Before you measure
- Confirm the property line. A survey or the plat for your lot shows where the line is. Fences built over the line cause disputes.
- Check the rules. Cities and HOAs often limit fence height (commonly lower in front yards), set required setbacks, and may require a permit or a particular "good side out".
- Call 811 (US) a few days before digging so buried utilities get marked. It's free.
How to measure a fence line
- Stake the corners and ends and pull a string between them. Each straight stretch between two stakes is a run.
- Measure each run along the ground and enter it, adding the others with “+ Another run”. On a slope, also note how much the ground rises or falls from one end of the run to the other.
- Mark the gates in each run and measure the opening you want. Every gate gets a post on each side.
- Choose how the runs meet: joined at corners (an L or U shape, which shares the corner posts), a closed loop (the last run comes back to the first), or separate pieces that each need their own end posts.
How the parts are counted
- Sections: each run is split by its gates into pieces. With one gate, a run becomes two pieces. Each piece is divided into equal sections no longer than the post spacing.
- Posts = sections + pieces in each run, less one shared post at every corner where runs join. Gate posts are the ends of the pieces either side of each gate.
- Post types: corner posts where runs meet, end posts at the open ends, 2 gate posts per gate, and line posts for the rest. Corner, end and gate posts take the most load, so set them carefully in concrete.
- Rails = sections × rails per section. Pickets = level fence length (gates left out) in inches ÷ (picket width + gap), plus waste.
- Concrete per hole = π × (hole diameter ÷ 2)² × (hole depth − gravel) − the post's own volume in the concrete. Divide by about 0.6 ft³ per 80 lb bag, as the post hole calculator does.
With the defaults (one 100 ft run, a 4 ft gate, 8 ft spacing, 6 ft high, 3 rails, 5.5 in pickets with no gap) you get 14 posts, 38 rails and 230 pickets. The gate opening replaces part of a section, so a gate doesn't always add a post. Without the gate it's also 14 posts, but in 13 sections instead of 12.
Sloped ground: racked or stepped
Enter the height change along each run. The run length is measured along the ground, so the level distance is a little shorter.
- Racked panels follow the slope, with the rails parallel to the ground. Pickets stand vertical, so they are counted over the level distance.
- Stepped panels stay level and step down at each post. Each step is about the rise ÷ the number of sections. The post on the low side of each step needs that much extra height, so the calculator adds it to the post length, and the triangle-shaped gap under each panel grows on the downhill side.
| Height change over a 100 ft runHeight change over a 30.5 m run | Pickets (racked) | Step per section (stepped) | Post length (stepped) |
|---|---|---|---|
| 0 ft0 m | 230 | 0 | 8 ft2.44 m |
| 4 ft1.22 m | 229 | 3.7 in9.4 cm | 8.3 ft2.53 m |
| 8 ft2.44 m | 229 | 7.4 in18.8 cm | 8.6 ft2.62 m |
| 16 ft4.88 m | 227 | 14.8 in37.5 cm | 9.2 ft2.8 m |
Picket styles and how to enter them
- Side-by-side privacy: pickets butted together. Enter gap = 0. Wood shrinks as it dries, so small gaps usually open up anyway.
- Spaced picket: enter the gap you want, for example 2½ in for a classic picket look.
- Board-on-board (shadowbox): boards alternate front and back of the rails and overlap. Each board adds its width minus one overlap of coverage. So enter the picket width as (board width − overlap) and gap = 0. With 5.5 in boards and 1.5 in overlap, enter 4 in. That takes 300 boards for 100 ft, compared with 219 for side-by-side.
| Style | Effective width | Pickets per 8 ft section | Pickets per 100 ft (no waste) |
|---|---|---|---|
| Side-by-side 5.5 in | 5.5 in | 18 | 219 |
| Spaced, 3.5 in picket + 2.5 in gap | 6 in | 16 | 200 |
| Board-on-board, 5.5 in with 1.5 in overlap | 4 in | 24 | 300 |
| Side-by-side 3.5 in | 3.5 in | 28 | 343 |
| Style | Effective width | Pickets per 2.4 m section | Pickets per 30 m (no waste) |
|---|---|---|---|
| Side-by-side 14 cm | 14 cm | 18 | 215 |
| Spaced, 9 cm picket + 6 cm gap | 15 cm | 16 | 200 |
| Board-on-board, 14 cm with 4 cm overlap | 10 cm | 24 | 300 |
| Side-by-side 9 cm | 9 cm | 27 | 334 |
Post spacing, rails and post depth
Wood privacy fences usually have posts 6–8 ft on center. 8 ft matches common rail lengths, and closer spacing makes a stiffer fence in windy areas. Many 6 ft privacy fences use three rails (top, middle and bottom), and shorter fences often use two. That's a widely used rule of thumb rather than a code requirement. For post holes, Quikrete's guidance is a hole about three times the post width, 1/3 to 1/2 of the above-ground height deep, plus 6 in of gravel. A 6 ft fence needs at least 2 ft of embedment, so 8 ft posts are the usual buy. The calculator shows the post length from your fence height and hole depth. Use posts rated for ground contact, and consider heavier posts for wide gates.
