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Decking & lumber

Deck material calculator

Estimate deck boards from clear dimensions, board direction, gaps, cuts and a chosen allowance. Review the method, a worked example and the limits before using your result.

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DECKING · MATERIAL PLANNER

Deck material calculator

Plan board rows, end cuts and a whole-board shopping estimate.

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Deck dimensions and results
m

Finished rectangular area. Range: 0.01–1000 m equivalent.

m

Exclude any perimeter clearance before entering dimensions.

Board & cutting settings

mm

Use actual width, not a nominal trade size. Range: 20–1000 mm equivalent.

mm

Editable example, not a product recommendation. Range: 0–25 mm equivalent; at most half the board width.

m

Length available after any end trimming. Range: 0.1–30 m equivalent.

Only identical end lengths are pooled. Ripped edge strips are never reused. Joints must be checked against supports.

mm

mm

Material lost between cuts. Editable example; range: 0–20 mm equivalent.

mm

mm

mm

%

Applied after the base cutting estimate. Editable example: 0–100%.

USD / m

Optional. Up to 1,000,000; no more than 2 decimal places.

Changing the label does not convert the price.

Enter decimals with a point or comma. Use spaces only for grouped thousands. Converted inputs are rounded for display; original quantities are retained.

DECK PLAN · TOP VIEW→
Full usable lengthEnd pieceRipped edge row

Illustrative rows and end joints. This is not an approved construction layout.

Scroll here for the cut list and buying options ↓

Your board estimate

Example values
Boards to buy—Whole stock boards
Board rows—Edge widths shown below
Base boards—Before extra allowance
Board cost · USD—Purchase quantity × board price
Clear deck area
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Each edge row width
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Cost per m²
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Length per row
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Installed row length
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Extra boards
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Purchased stock length
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Cut list · finished installed pieces

Finished pieces, excluding spare boards; grouped by length and width
LengthWidthQtyPurpose

Buying options

    Compare stock lengths

    Rectangular, straight parallel rows only. End-joint and perimeter gaps are included. Joints are shown without staggering or support validation. Follow the product’s gap and support requirements. No framing, fasteners, fascia, stairs, labour, delivery or taxes are included.

    Edits are saved in this tab when browser storage is available.

    How to use

    1. Enter the rectangular deck size and any perimeter clearance. Choose the direction in which the boards run.
    2. Enter actual board width, stock length and end trimming. Set side gaps, end gaps, saw kerf and the minimum permitted piece length for your plan.
    3. Compare separate-row cutting with reuse of equal end pieces. Enter a reserve and an optional price per board or unit length.
    4. Inspect the drawing, edge-row widths, base board count and final purchase count before checking the support and fixing plan.

    Calculation method

    Clear dimensions subtract perimeter clearance from both edges. The row count is rounded up from (across width + side gap) / (board width + side gap); the outer rows are ripped symmetrically. Runs are divided into usable stock lengths with the entered end gaps. Reuse pools matching end pieces and accounts for kerf, while separate mode keeps rows independent. A selected minimum piece can trigger two balanced end pieces. The allowance applies to the resulting whole base boards, then purchase rounds up again. Cost uses the complete bought boards or their stock length.

    Worked example

    A 3 m run across a 1.4 m deck, with 140 mm boards, zero gaps, no trimming and 3 m stock, uses 10 rows and 10 boards before reserve. A 10% reserve makes 11 boards. At 18 USD per board the purchase costs 198 USD. This simple example has no end pieces to pool; introducing a gap or changing the run can change the cut arrangement.

    Assumptions and limits

    This is a rectangular board estimate with restricted offcut reuse, not a general cutting optimizer. Ripped edge strips are not reused. Joist positions, fastening, structural spans, permitted rip widths, seam staggering and product movement requirements are not designed. Use dimensions consistent with the installation specification; a geometrically possible cut is not automatically supported.

    Continue your plan

    Compare material volume with the lumber calculator and check irregular measurements with the area calculator. For a separate boundary project, use the fence calculator.

    Copy, download or print a valid result to keep the inputs with the estimate. Currency selections label your prices; they do not apply an exchange rate. Product-dependent examples should be replaced with data for the material or equipment you actually use.

    For the measurement and planning details, read planning deck boards, gaps and reusable offcuts.