Fence calculator app: free fence estimator for Android, iPhone and web (2026)

A fence estimate goes wrong in the same three places every time: corners and gates get double-counted, the last bay ends up as a 2-foot stub, and nobody remembers the concrete. A good fence calculator app fixes those by working from the fence line (runs, corners and gates) instead of one total length. Here's what to look for, the math to check any app against, and the free options for Android, iPhone and the web.

Short answer: on Android, Smart Fencing Calculator is free on Google Play (with ads). On iPhone, the fence calculator lives inside Roofing Calculator & Estimator (version 1.7 and later). On a laptop, use the free calculators at smartfencingcalculator.com.

Fence estimating options compared

The fence math any app should match

Posts

For one straight run, posts = (run length ÷ post spacing, rounded up) + 1. A 100 ft run at 8 ft spacing is 12.5 bays, rounded up to 13, so 14 posts. Rounding up leaves one short bay; a good calculator spreads the bays evenly instead (13 bays of about 7 ft 8 in). Where two runs meet at a corner they share a post, so count it once. Gates usually need their own heavier posts on both sides.

Pickets

Pickets per bay = bay width ÷ (picket width + gap). Actual picket widths are smaller than nominal: a "1×6" picket is about 5½ in wide. An 8 ft (96 in) bay with 5½ in pickets and a ¼ in gap needs 96 ÷ 5.75 ≈ 16.7, so 17 pickets. Butted tight for privacy, it's 96 ÷ 5.5 ≈ 17.5, so 18. Add a few percent for split or warped boards.

Rails and concrete

Most wood privacy fences use two rails per bay up to about 4 ft high and three for 6 ft. Post-hole depth and concrete depend on post length, soil and your local frost line; check your local building department before digging, and call 811 to have buried utilities marked.

What's in Smart Fencing Calculator

From its Google Play listing (checked October 3, 2026):

• a Fence Line Planner: add each run and its gates, and runs that connect at corners share their posts;
• wood privacy, picket, board-on-board, shadowbox, horizontal, split rail, vinyl, aluminum, composite, chain link, barbed wire, electric and welded wire fences;
• posts evened out so the last bay is never a stub, and a drawn top-down plan with every post, corner and gate;
• a shopping list grouped by posts, rails, boards, concrete, hardware, gates and finish, with tick boxes;
• a picket spacing solver, fence panel calculator, gate builder and slope (step or rack) tools;
• PDF export of the plan, or turn it into a quote.

On iPhone

There's no separate fence app on the App Store from us. The fence calculators are part of Roofing Calculator & Estimator, which also covers roofs, decks, drywall, insulation, tile, sod and gravel, so one free app handles most exterior jobs.

Prefer the browser or a spreadsheet?

smartfencingcalculator.com has free fence, post and picket calculators that run in any browser. For office estimating, the fence material estimator workbook takes one row per straight run and counts posts (with shared corners and gate posts), pickets with waste, rails and concrete. For a cost walkthrough, read our fence cost calculator guide.