Outdoor Build
Deck and Fence Material Calculator
Turn deck or fence dimensions into board counts, post counts, joists, and fastener quantities.
Your deck
Deck and fence builds share the same logic
Both projects reduce to the same three questions: how much structural framing (joists or posts and rails) do you need to hold everything up, how much surface material (decking boards or pickets) covers the visible face, and how many fasteners and footings tie it all together. Getting the framing spacing right early avoids expensive rework later — decking that bounces or a fence panel that sags almost always traces back to framing spaced too far apart.
Deck framing basics
| Decking material | Joist spacing (perpendicular) | Joist spacing (diagonal/45°) |
|---|---|---|
| Wood (5/4 or 2x lumber) | 16 in on-center | 12 in on-center |
| Composite decking | 16 in on-center (check span table) | 12 in on-center |
| PVC decking | 12-16 in on-center | 12 in on-center |
Fence framing basics
| Fence type | Post spacing | Rails per section |
|---|---|---|
| Standard picket fence (under 5 ft) | 8 ft | 2 |
| Privacy fence, 6 ft tall | 8 ft (6 ft in high wind areas) | 3 |
| Solid panel / board-on-board | 6-8 ft | 3 |
Post footing depth guide
| Fence height | Minimum burial depth | Concrete per hole |
|---|---|---|
| Up to 4 ft | 18-24 in | 1-1.5 bags (50 lb) |
| 5-6 ft | 24-30 in (or to frost line) | 2 bags (50 lb) |
| 7 ft+ | 30-36 in (or to frost line) | 2-3 bags (50 lb) |
Ordering checklist
- Measure the actual run or footprint on site, not just from a plan — decks and fences rarely follow perfectly straight property lines.
- Calculate framing (joists, posts, rails) before surface material, since surface material quantities depend on framing layout.
- Add 10% waste for straight cuts, 15% for diagonal decking or fences on sloped or curved ground.
- Order concrete, fasteners, and hardware together — running short mid-project on a Sunday is the most common build delay.
- Check local permit and setback requirements before setting the first post; many municipalities require a permit for fences over a certain height.
How far apart should deck joists be spaced?
16 inches on-center is standard for most decking boards run perpendicular to the joists. Composite decking and boards laid diagonally often require tighter 12-inch spacing — check your decking manufacturer's span table.
How deep should fence posts be set in concrete?
A common rule is one-third of the post's above-ground height, with a minimum of 24 inches in frost-free climates and below the frost line where the ground freezes. A 6-foot fence typically needs posts set at least 2 feet deep.
How much waste should I allow for decking and fencing lumber?
Add 10% for straightforward rectangular layouts, and 15% for boards run diagonally, curved layouts, or fences following uneven terrain that requires extra cutting.
Can I use the same post spacing for every fence style?
No. Standard picket and privacy fences commonly use 8-foot post spacing, but taller or solid privacy panels facing high wind loads often need posts every 6 feet for adequate strength.
Last reviewed February 2026