Inputs
Affects row count, joists, and length.
Measured from deck length axis. Range 5–85°.
Used for single best and mixed optimizer.
Adds perimeter boards around the deck edges.
Covers miters, returns, and trimming.
Results
Deck area
— m²
Rows of boards
—
Total board length
— m
includes waste and borders
Border length added
— m
Chosen stock length
— m
Boards needed: —
Linear waste: — m
Joists required
—
Fasteners needed
—
Cost summary
| Item | Qty / Length | Unit | Unit price | Subtotal |
|---|---|---|---|---|
| Run the calculator to see costs. | ||||
| Total | — | |||
Formula used
- Coverage per course
C= board width + gap. - For straight layouts: rows
N= ceil(perpendicular deck span ÷C). - For diagonal angle
φ: parallel spanP = L·cosφ + W·sinφ, perpendicular spanQ = L·sinφ + W·cosφ, rowsN = ceil(Q ÷ C). - Linear length before borders and waste
L₀=P × N(orrun × Nfor straight). - Picture-frame borders: perimeter
U = 2(L + W); addk·U·(1+β)wherekis 0/1/2 andβis border allowance. - Total linear meters with waste
L=(L₀ + L_border) × (1 + waste%)(unless unticked for borders). - Single-length boards: choose
S*minimizingceil(L/S)·S − L. - Mixed-length optimizer: find integer counts to reach ≥
Lwith minimal overfill using dynamic programming on 0.1 m steps. - Joists: count along board direction:
J = floor(P ÷ spacing) + 1; each joist length is the perpendicular span. - Fasteners: intersections × pieces per intersection (2 for screws, 1 for clips).
How to use this calculator
- Select unit system and board orientation, then set angle for diagonal.
- Enter deck length and width, board width, and desired gap.
- Choose stock lengths and Length strategy: single or mixed.
- Use picture-frame controls to add single or double borders.
- Set waste, joist spacing, fastener type, and pricing fields.
- Click Calculate, then export results as CSV or PDF.
Example data table
| # | Units | Deck L | Deck W | Board W | Gap | Orientation | Angle | Stock lengths | Strategy | Borders | Waste % | Joist spacing | Load |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Metric | 6.0 m | 4.0 m | 140 mm | 5 mm | Diagonal | 45° | 3.0, 3.6, 4.8 | Mixed | Single (10%) | 8 | 400 mm | |
| 2 | Imperial | 20 ft | 12 ft | 5.5 in | 0.19 in | Along width | — | 8, 10, 12, 16 | Single | Double (12%) | 10 | 16 in |
Click Load to populate inputs, then press Calculate.
Frequently asked questions
The tool computes rows from coverage and spans, adds optional borders, applies waste, and then chooses stock counts by strategy. Real projects may add offcuts at seams, borders, or picture frames.
Yes. Select the mixed-length optimizer to minimize overfill using dynamic programming on 0.1 m steps. This produces a near‑optimal combination of boards for your total length.
Common choices are 30°, 45°, or 60°. Larger angles increase the number of courses. Always confirm allowable joist spacing for diagonal installation with your board manufacturer.
Single adds one perimeter course; double adds two. We include a user‑set allowance for miters and returns. General waste may also apply if the checkbox is enabled.
We multiply board rows by joists to get intersections, then 2 pieces per intersection for screws or 1 for clips. Perimeter borders typically fasten to rim joists and blocking and are not separately counted here.
Yes. It estimates joist count and total length from orientation and spacing, then multiplies by a per‑meter rate for a quick budgetary figure.
Always verify spans and connections with manufacturer literature and your local code authority.