Lumber Calculator
Board feet, linear feet, framing studs, trim pieces, and siding coverage — all in one tool. Built-in wood species pricing, waste allowance as whole boards, and nominal vs actual dimension modes for every lumber purchase.
Dimension Basis
A 2×4 uses 2" × 4" even though it actually measures 1.5" × 3.5". Standard for softwood framing lumber.
Board Size
Waste Allowance
Material Pricing (Optional)
Select for quick reference pricing per board foot
Enter the supplier-listed nominal or billed size. Thickness and width use inches; length uses feet. If you know actual dressed dimensions (e.g. 1.5 × 3.5 for a 2×4), switch the dimension basis above. Always round up to whole boards — you cannot buy a partial board from a lumber yard.
Your Lumber Order
58.67
Board Feet
11 pieces · 88.0 linear ft
📋 Detailed Results
Board Feet per Piece
5.33 BF
Base Total Board Feet
10 × 5.33
53.33 BF
Total Linear Feet
8 ft × 10
80 ft
After 10% Waste
Effective waste rate: 10.0% (rounded up to whole boards)
Pieces to Order
10 base + 1 waste
11
Order Board Feet
11 × 5.33
58.67 BF
Order Linear Feet
88 ft
Volume (cubic ft)
4.889 ft³
📊 Material list
| Board group | Dimensions | Base | Order | Order BF | Cost |
|---|---|---|---|---|---|
| 2×4 · group 1 | 2 × 4 × 8 ft(nominal) | 10 | 11 | 58.7 | — |
Selected waste: 10%. Effective whole-board overage: 10.0%. Dimension basis: nominal / billed. Volume uses nominal dimensions. Verify supplier dimensions and pricing before ordering.
📏 Size Reference
| Nominal | Actual (dry) | BF @ 8ft |
|---|---|---|
| 2×4 | 1.5" × 3.5" | 5.33 |
| 2×6 | 1.5" × 5.5" | 8.00 |
| 2×8 | 1.5" × 7.25" | 10.67 |
| 2×10 | 1.5" × 9.25" | 13.33 |
| 2×12 | 1.5" × 11.25" | 16.00 |
| 4×4 | 3.5" × 3.5" | 10.67 |
| 6×6 | 5.5" × 5.5" | 24.00 |
✨More than just a board-foot total
Most lumber calculators give you one number and stop. This one is built for the whole journey — from picking the right dimension basis, through waste and species pricing, to how many whole boards you will actually carry to the checkout.
Four calculation modes
Board Feet, Framing (wall studs & plates), Board/Trim (pieces to buy), and Coverage (area to lineal feet). One tool handles every lumber question from material list to siding estimate.
Wood species pricing built-in
Select SPF, Douglas Fir, Red Cedar, Red Oak, White Oak, Hard Maple, Cherry, Black Walnut, and more — each with a 2026 national reference price per board foot. Override with your local yard quote for accuracy.
Nominal vs actual dimensions
Toggle between nominal/billed sizes (2×4 = 2" × 4") and actual/dressed sizes (2×4 = 1.5" × 3.5"). The calculator uses the correct basis for board-foot calculations depending on your supplier convention.
Waste as whole boards
Waste allowance rounds up to whole stock pieces — not decimal boards — so the order is actionable. A 10-board order with 10% waste becomes 11 boards, not 11.0.
⚡Quick answers
The lumber numbers people look for most, worked out with the same engine that powers the calculator above.
🪵
2×4 × 8 ft
5.33 BF
(2 × 4 × 8) ÷ 12 = 5.33 board feet
🏠
20 ft wall @ 16" OC
16 studs
floor(240 ÷ 16) + 1, add king/jack per opening
📐
85 ft trim → 12 ft boards
8 pieces
⌈85 ÷ 12⌉ = 8 stock lengths
🏗️
200 sq ft wall → 6" siding
436 LF
(200 × 12) ÷ 5.5 exposed = 436 lineal ft
💰
10 × 2×4×8 @ $3.50/BF
$186.67
10 × 5.33 BF = 53.3 BF × $3.50
♻️
10 boards + 10% waste
11 pieces
Waste rounded up to whole boards, not decimals
📝How to use the lumber calculator
Five steps from tape measure to lumber yard — the same workflow professional framers and estimators use to build a material list.
