How the fence calculator works
- Sections = fence length ÷ post spacing, rounded up.
- Posts = sections + 1 (for a straight run).
- Rails = 2 per section on fences up to 5 ft tall, 3 per section on taller fences.
- Boards = length in inches ÷ (board width + gap).
- Concrete = hole volume minus the post, divided by the 0.375 cu ft a 50 lb bag of fast-setting mix yields.
Actual lumber sizes
Lumber is sold by nominal size, which is larger than the real board. Use the actual width in the calculator.
| Nominal | Actual |
|---|---|
| 1 × 4 | 3/4" × 3 1/2" |
| 1 × 6 | 3/4" × 5 1/2" |
| 2 × 4 (rail) | 1 1/2" × 3 1/2" |
| 4 × 4 (post) | 3 1/2" × 3 1/2" |
| 6 × 6 (post) | 5 1/2" × 5 1/2" |
Before you dig
- Call 811 a few days before digging. It is free and marks buried gas, power and water lines.
- Check your property line, HOA rules and local height limits (often 6 ft in back yards and 3–4 ft in front).
- Use ground-contact rated pressure-treated posts.
- Set corner and end posts first, then run a string line to align the posts in between.
