Fence Calculator
Estimate fence posts, sections, rails, pickets or panels, concrete and optional material cost for a fence project.
Fence Dimensions
Gates and Corners
Rails and Fence Covering
Optional Material Prices
About the Fence Calculator
Planning a fence involves more than multiplying the total length by a single number. Posts need to be spaced along the run, rails connect the posts, pickets or panels cover the fence face, gates interrupt the fence line, and posts need suitable foundations. This Fence Calculator brings those quantities together so you can make a practical material estimate before shopping.
Enter the total fence length, finished fence height and centre-to-centre post spacing. The calculator subtracts gate openings from the fence line, divides the remaining run by the selected spacing and rounds up to ensure the complete run is covered. A straight run normally needs one more post than its number of sections because there is a post at each end. Gate and corner posts are then added separately.
Fence post formula
The basic calculation is sections = ceiling(fence line / post spacing). Fence line equals the total measured length minus the widths of the gate openings. Base posts for a straight run are sections + 1. Each gate adds two dedicated gate posts, and additional corner posts can be entered for changes of direction.
Rail calculation
Rails are horizontal members installed between posts. The calculator lets you choose 2, 3, 4 or 5 rails per section because the appropriate number depends on fence height, material and design. The total is sections multiplied by rails per section. Always follow the construction instructions for the fence system you are using.
Picket calculation
For individual pickets or boards, each board occupies its own width plus the gap before the next board. The calculator therefore uses the combined width and gap as the repeating pitch. The quantity is rounded up to cover the run and then increased by your waste allowance. A zero gap can be used for a close-boarded or privacy-style layout.
Panel calculation
If you choose pre-made panels, enter the usable width of one panel. The calculator divides the fence line by that width and rounds up, then applies the selected waste allowance. Check the manufacturer's actual coverage because nominal panel dimensions can differ from the usable width.
Concrete estimate
Concrete is estimated from the post-hole diameter and depth you enter. Hole volume uses the cylinder formula pi multiplied by radius squared multiplied by depth. The calculator subtracts the approximate square post volume so the concrete estimate represents the space around the post. The total volume is then divided by the concrete yield per bag and rounded up to a whole bag.
Why gates and corners matter
Gate posts carry the gate hardware and movement, so they should not be treated exactly like ordinary line posts. Corners and changes of direction also affect the number and arrangement of posts. Entering these separately makes the estimate more useful than simply dividing the fence length by a spacing value.
Worked example
For a 100 ft run with a 4 ft gate, 8 ft post spacing, three rails per section, 5.5 inch pickets, zero gap and 10% waste, the calculator first removes the gate opening, determines the required sections, adds the end and gate posts, then calculates rails, pickets and concrete. Your actual quantity will change with your measurements and chosen materials.
Important planning note
This tool is a material-planning estimate. It does not determine structural engineering requirements, local building codes, frost depth, wind-load requirements, soil conditions or permit requirements. Fence rules vary by location and construction type. Check local requirements and manufacturer installation instructions before building.
Frequently Asked Questions
How many fence posts do I need?
For a straight run, the basic calculation is sections plus one post. Gates and additional corners can require extra posts, so enter those separately.
What is common fence post spacing?
Six to eight feet is common for many residential wood fence layouts, but the correct spacing depends on fence height, material, wind exposure, panel size and installation requirements.
How many rails does a fence need?
It depends on the fence design and height. Some shorter fences use two rails while taller privacy fences commonly use three or more. Use the setting that matches your planned construction.
How many pickets do I need?
The calculator divides the fence line by the picket width plus the gap, rounds up and then applies your selected waste allowance.
How much concrete do fence posts need?
The estimate depends on the number of posts, hole diameter, hole depth and concrete yield per bag. Enter those values to estimate the total volume and bag count.
Does the fence calculator include gates?
Yes. Enter the number of gates and gate width. Gate openings are removed from the fence line and two dedicated gate posts are added for each gate.
Can it calculate fence cost?
Yes. Enter optional prices for posts, rails, pickets or panels and concrete bags to get an estimated material subtotal.
Can I use metres instead of feet?
Yes. The calculator supports metric and imperial units for the main dimensions and relevant material measurements.
Does the cost include labor?
No. The optional cost estimate covers only the material prices you enter. Labor, delivery, tools, permits and other project expenses are excluded.
