Fence Calculator
By Taro Schenker | Updated February 11, 2026
Quick Answer: To calculate fence materials, divide your total fence length by post spacing (typically 8 ft) and add 1 to get post count, plus 2 extra posts per gate. Rails = sections x rails per section (2 or 3). Pickets per section = section width in inches / picket width. For privacy fences, use 5.5-inch boards with no gap; for picket fences, 3.5-inch boards with 1.75-inch gaps. Each post needs about 0.33 bags of 80 lb concrete. Add 10% for waste. A 100-foot privacy fence at 8-foot spacing needs 14 posts, 26 rails, and approximately 218 pickets.
Calculate how much fencing material you need for your project. Enter your fence length, height, and post spacing to get the exact number of posts, pickets or boards, rails, and concrete bags. Choose from privacy, picket, chain-link, or vinyl fence types and get an instant cost estimate.
How to Calculate Fence Materials
The basic formulas for calculating fence materials:
- Measure the total linear length of your fence line in feet.
- Subtract the width of any gates from the total length.
- Divide the fence length by your post spacing (typically 8 feet) and add 1 to get the number of posts.
- Multiply the number of sections by your rail count (2 or 3) to get the total rails needed.
- Calculate pickets per section based on board width and gap, then multiply by the number of sections.
- Add 10% for waste from cuts and damaged materials.
Fence Type Comparison
Compare the cost, lifespan, and maintenance requirements of common fence types:
| Type | Cost / Linear Ft | Lifespan | Maintenance |
|---|---|---|---|
| Wood Privacy | $15 - $35 | 15 - 20 years | Stain/seal every 2-3 years |
| Picket | $10 - $25 | 15 - 20 years | Paint/stain every 2-3 years |
| Chain Link | $8 - $18 | 20 - 30 years | Minimal; check for rust |
| Vinyl | $20 - $40 | 25 - 30+ years | Occasional wash; virtually none |
Post Spacing Guide
- 6-foot spacing: Best for areas with high winds, heavy snow loads, or when using heavier boards. Provides maximum strength and rigidity.
- 8-foot spacing: The most common spacing for residential wood fences. Standard lumber and rails come in 8-foot lengths, minimizing waste and cuts.
- 10-foot spacing: Typical for chain-link fences and some ranch-style fences. Not recommended for privacy fences as it can cause sagging.
- Corner and gate posts: Always place posts at corners, direction changes, and on both sides of gates. These posts should be set deeper and with extra concrete.
Formula Summary
Post Count Formula: Calculate the number of fence posts by dividing the fence length by post spacing, adding 1, plus 2 extra posts per gate.
$$\text{Posts} = \lfloor \frac{L_{\text{fence}}}{S_{\text{post}}} \rfloor + 1 + N_{\text{gates}} \times 2$$
Rails Formula: $$\text{Rails} = (\text{Posts} - 1 - N_{\text{gates}}) \times R_{\text{per section}}$$
Pickets Formula: $$\text{Pickets} = \lceil \frac{S_{\text{post}} \times 12}{W_{\text{picket}} + G} \rceil \times \text{Sections} \times (1 + W\%)$$
where $G$ = gap width (0 for privacy fences, typically 1.75" for picket fences) and $W\%$ = waste factor.
| Constant | Value |
|---|---|
| Chain-link roll length | 50 ft |
| Concrete per post | 0.33 bags (80 lb) |
| Privacy picket width | 5.5 in (no gap) |
| Picket fence board width | 3.5 in + 1.75 in gap |
| Standard post spacing | 8 ft |
Standard Assumptions: Waste factor of 10% accounts for cuts and damaged materials. Rails per section is 2 or 3 depending on fence height. Chain-link uses 2 rails per section (top rail + bottom tension wire). Chain-link fabric roll cost is approximately $75 per 50 ft roll.
Related Calculators
- Concrete Calculator — calculate concrete for post holes, footings, and slabs
- Deck Board Calculator — estimate lumber for deck building projects
- Board Foot Calculator — convert lumber dimensions to board feet for pricing
Estimates are for planning purposes only. Consult a qualified contractor for critical projects. Actual material requirements may vary based on site conditions, waste, and installation methods.
Pricing last verified: February 2026. Material prices vary by region, season, and supplier. Prices shown are national averages for planning purposes.