Picket fence calculator

Get the gap and bay layout right

A narrower gap uses more pickets. This tool rounds up each bay separately, so you can trim the final picket or adjust the end gaps when laying out a bay. Use the waste allowance to reserve extra boards for cuts or damaged pieces.

Subtract the openings, then plan the gates separately

Total length includes the gate openings. The calculator removes those openings from the picket and rail runs and adds posts at the gate boundaries. Gate infill, hinges, latches and bracing need their own list. Corners share posts between adjoining sides. If several gates share posts, draw that layout before ordering.

Measure board width, gap and the fence route

Measure the face of the picket you intend to buy. Enter that actual width, then enter the clear gap you want between adjacent boards. The gap is measured edge to edge, not center to center. Dry-fit the layout on the proposed bay before fastening boards, because the end spaces and any trimmed picket need to look right at the posts.

Draw each side and mark openings. Measure the whole side including its gates; the calculator subtracts those openings. Choose maximum post spacing that matches the fence design. Shortening that spacing can change the picket total because each bay is rounded separately. A count based only on total footage misses that rounding at the posts.

Worked example: an open picket fence

Use an illustrative 100 ft straight run at 4 ft high, with no gates and 8 ft maximum post spacing. Choose 3.5 in actual board width and a 3.5 in clear gap for this calculation; these are example inputs, not a required product layout. The tool returns 13 equal bays and 14 posts.

Each bay is about 92.31 in long. Adding the gap to that length, then dividing by board width plus gap, gives 13.69 boards before rounding. Round up to 14 per bay, for 201 pickets along the run. The model also returns 29 rail pieces using its rail-row assumption. Rail pieces are not a purchase list until their lengths and connections are checked.

Dimension references: actual picket width and Lowe's spacer example. The spacer guide describes shadowbox construction; this example counts only a single face. The chosen gap is not a code limit or a guarantee of containment.

Why the formula adds a gap before dividing

A row of boards has a gap between neighboring boards, but no extra gap after the final board. Adding a gap to the bay length accounts for that missing last gap when calculating coverage. The tool rounds up to avoid an undercount. A rounded result may require a trimmed end picket or adjusted spacing, so it is not an instruction to fasten full-width boards at exactly the entered gap without laying them out first.

Common counting mistakes

• Entering a nominal lumber size instead of measuring the board face.
• Subtracting a gate by hand, then entering that gate and subtracting it again.
• Dividing the full fence length by board coverage and ignoring separate bays.
• Buying the exact result without checking cuts, damaged boards or the seller's return policy.
• Using the fence-run pickets to cover a gate whose frame and bracing need a separate layout.

Privacy, overlap and horizontal boards

A no-gap, side-by-side wood fence uses board face width as coverage. A board-on-board fence overlaps boards, so face width alone overstates the area each board covers. Calculate that layout from its overlap detail instead of using a negative gap. Horizontal boards need their own support spacing, stock-length and cut plan; this tool counts vertical pickets.

If boards vary in width or you want a symmetrical pattern around the middle of each bay, mark out a trial bay before ordering the final count. The calculator does not reserve an allowance for a decorative pattern, curved top or an overlapping gate face.

Use the board count separately from the cost range

The quantity result describes the open picket layout you entered. The wood cost rate used by this site's main estimator is for privacy fencing, so changing picket width or gap does not produce a matching open-picket price. Take the board, rail and post list to a supplier for a product-specific price, including fasteners and gate parts. Do not infer a picket unit price by dividing a broad privacy budget by this count.