Pick your calculation mode
Four tabs cover the most common lumber questions: Board Feet for material lists, Framing for wall studs and plates, Board/Trim for pieces to order, and Coverage for siding or deck area converted to lineal feet.
Enter dimensions
Pick a preset size (2×4, 2×6, etc.) or type custom thickness and width. Choose nominal or actual dimensions depending on how your supplier quotes. Nominal is standard for softwood framing lumber; actual for hardwood and physical volume.
Add quantity and length
Enter how many boards you need and what stock length you will buy. Common framing lengths are 8, 10, 12, and 16 feet. For Framing mode, enter your wall dimensions and the calculator works out the stud and plate counts.
Set waste and pricing
Pick a waste preset (10% standard, 15% diagonal, 20% hardwood) or type your own. Add pricing by piece, linear foot, or board foot — or pick a wood species for reference pricing per BF.
Review your order
The results panel shows board feet, linear feet, pieces to order, volume in cubic feet, and estimated cost. Use the reference table to cross-check nominal vs actual sizes before you head to the lumber yard.
🧪The board foot formula, with worked examples
Every result on this page comes from one transparent equation — no black box. A board foot is a 144-cubic-inch volume unit: 1 inch thick, 12 inches wide, 1 foot long.
BF = ( T × W × L ) ÷ 12
- T — thickness in inches (nominal for softwood, actual for hardwood)
- W — width in inches (same basis as thickness)
- L — length in feet
- Total BF — BF per piece × number of pieces
Board feet are the standard volume unit for North American lumber pricing — especially hardwood. For softwood framing lumber (2×4s, 2×6s), suppliers usually price per piece at the nominal size, but the board-foot figure is still useful for comparing cost across different sizes.
Worked example: 20 × 2×4×8 boards
- T = 2 in, W = 4 in, L = 8 ft (nominal)
- BF per piece = (2 × 4 × 8) ÷ 12 = 5.33 BF
- Total for 20 boards = 20 × 5.33 = 106.6 BF
- With 10% waste: 106.6 × 1.10 = 117.3 BF
- Waste as whole boards: ceil(117.3 ÷ 5.33) = 22 pieces to order
- Cost @ $3.50/BF = 117.3 × $3.50 = $410.55
Nominal vs actual: the 117.3 BF above uses nominal dimensions (2\" × 4\"). In actual dressed sizes (1.5\" × 3.5\"), the same 22 boards give only 77.0 BF physical volume — but suppliers bill by nominal. Use the toggle in the calculator to match your supplier convention.
📐Board foot quick reference chart
Lookup table — nominal board feet for the most common framing sizes at stock lengths you will find at every lumber yard. All values use nominal dimensions per PS 20-25.
| Size | 8 ft | 10 ft | 12 ft | 14 ft | 16 ft |
|---|---|---|---|---|---|
| 1×4 | 2.67 | 3.33 | 4.00 | 4.67 | 5.33 |
| 1×6 | 4.00 | 5.00 | 6.00 | 7.00 | 8.00 |
| 1×8 | 5.33 | 6.67 | 8.00 | 9.33 | 10.67 |
| 2×4 | 5.33 | 6.67 | 8.00 | 9.33 | 10.67 |
| 2×6 | 8.00 | 10.00 | 12.00 | 14.00 | 16.00 |
| 2×8 | 10.67 | 13.33 | 16.00 | 18.67 | 21.33 |
| 2×10 | 13.33 | 16.67 | 20.00 | 23.33 | 26.67 |
| 2×12 | 16.00 | 20.00 | 24.00 | 28.00 | 32.00 |
Values = (T × W × L) ÷ 12 using nominal dimensions. Multiply by piece count, then add waste. Example: 20 × 2×4×10 = 20 × 6.67 BF = 133.3 BF; with 10% waste order ceil(133.3 × 1.10 ÷ 6.67) = 23 boards.
