Decking Calculator
Use this decking calculator to estimate how many boards you need for a new deck or a resurfacing job. Enter the deck size, board dimensions, waste allowance, and a board price to get a practical shopping estimate.
Result
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What This Decking Calculator Helps You Do
Use this decking calculator to estimate how many boards you need for a new deck or a resurfacing job. Enter the deck size, board dimensions, waste allowance, and a board price to get a practical shopping estimate.
How to Calculate Decking Calculator
- Measure the deck footprint - Enter the deck length and width in feet. If the shape is not a simple rectangle, split it into sections and add the areas.
- Enter board dimensions - Use the visible board width and the board length so the calculator can estimate the coverage area per board.
- Add waste and price - Waste helps cover cuts, damaged boards, and layout adjustments. Add a price per board for a rough budget.
- Order the result - Use the waste-adjusted board count when you place the order. The base count is the theoretical minimum.
Decking Calculator Formula
| Symbol | Definition | Unit |
|---|---|---|
| Length | Deck length | ft |
| Width | Deck width | ft |
| Board width | Visible width of one decking board | ft |
| Board length | Length of one decking board | ft |
| Waste | Extra allowance for cuts and mistakes | % |
Worked Examples
- Length: 12 ft
- Width: 16 ft
- Board width: 0.5 ft
- Board length: 8 ft
- Waste: 10%
Result: Base count = 48 boards. Order boards with waste = 52.8 boards.
The deck needs 48 boards before waste and about 52.8 boards after a 10% allowance.
- Length: 10 ft
- Width: 12 ft
- Board width: 0.5 ft
- Board length: 10 ft
- Waste: 8%
Result: Base count = 24 boards. Order boards with waste = 25.92 boards.
A long board length reduces the count, but you still need to add a little waste for cuts.
- Length: 14 ft
- Width: 18 ft
- Board width: 0.5 ft
- Board length: 12 ft
- Waste: 12%
Result: Base count = 42 boards. Order boards with waste = 47.04 boards.
The larger platform pushes the purchase quantity into the high-forty range once waste is added.
- Length: 20 ft
- Width: 10 ft
- Board width: 0.5 ft
- Board length: 8 ft
- Waste: 10%
Result: Base count = 50 boards. Order boards with waste = 55 boards.
The poolside deck needs a round fifty boards before waste and about fifty-five after the allowance.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| < 20 boards | Small deck | Check whether offcuts or a different board length can reduce waste. |
| 20-50 boards | Medium deck | Order a little extra so you can replace a damaged board later. |
| 50-100 boards | Large deck | Compare pack sizes and consider delivery timing before buying. |
| > 100 boards | Very large deck | Review the layout in sections and verify the board coverage assumptions. |
Frequently Asked Questions
Sources
Last reviewed: March 2026