Worked examples
Backyard privacy fence on three sides (50 + 100 + 50 ft) with a gate in each side runBackyard privacy fence on three sides (15.2 + 30.5 + 15.2 m) with a gate in each side run
Run length 50 ft · Gates in this run 1 · Post spacing 8 ft · Fence height 6 ft · Rails per section 3 · Picket width 5.5 in · Gap between pickets 0 in · Waste / overage 5 %Run length 15.24 m · Gates in this run 1 · Post spacing 2.44 m · Fence height 1.83 m · Rails per section 3 · Picket width 14 cm · Gap between pickets 0 cm · Waste / overage 5 %
- Pickets: 459
- Posts: 28
- Line posts: 20
- Corner posts: 2
- End posts: 2
- Gate posts: 4
- Rails (8 ft sections): 79Rails (2.44 m sections): 79
- 80 lb concrete bags for posts: 4625 kg concrete bags for posts: 66
Closed loop around a 60 × 40 ft plot with one gateClosed loop around an 18.3 × 12.2 m plot with one gate
Run length 60 ft · Gates in this run 1 · How the runs meet Closed loop · Post spacing 8 ft · Fence height 6 ft · Rails per section 3 · Picket width 5.5 in · Gap between pickets 0 in · Waste / overage 5 %Run length 18.29 m · Gates in this run 1 · How the runs meet Closed loop · Post spacing 2.44 m · Fence height 1.83 m · Rails per section 3 · Picket width 14 cm · Gap between pickets 0 cm · Waste / overage 5 %
- Posts: 27
- Corner posts: 4
- Gate posts: 2
- Rails (8 ft sections): 82Rails (2.44 m sections): 82
- Pickets: 459
Hillside run, 80 ft along the ground with 8 ft of fall, stepped panelsHillside run, 24.4 m along the ground with 2.44 m of fall, stepped panels
Run length 80 ft · Height change along the run 8 ft · Gates in this run 0 · Post spacing 8 ft · Fence height 6 ft · On sloped runs Stepped (level) · Rails per section 3 · Picket width 5.5 in · Gap between pickets 0 in · Waste / overage 5 %Run length 24.38 m · Height change along the run 2.44 m · Gates in this run 0 · Post spacing 2.44 m · Fence height 1.83 m · On sloped runs Stepped (level) · Rails per section 3 · Picket width 14 cm · Gap between pickets 0 cm · Waste / overage 5 %
- Pickets: 183
- Posts: 11
- Sections: 10
- Post length (with the tallest step): 8.8 ftPost length (with the tallest step): 2.7 m
Front picket fence, 60 ft, 4 ft high, 2 rails, 3.5 in pickets with 2.5 in gaps, 24 in holesFront picket fence, 18.3 m, 1.22 m high, 2 rails, 8.9 cm pickets with 6.3 cm gaps, 61 cm holes
Run length 60 ft · Gates in this run 1 · Post spacing 8 ft · Fence height 4 ft · Rails per section 2 · Picket width 3.5 in · Gap between pickets 2.5 in · Waste / overage 5 % · Post hole depth 24 inRun length 18.29 m · Gates in this run 1 · Post spacing 2.44 m · Fence height 1.22 m · Rails per section 2 · Picket width 8.9 cm · Gap between pickets 6.4 cm · Waste / overage 5 % · Post hole depth 61 cm
- Pickets: 126
- Posts: 10
- Rails (8 ft sections): 17Rails (2.44 m sections): 17
- Concrete per hole: 0.03 yd³ (0.7 ft³)Concrete per hole: 0.02 m³ (20 L)
- 80 lb concrete bags for posts: 1325 kg concrete bags for posts: 18
The shopping list
The results double as a shopping list: pickets, posts by type, rails, gate kits, concrete, gravel, post caps and fasteners, with costs if you enter prices. Use “Add to project” to keep it with your other jobs. Also remember:
- Fasteners: the calculator counts 2 per picket at each rail as a budgeting figure. Use exterior-rated, corrosion-resistant nails or screws. Treated lumber calls for hot-dip galvanized or stainless fasteners.
- Rail brackets or hangers if you're not toenailing rails: 2 per rail.