📏Nominal vs actual lumber dimensions
A 2×4 is not 2 inches by 4 inches after drying and planing. The dressed size is always smaller — and which basis to use depends entirely on how your supplier quotes.
| Nominal size | Actual dressed (dry) | Nominal BF @ 8 ft | Actual BF @ 8 ft |
|---|---|---|---|
| 1×4 | 0.75\" × 3.50\" | 2.67 BF | 1.75 BF |
| 1×6 | 0.75\" × 5.50\" | 4.00 BF | 2.75 BF |
| 1×8 | 0.75\" × 7.25\" | 5.33 BF | 3.63 BF |
| 1×12 | 0.75\" × 11.25\" | 8.00 BF | 5.63 BF |
| 2×4 | 1.50\" × 3.50\" | 5.33 BF | 3.50 BF |
| 2×6 | 1.50\" × 5.50\" | 8.00 BF | 5.50 BF |
| 2×8 | 1.50\" × 7.25\" | 10.67 BF | 7.25 BF |
| 2×10 | 1.50\" × 9.25\" | 13.33 BF | 9.25 BF |
| 2×12 | 1.50\" × 11.25\" | 16.00 BF | 11.25 BF |
| 4×4 | 3.50\" × 3.50\" | 10.67 BF | 8.17 BF |
| 4×6 | 3.50\" × 5.50\" | 16.00 BF | 12.83 BF |
| 6×6 | 5.50\" × 5.50\" | 24.00 BF | 20.17 BF |
PS 20-25 standard: the gap between nominal and actual is deliberate — green (fresh-cut) lumber is rough-sawn at nominal dimensions, then dried and planed (dressed) to the smaller finished size. Softwood suppliers bill by nominal for board-foot calculations. Hardwood dealers usually bill by actual dressed sizes. Always verify which basis your supplier uses.
Green vs dry lumber: the dressed sizes above are for dry lumber (moisture content ≤ 19% per PS 20-25). Green (unseasoned) lumber is slightly larger — a nominal 2×4 measures 1 9/16\" × 3 9/16\" green, versus 1½\" × 3½\" dry. Board feet use nominal regardless, so the BF tally stays the same; only physical volume and fit change.
Fraction ↔ Decimal (carpentry)
⚖️Linear feet, board feet, and square feet — what's the difference?
Three ways to measure lumber, each for a different job. Mix them up and you will either under-order or pay for wood you cannot use.
Linear Feet (LF)
Length only — one dimension
LF = sum of all piece lengths
Use for: Trim, fascia, handrail, any sold by the running foot
Example: Ten 8-ft 2×4s = 80 LF
Board Feet (BF)
Volume — thickness × width × length
BF = (T × W × Lft) ÷ 12
Use for: Hardwood, rough lumber, comparing cost across sizes
Example: Ten 8-ft 2×4s = 53.3 BF
Square Feet (SF)
Area — width × coverage width
SF = exposed face width (ft) × length (ft)
Use for: Sheathing, decking, siding coverage area
Example: Ten 8-ft 2×6 deck boards = 36.7 SF
Conversion tip: a 2×4 has 0.667 BF per linear foot. To convert $/LF to $/BF, multiply by 12 ÷ (T × W). To convert $/BF to $/LF, multiply by (T × W) ÷ 12. Same logic works for any size — just swap in the thickness and width.
