Lumber Calculator
Pieces = run ÷ on-centre spacing, rounded down, plus one, times the number of rows; lineal feet = pieces × the length of each piece. A 40 ft wall at 16 in on centre with 9 ft studs takes 31 pieces and 279 lineal ft, or 33 pieces with 5% waste. For a full wall take-off, use the Framing Calculator.
How it's calculated: Pieces = (⌊run ÷ spacing⌋ + 1) × rows; lineal feet = pieces × length of each piece.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Pieces per row = ⌊ Run ÷ spacing ⌋ + 1
Total pieces = pieces per row × rows
Lineal feet = total pieces × length of each piece
Run the calculation to see each step with your own numbers.
A 40 ft wall, studs 16 in o.c., 9 ft long, 5% waste.
Pieces = ⌊480 in ÷ 16⌋ + 1 = 31
Lineal feet = 31 × 9 = 279 ft
+5%: order 33 studs
- Standard layout: members every spacing plus one to close the end. Openings, corners and partition intersections add extra pieces this doesn't count.
- All members the same length — enter separate runs for gable-end studs or stepped joists.
- Plates, headers, blocking and hangers are separate.
- Does this count corner studs and openings?
- No — it's the field member count. Add 2–3 studs per corner and per wall intersection, and account for king/jack studs and cripples at each opening — or use the Framing Calculator, which does.
- What is the 'rows / runs' field for?
- It multiplies identical runs in one go — enter 2 for a double top plate along the same wall, or the number of identical stud walls in the job.
- How many pieces of lumber for a 40 ft run at 24 inches on center?
- 21: 480 in ÷ 24 in = 20, plus one to close the end, or 23 with the default 5% waste. At 8 ft each, that is 168 lineal ft before waste.
- How do I convert a piece count to lineal feet?
- Multiply the number of pieces by the length of each one. 31 studs of 9 ft are 279 lineal ft; the calculator does this for every row you enter.
About the Lumber Calculator
The Lumber Calculator gives the piece count and total lineal feet for a repetitive run of framing members — studs, joists, rafters or blocking — at a set on-centre spacing, using the standard 'one per spacing plus one to close the end' layout. It counts the field members only; corners, partition intersections and the framing around openings add pieces it doesn't include. For a full wall take-off with those extras, use the Framing Calculator.
What you enter
- Run to cover — The length of wall / floor the members span across.
- On-centre spacing
- Length of each piece — Stud/joist/rafter length.
- Rows / runs — e.g. 2 for a double top plate along the same wall, or the number of identical walls.
- Waste allowance — Default 5%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Pieces — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Total lineal feet — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Framing Calculator — Stud count and lineal feet for a wall at a given stud spacing.
- Board Foot Calculator — Board feet for a piece or a list of lumber from its dimensions.
- Floor Joist Calculator — Floor joist count and a span estimate — an estimate, not an engineering design.
- Decking Calculator — Decking boards, joists and fasteners for a deck of a given size.
Part of the Lumber & Wood calculators.