- Gate kit per gate: hinges and a latch, plus a drop rod for double gates. An anti-sag cable kit helps on wide gates.
- Stain or sealer: use the paint calculator with the fence area (length × height × 2 sides) and the product's coverage rate.
Common mistakes
- Entering an L- or U-shaped fence as separate runs, which adds end posts you don't need. Join them at corners instead.
- Buying 6 ft posts for a 6 ft fence. Part of the post goes in the ground, and stepped fences need even longer posts on the low side.
- Spacing posts by eye. Measure the centers so standard rails fit without much cutting.
- Setting gate posts in gravel. Gates pull sideways, so set gate posts in concrete.
- Forgetting the gate width. The opening is fence you don't need to buy pickets for, but it still needs two posts and a gate.
Checked against
Each case below is re-run against the calculator by our automated test suite.
| Case | Our result | Checked against | Result |
|---|---|---|---|
| 100 ft fence, posts 8 ft apart, no gate: posts | 14 | InchCalculator.com fence calculator (worked examples) | Match |
| Same fence, 3 rails per section, no waste: rails | 39 | InchCalculator.com fence calculator (worked examples) | Match |
| Same fence, 5.5 in pickets with 2 in gaps, no waste: pickets | 160 | InchCalculator.com fence calculator (worked examples) | Match |
| 100 ft run with one 4 ft gate: posts (two 48 ft pieces of 6 sections) | 14 | Hand calculation | Match. Adding a post per gate would give 15, but the gate opening also removes a section. |
| L-shaped fence, 60 ft + 40 ft runs joined at a corner, no gates: posts | 14 | Hand calculation | Match |
| 10 in hole, 30 in deep with 6 in gravel, 3.5 in post: concrete per hole | 0.03 yd³ (0.9 ft³) | Hand calculation | Match |
| Case | Our result | Checked against | Result |
|---|---|---|---|
| 30.5 m fence, posts 2.44 m apart, no gate: posts | 14 | InchCalculator.com fence calculator (worked examples) | Match |
| Same fence, 3 rails per section, no waste: rails | 39 | InchCalculator.com fence calculator (worked examples) | Match |
| Same fence, 14 cm pickets with 5.1 cm gaps, no waste: pickets | 160 | InchCalculator.com fence calculator (worked examples) | Match |
| 30.5 m run with one 1.22 m gate: posts (two 14.6 m pieces of 6 sections) | 14 | Hand calculation | Match. Adding a post per gate would give 15, but the gate opening also removes a section. |
| L-shaped fence, 18.3 m + 12.2 m runs joined at a corner, no gates: posts | 14 | Hand calculation | Match |
| 25.4 cm hole, 76.2 cm deep with 15.2 cm gravel, 8.9 cm post: concrete per hole | 0.026 m³ (26 L) | Hand calculation | Match |
Frequently asked questions
How many pickets for a 100 ft fence?
With 5.5 in pickets side by side, 219 before waste, or 230 with 5%. A 4 ft gate takes about 9 pickets off the fence itself.
How far apart should fence posts be?
For wood privacy fences, usually 6–8 ft on center. 8 ft matches standard rail lengths.
How many posts for a 100 ft fence?
At 8 ft spacing with no gate: 13 sections and 14 posts. With a 4 ft gate in the middle it is still 14, because the gate opening replaces part of a section and its two posts end the fence on either side.
How many posts do I need at a corner?
One. When runs join, the corner post ends both runs. Enter the runs as “joined at corners” and the calculator shares that post.
How many bags of concrete per fence post?
For a 10 in hole 30 in deep with 6 in of gravel and a 4×4 post, about 1.6 bags of 80 lb mix with 5% waste. Enter your hole size for your own figure.
How do I build a fence on a slope?
Rack the panels to follow gentle slopes, or step level panels down steeper ones. Enter the height change for each run, and the calculator adjusts the pickets and post lengths.
Sources & assumptions
The results are planning estimates, and the cost figures only use prices you enter. Product yields, densities and coverage rates vary, so check the label or ask your supplier, and follow local codes. Figures marked "approximate" or "rule of thumb" are general practice, not exact standards.
- Quikrete: Setting Posts in Concrete
- 811: Know what's below, call before you dig
- NIST Voluntary Product Standard PS 20-25 (American Softwood Lumber Standard), Table 3: dressed sizes
- InchCalculator.com fence calculator (compared in our checks)
See how we calculate and test our formulas and the changelog. Last updated 2026-10-08.
Reviewed by the MaterialWhiz Editorial Team. This estimate uses the assumptions shown in the calculator. Review the result against your supplier's product coverage and site conditions. Last reviewed: October 10, 2026. See how we calculate · Report a correction.