♻️Waste factor by project type
The right waste percentage depends on how your boards are cut. Straight framing needs less than diagonal decking; premium hardwood needs the most. Always round up to whole boards.
| Project type | Waste % | Rationale |
|---|---|---|
| Simple shelving / straight cuts | 5% | Controlled end cuts, no complex geometry |
| Standard wall framing (16 OC) | 10% | Header and corner waste; AWC baseline |
| Floor framing (16 OC) | 10% | Joist trim waste; rim board offcuts |
| Perpendicular deck boards | 10% | End-cut waste only; boards lap squarely |
| Diagonal decking (45°) | 15–18% | Triangular perimeter waste |
| Fence with gate openings | 12% | Gate rough opening; ripped boards near posts |
| Hardwood furniture / cabinetry | 15–20% | Defect culling; grain-matching |
| Roof sheathing (standard pitch) | 10–12% | Hip and valley waste; fascia cuts |
Waste is applied to each board group and rounded up to a whole stock piece. Ten boards with 10% waste become 11 boards — not 11.0. This produces a slightly larger effective percentage on small quantities, but it means the order is actionable at the lumber yard.
🌲Wood species reference prices (2026 national averages)
Select a species in the calculator for automatic reference pricing per board foot. These are national averages — your local lumber yard, region, season, grade, and moisture content will all affect the actual quote.
| Species | Category | Price / BF | Common uses |
|---|---|---|---|
| SPF | Softwood | $3.50 | Framing, general construction |
| Douglas Fir | Softwood | $4.20 | Beams, columns, decking |
| Red Cedar | Softwood | $5.80 | Siding, decking, fences |
| Red Oak | Hardwood | $7.50 | Flooring, cabinets, furniture |
| White Oak | Hardwood | $8.20 | Barrels, flooring, furniture |
| Hard Maple | Hardwood | $9.00 | Flooring, butcher blocks |
| Cherry | Hardwood | $10.50 | Premium furniture, cabinets |
| Black Walnut | Hardwood | $14.00 | Fine furniture, gun stocks |
Price note: softwood framing lumber (SPF, Douglas Fir) is usually priced per piece, not per board foot, at big-box stores — a 2×4×8 might be $4–$7 each. The per-BF prices above work out to roughly $4.67–$9.33 per 2×4×8. Hardwood dealers almost always price by the board foot. Always ask your supplier which basis they use for both pricing and board-foot tallies.
💰How lumber is priced — and how to compare quotes
Three pricing bases are common in North America. Suppliers quote differently depending on species, grade, and product type. Knowing which basis you are quoted lets you compare apples to apples.
①Price per Piece
Standard for softwood framing lumber at big-box stores and commodity yards. A 2×4×8 is quoted at $X each regardless of board-foot content. Easy to estimate for known quantities.
Converting to $/BF: divide the piece price by the BF per piece. A $5 2×4×8 = $5 ÷ 5.33 = $0.94/BF — much lower than hardwood because softwood is a commodity.
②Price per Linear Foot
Common for specialty moldings, trim, and decking sold by the running foot. Useful when you know your project length but not the piece count yet.
Converting to $/BF: multiply the LF price by 12 ÷ (T × W). A 2×4 at $1.10/LF = $1.10 × 12 ÷ (2 × 4) = $1.65/BF.
③Price per Board Foot
Standard for hardwood, specialty softwood, and rough lumber from sawmills. The most universal basis — works across any size or length.
Converting to $/piece: multiply $/BF by BF per piece. Black Walnut at $14/BF × 5.33 BF = $74.62 per 2×4×8.
🏗️From square feet to lineal feet — the siding conversion
If you know how many square feet you need to cover but not how many linear feet of boards to buy, the Coverage mode has you covered. The key number is exposed face width — not nominal width.
Why exposed face width matters
Lap siding, shiplap, and board-and-batten all overlap — the exposed face width is less than the nominal board width. A 1×6 bevel siding board nominally measures 6 inches, but after installation and overlap only about 5.5 inches shows. Using the full 6 inches would under-count your material by about 8%.
For deck boards installed perpendicular to the joists with standard 1/8\" gaps, use the actual dressed width plus the gap. A 2×6 deck board (5.5\" actual) with 1/8\" gap covers 5.625 linear inches per board.
