Feather Edge Board Calculator: How Many You Need

A feather edge board calculator works out how many feather edge (overlap) fence boards you need for a given fence run, based on the board width, the overlap between boards, and the total length of the fence. You enter the fence length, board width, and overlap (or board coverage), and it returns the number of boards required, rounded up to whole boards. It also shows the total linear metres of boards and the effective coverage per board, so you can order the right quantity without overbuying.

Formula

The calculator uses the standard overlap fencing formula:

Number of boards = ceil( Fence length × 12 / (Board width − Overlap) )

Where:

• Fence length (ft) – the total horizontal run of the fence you are covering.
• Board width (in) – the actual width of one feather edge board, typically 4–8 inches.
• Overlap (in) – the amount each board overlaps the previous one, usually 1–2 inches.
• Ceil() – rounds up to the next whole number because you cannot buy a fraction of a board.

The effective coverage per board is (Board width − Overlap) in inches. For example, a 6-inch board with a 1-inch overlap covers 5 inches of fence length.

Worked Example

Using the default values from the calculator above:

• Fence length = 60 ft
• Board width = 6 in
• Overlap = 1 in

Step 1: Convert fence length to inches: 60 ft × 12 = 720 in.

Step 2: Calculate effective coverage: 6 in − 1 in = 5 in per board.

Step 3: Divide total inches by coverage: 720 ÷ 5 = 144 boards.

Step 4: Round up: 144 is already whole, so you need 144 boards.

Total board length (if you were to lay them end-to-end) = 144 × 6 in = 864 in = 72 ft. This is more than the fence length because of the overlap.

Why Feather Edge Boards Overlap

Feather edge (also called overlap or lapped) fencing uses boards that are thicker on one edge and taper to a thin edge. The thick edge of one board overlaps the thin edge of the next, creating a weatherproof barrier that sheds rain and hides gaps as the wood shrinks. The overlap is essential – it prevents gaps from opening up between boards as the timber dries and warps. Without overlap, you would see daylight through the fence and lose privacy.

Typical overlaps range from 1 to 2 inches. A larger overlap gives a stronger, more private fence but uses more boards. A smaller overlap is more economical but may leave gaps if the boards shrink. The calculator lets you adjust the overlap to see how it affects the board count.

How to Choose Board Width and Overlap

Your choice of board width and overlap depends on the look you want, your budget, and the level of privacy you need.

• Board width: Common widths are 4, 5, 6, and 8 inches. Wider boards cover more length per board, so you need fewer boards, but they can be more prone to warping and are heavier to handle.
• Overlap: For a standard garden fence, 1 inch is typical. If you want maximum privacy and strength, use 1.5 or 2 inches. For a temporary or low-cost fence, 0.5 inch might be acceptable, but it is not recommended for permanent fencing.
• Board length: Feather edge boards come in lengths such as 4, 5, 6, or 8 feet. The length of the board determines the height of the fence. This calculator assumes the boards are long enough to cover the full height; if you need to join boards vertically, you will need additional boards and a horizontal rail to support the joint.

Always buy a few extra boards (typically 5–10%) to allow for cutting, damaged boards, and mistakes. The calculator gives the exact number for the run, but site conditions often require trimming.

Common Mistakes When Calculating

Even with a calculator, people make errors. Here are the most frequent ones:

• Mixing units: Fence length is often measured in feet, while board width and overlap are in inches. The calculator handles this, but if you are doing it by hand, convert everything to the same unit first.
• Forgetting the overlap: Some people simply divide the fence length by the board width, which undercounts boards because it ignores the overlap. This is the most common mistake.
• Not rounding up: You cannot buy 143.2 boards; you must buy 144. Always round up to the next whole number.
• Ignoring wastage: The calculator gives the theoretical number. In practice, you will cut boards at ends, and some boards may be defective. Add 5–10% extra.
• Assuming board width is coverage: The board width is the physical width, but the coverage is width minus overlap. For a 6-inch board with 1-inch overlap, coverage is 5 inches, not 6.

Cost Considerations

The calculator tells you the board count, but the total cost depends on the price per board, which varies by timber type, quality, and your location. Feather edge boards are commonly sold in packs or individually. To estimate cost, multiply the number of boards by the price per board, then add the cost of fence posts, rails, nails or screws, and concrete if needed.

Because the calculator rounds up to whole boards, you know the minimum number to buy. For a 60 ft fence with 6-inch boards and 1-inch overlap, you need 144 boards. If boards cost $2.50 each, that is $360 just for boards. Adding 10% for waste brings it to 158 boards, or $395.

Alternatives to Feather Edge Boards

Feather edge is not the only fencing option. Depending on your needs, you might consider:

• Closeboard fencing: Similar to feather edge but uses square-edged boards that butt together. It uses more timber and is heavier, but gives a flatter, more uniform look.
• Paling or picket fencing: Boards are spaced with gaps, using fewer boards and less timber. Good for boundaries where privacy is not essential.
• Panel fencing: Pre-made panels (e.g., 6×6 ft) are quicker to install but less flexible for uneven ground and can be more expensive per metre.
• Composite or vinyl boards: Low maintenance but higher upfront cost. The same overlap calculation applies, but board widths may differ.

Each alternative has different spacing rules, so the feather edge calculator only applies to overlap-style boards.

Frequently Asked Questions

How much overlap should I use?

For a standard feather edge fence, 1 inch of overlap is typical. Use 1.5 or 2 inches for extra privacy and strength, especially in windy areas. More overlap means more boards and higher cost.

Can I use this calculator for a fence that is not straight?

Yes, but you should measure the fence length along the line of the fence, not the straight-line distance between corners. If the fence curves or has steps, measure each straight section separately and add them together.

What if my board width is in millimetres?

Convert millimetres to inches by dividing by 25.4. For example, a 150 mm board is about 5.9 inches. The calculator expects inches, so convert before entering.

How many boards do I need for a 100 ft fence?

Using the defaults (6-inch board, 1-inch overlap): 100 ft × 12 = 1200 in; coverage = 5 in; 1200 ÷ 5 = 240 boards. Add 10% for waste = 264 boards.

Do I need to add extra boards for cutting at corners?

Yes. At corners, you may need to cut boards to fit, and you might need a wider board or a corner post arrangement. Adding 5–10% extra boards is a good practice.

What is the difference between feather edge and closeboard?

Feather edge boards are tapered and overlap, while closeboard uses square-edged boards that butt together. Closeboard uses more timber, is heavier, and gives a flatter appearance, but is usually more expensive.

Related

• Board Measurement Calculator: How to Use It
• Board Calculator for Walls: How to Estimate Lumber
• Board Calculator for Decking: How to Estimate

in fl | Fence length | ft | 60 | 0 | 100000
in bw | Board width | in | 6 | 1 | 24
in ov | Overlap | in | 1 | 0 | 12
out n | Boards needed | boards | ceil(round(fl * 12 / (bw - ov), 6)) | 0
out cov | Coverage per board | in | bw - ov | 2
out total | Total board length | ft | ceil(round(fl * 12 / (bw - ov), 6)) * bw / 12 | 1