Lumber Calculator
Lineal feet and piece count of dimensional lumber for a job.
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.
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.