Siding presets — common exposed widths
6" Lap Siding (5.5" exposed)
1×6 bevel siding
8" Lap Siding (7.25" exposed)
1×8 bevel siding
12" Lap Siding (11.25" exposed)
1×12 bevel siding
Shiplap 1×6 (5.25" exposed)
1×6 shiplap
Shiplap 1×8 (7" exposed)
1×8 shiplap
Board & Batten (6" board)
Vertical board and batten
🏠How the framing count works
The Framing mode goes beyond board feet — it turns wall dimensions into a complete stud and plate takeoff, including king studs, jack studs, and cripple studs for each opening.
Stud count formula
- Convert wall length to inches: 20 ft = 240 inches
- Divide by stud spacing: 240 ÷ 16 = 15 bays
- Add 1 for the end stud: 15 + 1 = 16 common studs
- Per door/window: add 2 king studs + 2 jack studs + 2 cripple studs
- Total studs = common + kings + jacks + cripples
A 24-inch on-center spacing reduces stud count by about 33% but requires structural engineering for most applications. IRC code allows 24\" OC for non-load-bearing interior walls in some jurisdictions.
Plate calculation
- Sole plate: one full-length board per wall section
- Top plate (single): one full-length board per wall section
- Double top plate: two full-length boards per wall section (IRC R602.3.2)
- Pieces to buy: ceil(wall length ÷ stock length) per layer
Note: this calculator does not size headers, beams, or footings — that is a structural engineering question. Always check local building codes and consult a structural engineer for load-bearing calculations.
🔧Real projects, worked out step by step
Three typical jobs — a deck, a wall, and a fence — with the math you would run on the way to the lumber yard. Each example starts from a project size and ends with a board count you can actually buy.
🛠️12×16 Deck with 2×6 decking
- Deck area: 12 × 16 = 192 sq ft
- 2×6 actual width = 5.5 in = 0.458 ft
- Boards before waste: 192 ÷ (0.458 × 16) = 26.2 → 27
- +10% waste (perpendicular decking) → ceil(27 × 1.10) = 30 boards
- BF per board: (2 × 6 × 16) ÷ 12 = 16 BF
- Total BF: 30 × 16 = 480 BF
- Cost @ $4.20/BF (Douglas Fir) = 480 × $4.20 = $2,016
💡 Order 30 boards of 2×6×16. Add joists, beams, posts separately.
🏠20-ft interior wall at 16" OC
- Wall length: 20 ft = 240 inches
- Common studs: floor(240 ÷ 16) + 1 = 16 studs
- With one door: +2 king studs + 2 jack studs + 2 cripples = 22 total
- Plates: sole + double top = 3 × 20 = 60 LF of 2×4
- Stud BF: 22 × (2×4×8 BF) = 22 × 5.33 = 117.3 BF
- Plate BF: ceil(60 ÷ 8) × 3 × 5.33 = 8 × 3 × 5.33 = 127.9 BF
- Total framing BF ≈ 245 BF @ $3.50/BF = $857.50
💡 Buy 22 stud-length 2×4s, 8 plates, and a header. Don't forget sheathing.
🚧50-ft privacy fence with 1×6 pickets
- Picket gap: 1/4 in, so effective spacing = 5.75 in
- Pickets before waste: 50 × 12 ÷ 5.75 = 104.3 → 105 pickets
- +8% waste (straight pickets, no gate) → ceil(105 × 1.08) = 114 pickets
- Picket BF: (1 × 6 × 6) ÷ 12 = 3 BF each × 114 = 342 BF
- Rails: 2 rails × 50 ft = 100 LF of 2×4 = 8 boards
- Posts: 50 ft ÷ 8 ft spacing = 7 posts of 4×4
💡 114 pickets + 8 rails + 7 posts. Add a gate if your layout calls for it.
These examples use nominal dimensions for softwood board-foot calculations (per PS 20-25), the waste percentages from the table above, and stock lengths divisible into the piece count. Your actual takeoff will vary with local lumber stock, board lengths, and whether you buy piece-count or board-foot.
❓Frequently asked questions
Everything people ask before heading to the lumber yard.