | 1.00 bd ft/ft |
| 2x8 | 1-1/2" × 7-1/4" | 1.33 bd ft/ft |
| 2x10 | 1-1/2" × 9-1/4" | 1.67 bd ft/ft |
| 2x12 | 1-1/2" × 11-1/4" | 2.00 bd ft/ft |
| 4x4 | 3-1/2" × 3-1/2" | 1.33 bd ft/ft |
| 6x6 | 5-1/2" × 5-1/2" | 3.00 bd ft/ft |
This table covers softwood dimensional lumber. Rough hardwood works differently — see the size reference below for quarter-thickness (4/4, 8/4) notation.
Rough hardwood quarter-thickness notation
Hardwood is typically sold rough-sawn and priced by the quarter-inch of nominal thickness, not by 1x/2x labels. Width and length are usually random and measured per board, then totaled.
| Quarter Notation | Nominal Thickness | Typical S2S Finished Thickness |
|---|---|---|
| 4/4 | 1" | 13/16" [VERIFY: confirm surfaced thickness with your specific mill/grade] |
| 5/4 | 1-1/4" | 1-1/16" [VERIFY] |
| 6/4 | 1-1/2" | 1-5/16" [VERIFY] |
| 8/4 | 2" | 1-3/4" [VERIFY] |
| 12/4 | 3" | 2-3/4" [VERIFY] |
Board footage on rough hardwood is calculated using the nominal (rough) thickness, same as softwood — surfacing loss reduces the wood you get, not the footage you're billed for. Actual surfaced thickness varies by mill; confirm with your supplier before ordering to a tight tolerance.
Ordering, rounding & mixed-size cut lists
Getting the board-foot math right is only half the job — three things below decide whether the number you calculate matches the number on the invoice.
Per-board vs. total rounding
Rounding each board up individually before summing almost always produces a larger total than summing exact values and rounding once at the end — the gap grows with more, shorter boards. Know which method your supplier uses before comparing quotes.
Mixed-size cut lists
A real project rarely uses one board size. Run each distinct size through this calculator separately and add the Total Board Feet results together — the per-board and per-size figures don't average meaningfully on their own.
Waste factor by material
[VERIFY: these are commonly cited planning ranges, not a fixed standard — confirm against the specific grade and species you're buying]. Clear, straight-grained stock needs less; anything with heavy figure, curved parts, or strict grain-matching needs more.
Board feet vs. linear feet pricing
Big-box stores commonly price dimensional lumber per linear foot or per piece; hardwood yards price by the board foot. Convert one to the other using the board-feet-per-linear-foot column in the nominal size table above before comparing a quote.
This calculator handles one board size at a time. For a project cutting several different sizes, run each size through separately and total the results — see Mixed-Size Cut Lists above.
Common mistakes when calculating board feet
Most quote mismatches and order shortfalls trace back to one of these five errors, not to a wrong formula.
Using actual dimensions for a nominal order
Plugging in the true 1.5" × 3.5" of a surfaced 2x4 instead of the nominal 2" × 4" understates board footage against what the supplier is actually pricing and shipping you.
Confusing board feet with square feet
Square footage ignores thickness entirely. A 1" thick and a 2" thick board covering the same floor area have very different board footage — and very different prices.
Skipping the waste factor on rough or figured stock
Net project footage isn't what you should order. Culls, warp, and defects in rough-sawn hardwood routinely eat 15–25% of what's cut from the log before it reaches you.
Summing rounded boards instead of rounding the sum
Rounding each board up individually, then adding, produces a noticeably larger total than adding exact values and rounding once — the gap compounds with a long cut list.
Mixing board-foot and linear-foot pricing
A quote in dollars per linear foot isn't directly comparable to one in dollars per board foot unless you convert through the board's actual cross-section first.
Pricing off net footage, not order footage
The bill reflects what you bought, including waste overage — not just what the finished project consumes. Price the Order Quantity result, not the Total Board Feet result.
When to use a board feet calculator
Board footage shows up anywhere lumber is priced or specified by volume rather than by the piece.
Furniture & Woodworking
Sizing a rough-lumber order for a table, handrail blank, or newel post before a shop visit.
Getting a Supplier Quote
Working out expected footage before calling a hardwood yard, so a quoted price can be sanity-checked.
Framing Takeoffs
Converting a stick count into total board footage for a materials budget or comparison between suppliers.
DIY Project Budgeting
Estimating total lumber cost for a stair, deck, or built-in before committing to the project.
Cut List Conversion
Turning a multi-size cut list into a single order-quantity figure, one size run at a time.
Comparing Pricing Models
Checking whether a big-box linear-foot price actually beats a lumberyard's board-foot price for the same stock.