Trade & Construction
Estimate deck board count, running metres, waste allowance and optional material cost from deck size, board width, spacing and board length.
Trade & Construction
Module width = board width + gap. Board rows = ceiling(deck width ÷ module width). Running metres = board rows × deck length. Running metres with waste = running metres × (1 + waste percent ÷ 100). Stock boards = ceiling(running metres with waste ÷ stock board length). Optional material cost = stock boards × price per board.
This is the method behind the answer, so the result can be checked rather than simply trusted.What-if check
Board orders are sensitive to waste, stock length and gaps. Check these rows before treating the result as a purchase list.
| Waste | Linear metres | Stock boards |
|---|---|---|
| 0.0% | 135.0 m | 29 |
| 5.0% | 141.8 m | 30 |
| 10.0% | 148.5 m | 31 |
| 15.0% | 155.3 m | 33 |
| Gap | Rows | Boards |
|---|---|---|
| 3.0 mm | 26 | 33 |
| 5.0 mm | 25 | 31 |
| 7.0 mm | 25 | 31 |
Visual proof
The sketch shows why decking is a linear-material estimate: repeated rows across the width multiplied by the board run length.
Visual grid
Length, area, volume and material estimates are grid problems too: measure the space, account for edges and allowances, then turn the pattern into a number you can use.
Space calculations turn a real surface, room, run or volume into cells, edges and allowances that can be quoted, ordered or checked.
CalculationTime
Module width = board width + gap. Board rows = ceiling(deck width ÷ module width). Running metres = board rows × deck length. Running metres with waste = running metres × (1 + waste percent ÷ 100). Stock boards = ceiling(running metres with waste ÷ stock board length). Optional material cost = stock boards × price per board.
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Module width = board width + gap. Board rows = ceiling(deck width ÷ module width). Running metres = board rows × deck length. Running metres with waste = running metres × (1 + waste percent ÷ 100). Stock boards = ceiling(running metres with waste ÷ stock board length). Optional material cost = stock boards × price per board.
Deck width 3.6 m is 3,600 mm. A 140 mm board plus 5 mm gap gives a 145 mm module. Rows = ceiling(3,600 ÷ 145) = 25. Running metres = 25 × 5.4 = 135 m. Add 10% waste: 148.5 m. With 4.8 m stock boards: ceiling(148.5 ÷ 4.8) = 31 boards.
Master’s Tip: decide board direction and join pattern before ordering. A total-running-metre estimate is good for an early quote, but picture-frame borders, breaker boards, diagonal layouts and short offcuts can change the purchase count.
Standard or basis: transparent metric decking quantity arithmetic using board face width, spacing, stock board length and upward rounding. No structural design, span-table approval, timber durability class, slip rating or building-code compliance is claimed.
Methodology & Accuracy
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Module width = board width + gap. Board rows = ceiling(deck width ÷ module width). Running metres = board rows × deck length. Running metres with waste = running metres × (1 + waste percent ÷ 100). Stock boards = ceiling(running metres with waste ÷ stock board length). Optional material cost = stock boards × price per board.
Standard or basis: transparent metric decking quantity arithmetic using board face width, spacing, stock board length and upward rounding. No structural design, span-table approval, timber durability class, slip rating or building-code compliance is claimed.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master’s Tip: decide board direction and join pattern before ordering. A total-running-metre estimate is good for an early quote, but picture-frame borders, breaker boards, diagonal layouts and short offcuts can change the purchase count.
Divide the deck width by the board-plus-gap module to estimate rows, multiply rows by deck length to get running metres, add waste, then divide by the stock board length and round up.
Yes for row spacing. The calculator adds the entered gap to the board width so the row count reflects the repeated board module.
A simple straight deck may use about 5–10% as a planning allowance. Diagonal boards, picture-frame borders, poor stock, many joins or spare boards can need more.
No. It estimates surface boards only. Joist spans, posts, footings, fixings, railing and local code compliance must be designed separately.
The calculator rounds by total running metres. Real cut plans depend on stock lengths, staggered joins, defects, end trimming, board direction and whether offcuts can be reused.
Deck-board estimating combines area thinking with linear stock purchasing. The deck is a surface, but boards are bought as lengths, so a useful calculator must show rows, running metres, waste and stock-board rounding separately.
A deck has a square-metre footprint, but most decking boards are purchased as linear pieces. That is why this calculator starts with repeated board rows and running metres instead of stopping at deck area.
The gap between boards affects how many rows fit across the deck. Real spacing also depends on timber movement, moisture, composite-board instructions and local installation guidance, so the gap remains an editable input rather than a fixed rule.
Straight full-length boards can be efficient. Diagonal layouts, breaker boards, picture frames, stairs, posts and staggered joins create more cuts and can require extra stock even when the measured area is unchanged.
Total running metres are useful for early pricing, but a final order should be checked against actual stock lengths and a marked cutting plan. Recording the assumptions makes that next step easier.
