Lumber Calculator
Work out how many boards you need for a run, plus linear feet, board feet and total cost.
What you need
14
Boards to buy — Rounded up, waste allowance included.
- Total linear feet purchased
- 112.0 ft
- Leftover material
- 16.0 ft
- Board feet purchased
- 49.0
What you will have spare after cutting. Useful for blocking and jigs.
Estimates for planning. Confirm quantities with your supplier before ordering — see the assumptions below for the figures used.
How to use the lumber calculator
When you know the total length of material a job needs, the question becomes how many stock-length boards to buy — and how much you waste in offcuts. Enter your total run and the lengths on the shelf.
What this calculator assumes
Every estimate depends on figures that vary by supplier and conditions. These are the ones used here, so you can sanity-check the result against your own quote.
- Board count assumes you can cut freely from stock lengths. If every piece must be a single uncut run — for example a 10 ft rail — buy one board per piece instead, at that length.
- Board feet use actual dressed dimensions: a 2x4 is 1.5 × 3.5 in, a 2x6 is 1.5 × 5.5 in, and so on.
- Leftover material assumes perfect cutting with no kerf loss. Each cut removes about 1/8 in.
- Pressure-treated lumber is heavier and often wetter than kiln-dried; expect some movement as it dries.
Frequently asked questions
What is a linear foot?
Just length — one foot of board, whatever its width or thickness. If you need 12 pieces at 8 feet each, that is 96 linear feet. It is the right unit for trim, railings and framing runs.
Why is a 2x4 not actually 2 by 4 inches?
Nominal sizes refer to the rough green dimensions before drying and surfacing. A finished 2x4 measures 1½ by 3½ inches. It matters when you are calculating wall thickness, notching, or fitting anything into a cavity.
How do I minimise lumber waste?
Match stock length to your cut list. Twelve 4-foot pieces come out of four 12-foot boards with zero waste, but six 8-foot boards leave you six 4-foot offcuts. Work out your cut list first, then choose the length that divides into it cleanly.
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