Measure the fence path before choosing Post positions
This calculator divides each straight Run into equal clear Bays and lists every Post center along the path. It is useful when laying out a site-built fence with Runs, Gates and right-angle Corners. It does not optimize fixed-width manufactured panels: equalizing every opening can leave no opening that matches an uncut panel.
Measure a Run from the outside face of its first Post to the outside face of its last Post. Enter the actual square Post width, not its nominal lumber size. Maximum Bay is a limit on the clear opening between Post faces, not on center-to-center spacing. If your system specifies centers, establish the corresponding clear opening before entering a value. The tool’s default 8 ft is an example input, not a structural recommendation.
A 40 ft Run you can check by hand
For this arithmetic example, keep one Run of 40 ft, remove the Gate, Corner and second Run, set Post width to 3.5 in and Maximum Bay to 8 ft. Overall Length is 480 in and the maximum clear opening is 96 in.
The model chooses five Bays: round (480 − 2 × 3.5) / 96 upward to a whole number. Five Bays need six Posts. Deduct all six Post widths, then divide the remaining opening equally:
- Total clear space:
480 − 6 × 3.5 = 459 in. - Each Bay:
459 / 5 = 91.8 inclear. - Center-to-center step:
91.8 + 3.5 = 95.3 in. - First Post center:
3.5 / 2 = 1.75 infrom the starting outside face.
| Post | Center from starting outside face, inches |
|---|---|
| P1 | 1.75 |
| P2 | 97.05 |
| P3 | 192.35 |
| P4 | 287.65 |
| P5 | 382.95 |
| P6 | 478.25 |
These are unrounded arithmetic positions. The tool displays inches to the nearest 1/16, so its labels can differ slightly from the decimal table. Check the far boundary: 478.25 + 1.75 = 480 in. Measure each mark from the same origin instead of repeatedly adding rounded steps. The five clear openings plus six Post widths must recover your full measured Run.
Add Gates and Corners without double-counting Posts
A Gate uses leaf width plus hinge and latch allowances to establish its clear opening. It shares the neighboring boundary Posts; it does not add a fence Bay or estimate the Gate leaf’s framing. Enter allowances from your hardware instructions. A Corner turns the path right by 90 degrees around the preceding Post center and adds no extra Post. Put a Run or Gate on each side of the Corner.
The starting example includes 40 ft and 24 ft Runs, a 4 ft Gate with two 3/8 in allowances, and a Corner. It produces ten unique Posts. That is a different plan from the six-Post single-Run example above. Adding the Post counts for separate segments would double-count shared boundaries.
“Along Plan” follows the centerline around the path; it is not a straight tape measurement across a diagonal. Each Run also lists local centers from that Run’s outside face. Use the plan drawing to identify the Post, then use the appropriate local origin on site. Closed loops, intersections, slopes and arbitrary angles are not inferred.
What the materials estimate includes
The Post-only result lists Posts and a concrete estimate; it does not buy pickets or Rails. Post length is the entered above-ground height plus buried length. Concrete uses a circular hole with the square Post volume removed, divided by the selected bag yield and rounded up. You must supply the footing dimensions independently. This tool does not decide soil suitability, frost depth, structural loading or a safe span.
Confirm actual mix yield and the selected fence system before purchasing. Record Gate leaves, hinges, latches, brackets and any extra structural Posts separately. For installed pickets and Rail cuts, use the picket fence planner.
Save and use the result
Use Copy plan link to retain the inputs and restore the same plan on another device. Print plan prints the diagram, Post centers and material quantities; this page does not provide a full-size Post marking strip. Verify measurements on site before digging. Read the 6 ft versus 8 ft spacing guide, Gate layout guide and published formulas for the assumptions behind these results.
For manufactured assemblies, use the fence panel width and Post spacing guide to compare actual product dimensions and a worked full-panel quantity example. The Post calculator equalizes Bays; it does not preserve fixed panel widths.