Fence Calculator
Estimate panels, feather edge boards or vertical slats, with posts, rails and optional material costs.
Your fence estimate
Enter your fence measurements, then calculate.
Materials to buy
Check the panel cut widths before buying. Very narrow sections may need a different layout or extra framing. Confirm that your supplier permits cutting and follow their instructions for supporting and treating cut edges.
Other materials to check
- Suitable nails, screws, panel clips or rail brackets for your fixing system.
- Post caps, capping and counter rails if required by your chosen design.
- Cut-end preservative where required by the timber supplier.
- Post-setting concrete, calculated separately using your post count and hole dimensions.
Use the Postcrete calculator for post-hole concrete and bag quantities. These items are not included in this material subtotal.
Calculation and assumptions
Quantity estimate for a straight, level run with new posts at both ends. Choose suitable material heights and post lengths separately. No gates, corners, existing posts, concrete, capping, fixings, delivery or labour are included. Full-height vertical boards are assumed; offcuts are not reused. Each rail and gravel board is bought as one piece per bay, without stock-length optimisation. Confirm fitting, trimming, heights and structural suitability with the supplier. Panel cuts must allow for the chosen product’s frame, fixings and minimum usable width; a calculated cut width does not confirm that a panel can be safely trimmed.
Use this fence calculator to work out how many panels, posts or individual boards you need for a straight garden fence. Choose ready-made panels, feather edge boards or vertical slats, with optional gravel boards and material costs using your supplier’s prices.
PRO TIP: Check the smallest panel cut before ordering. A narrow strip may lose the frame or fixing points it needs; ask your supplier about a revised layout or a suitable cut-down kit before installing posts.
How to use this fence calculator
- Measure the straight run from the outside face of the first post to the outside face of the last. Leave out gate openings. Metric mode uses metres and millimetres; Imperial uses decimal feet and inches for the corresponding fields.
- For ready-made panels, enter the actual supplied width and choose between-post or slotted fitting. For slotted posts, use the actual insertion at each end after fitting clearances, rather than the full slot depth.
- For individual boards, enter the board width, overlap or maximum gap, and your supplier’s maximum post-centre spacing. Choose the specified rail count and adjust the extra-board allowance if needed.
- Include gravel boards if required. Finished height includes their height: a 1.8 m fence with a 150 mm gravel board leaves 1.65 m for the panel or boards, with no separate ground gap.
- Use Advanced to match rail fitting, gravel-board insertion and an optional below-ground post length to your installation. These settings remain active when you return to Standard. Enter unit prices only for materials you want costed.
Understanding your results
Use the panels or boards “to buy” figure when ordering. The individual-board total already includes your chosen spare allowance; the panel count has no extra-panel allowance.
Check the layout and cut lengths before setting out posts. Panels normally use full widths followed by a final cut; where that would leave no usable final opening, cuts are shared equally across the bays. A calculated width does not confirm that your chosen panel can be trimmed to it.
Rail and gravel-board schedules show finished pieces, with one stock piece allowed for each listed cut. Offcuts are not reused and saw-cut or trimming allowances are not added. Choose stock lengths and prices that suit those cuts. Slat gaps may be smaller than the maximum entered.
The cost is a material subtotal for the prices entered. Blank prices are excluded, so a partial subtotal is not the cost of all materials. Fixings, concrete, capping, delivery and labour are excluded.
If you’re setting posts in Postcrete, use our Postcrete calculator to estimate bags from your post count, post dimensions and specified hole size.
How the maths works
Panels: bays = (run length − one post thickness) ÷ (panel width − twice the insertion per end + post thickness), rounded up. Between-post fitting uses zero insertion. Posts = bays + 1; gravel boards = one per bay when selected.
Example: a 10 m run with 1.83 m panels, 100 mm posts and between-post fitting needs 6 panels and 7 posts. Five panels remain 1.83 m wide; the final panel is 0.15 m wide. That narrow section needs supplier review before installation.
Individual boards: the distance between the end-post centres is divided into equal bays within your chosen maximum spacing. Boards cover the end posts, and each bay is counted separately. Feather edge uses (clad width − overlap) ÷ (board width − overlap), rounded up; vertical slats use (clad width + maximum gap) ÷ (board width + maximum gap), rounded up. The total is increased by the spare percentage and rounded up to whole boards.
Common mistakes to avoid
- Treating 1.8 m and 1.83 m panels as interchangeable. Use the actual supplied width; post thickness and slot engagement also affect the run.
- Using a rail count as a shopping count for long stock lengths. The result counts separate rail pieces per bay, without working out how many cuts could come from a longer rail.
faqs
Can I use this for corners, gates or an existing fence?
Calculate each straight run separately, then reconcile shared corner posts so they are not counted twice. The tool assumes new posts at both ends; existing posts and gate posts need a separate layout check. For replacement panels, measure the existing openings and slot engagement directly.
How deep should my fence posts go?
The calculator does not select a safe post depth. Use the specification for your fence system and site conditions. If you enter a below-ground length in Advanced, it is added to the finished height to estimate the minimum total post length; check the available stock size with your supplier.
Does this calculate horizontal or double-sided slatted fencing?
No. Slatted mode assumes one layer of upright boards fixed to horizontal rails. Horizontal boards, hit-and-miss and double-sided designs need a different quantity calculation.
disclaimer
This is a material estimate for a straight, level run, not a structural design or installation plan. Sloping ground, wind exposure and the chosen fence system may change the specification. Check supplier requirements and buried services before digging. The preview is schematic, not a setting-out drawing.