Wood Fence Calculator
Estimate sections, posts, rails, pickets, post length, and concrete for a straight wood fence run.
Project inputs
Pickets
Post footing
Live estimate
Material schedule
| Item | Basis | Quantity | Unit |
|---|---|---|---|
| Posts | Sections + 1 | 13 | pieces |
| Rails | 2 per section | 24 | pieces |
| Pickets | Fence length ÷ module width | 159 | pieces |
| Total rail length | Rails × section length | 192.00 | ft |
| Concrete | Hole minus post, plus 10% | 0.93 | yd³ |
How to use this wood fence calculator
What this calculator does
This calculator turns the basic geometry of a straight wood fence into a material schedule. It estimates the number of sections, posts, rails, and pickets; recommends a post length equal to about 150% of the visible fence height; and estimates concrete by subtracting the embedded post volume from a cylindrical post hole. It is a quantity-planning tool, not a structural design, wind-load check, permit determination, or substitute for local frost-depth and utility-location requirements.
When to use it
Use it while comparing fence layouts, preparing a lumber takeoff, checking how a smaller picket gap changes the order quantity, or estimating the concrete needed before buying bagged mix. It is especially useful for a single straight run with evenly spaced posts. Treat corners, slopes, gates, stepped panels, and unusually exposed sites as separate design items.
How to calculate
- The calculator opens with a complete 96 ft demonstration fence, so the results and example Excel workbook are immediately available.
- Replace Fence length, Post spacing, and Fence height with your project dimensions. Use decimal feet, such as 7.5 ft.
- Enter Rails per section, Picket width, and Picket spacing. Picket dimensions use inches.
- Choose Post shape, then enter Post width / diameter, Post thickness when rectangular, Hole diameter, Hole depth, and Concrete waste allowance.
- Read the live result cards and material schedule. Select Download Excel to export the current validated model. Reset clears the demonstration and may disable export until every required field is complete again.
Input guide
Fence length is required, entered in feet, and must be greater than zero; 96 ft is the example. A longer run generally increases every material count. Post spacing is the maximum center-to-center spacing in feet; 8 ft is common for many panel layouts, but the correct value depends on the fence system and loads. Entering zero or spacing longer than the run is rejected. Fence height is the visible height in feet; the example is 6 ft. The displayed recommended post length adds approximately 50%, following the common one-third-buried planning rule, but actual embedment must account for local soil and frost conditions.
Rails per section is a required whole number from 1 to 10; the example uses 2. More rails increase the rail count and total rail length. Picket width and Picket spacing are required inches; the example uses 5.5 in boards with a 1.75 in gap. The calculator divides the full fence length by their combined module width and rounds upward. Use actual dressed width rather than a nominal lumber name, and do not confuse the gap with center-to-center spacing.
Post shape selects either square/rectangular or round geometry. Post width / diameter is required in inches; for a rectangular post, Post thickness is also required. The example uses an actual 3.5 × 3.5 in post. Hole diameter and Hole depth describe a cylindrical concrete hole in inches; the demonstration uses 12 in by 30 in. The hole must have more cross-sectional area than the embedded post. Concrete waste allowance accepts 0 – 50%; 10% accounts for irregular excavation and handling loss. For installation guidance, consult the American Wood Council's wood construction resources and local requirements.
Output guide
Number of sections is the fence length divided by maximum post spacing, rounded up. Number of posts is one more than the section count for an open straight run. Actual section length is the run divided evenly among those sections, so it will not exceed the requested spacing. Recommended post length is 1.5 times the fence height. Number of rails multiplies sections by rails per section, while Rail length total multiplies that count by actual section length.
Number of pickets is the primary whole-piece estimate. Concrete per post is the hole volume minus the embedded post volume, including waste, shown in cubic feet. Concrete volume is the total for all posts, shown in cubic yards. Zero is not meaningful for a completed fence; unusually high values usually indicate an oversized hole, deep embedment, or an input-unit mistake. The schedule repeats these quantities in purchasing units and is an estimate rather than a code recommendation.
Worked example
For the startup example, 96 ft divided by 8 ft gives exactly 12 sections, so the open run needs 13 posts. Two rails per section produces 24 rails, and 24 × 8 ft gives 192 ft of rail length. Each picket module is 5.5 + 1.75 = 7.25 in; the 1,152 in fence run divided by 7.25 is 158.90, which rounds up to 159 by pure spacing math. The result is therefore 159 pickets after rounding up to a whole board. A 12 in diameter, 30 in deep hole minus a 3.5 × 3.5 in embedded post, with 10% waste, requires about 1.93 ft³ per post, or 0.93 yd³ total for 13 posts.
Learn more
Before digging, review the U.S. Common Ground Alliance's 811 before-you-dig guidance. For wood durability, species, moisture, and fastener considerations, the USDA Forest Products Laboratory publishes the authoritative Wood Handbook. Concrete yield varies by product, so compare the cubic-volume result with the bag yield printed by the manufacturer.
Planning assumptions and common mistakes
The section formula intentionally rounds up so the actual bay length stays at or below the requested maximum. The post formula assumes a straight, open run; a closed perimeter typically reuses the first post at the end, while gates and corners may require additional or heavier posts. Picket count is sensitive to actual board width and gap. Wet lumber, board movement, privacy overlap, and alternating layouts can change the final count.
The concrete estimate assumes vertical cylindrical holes with no gravel displacement and uniform depth. Real holes are rarely perfect, so the waste allowance is useful, but it should not replace a site-specific footing design. Frost depth, wind exposure, soil bearing, drainage, post treatment, and gate loads can govern installation. Mark the layout in the field before purchasing and verify the final spacing against the chosen fence system.