Free calculator
Fence Calculator
Enter a straight run of wood fence to get sections, posts, rails, pickets and bags of concrete. Add your own prices to get the installed cost, then add the run to an estimate and do the next one.
- Posts, rails, pickets, concrete
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Run
Pickets and rails
A 1×6 picket is 5½ in wide. Use a 0 in gap for a privacy fence.
Posts and concrete
Your prices
Optional. Saved in this browser, so you only type them once.
Gate is a complete gate or a kit; put hanging it in that price. Labor is per foot of fence, gate openings excluded.
Your estimate
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Nothing here yet. Run the numbers above and press “Add to estimate”.
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Fenced length. The run less the gate openings: run − gates × gate width. Gates are priced each, as a complete gate or a kit, so their pickets and frame are not in the counts.
Sections. Fenced length ÷ post spacing, rounded up. The last section takes whatever length is left.
Posts. Sections + gates + 1. A straight run with no gates takes one more post than it has sections. Each gate adds one, because the fence stops on both sides of it. This is the count on the Outdoor Essentials fence worksheet: one post per section, one to end the run and one per gate. Sections are counted on the fenced length as a whole, so if a gate leaves a short section on each side of it, add a post. Where two runs meet at a corner they share the corner post: take one off for each shared corner when you add runs together.
Post length. Fence height + hole depth, rounded up to the next even foot, because lumber is sold in 2-foot lengths. Gate posts are often a size up and set deeper; if yours are, price them on their own line.
Rails. Sections × rails per section. Outdoor Essentials calls for 2 backer rails per section on a 4-foot fence and 3 on a 6-foot fence. The calculator uses 3 at 5 feet and 4 at 8 feet as typical counts; change it to match your design. At 8 feet on center each 8-foot 2×4 spans one section. At 6 feet the calculator uses 12-foot rails that span two sections, so the count is halved and rounded up.
Pickets. Fenced length in inches ÷ (picket width + gap), rounded up, then your waste percentage added and rounded up again. A 1×6 picket is 5½ inches wide (AWC NDS Supplement, Table 1B). Outdoor Essentials recommends 10% extra. Picket length is the fence height.
Concrete. Per post: π × (hole diameter ÷ 2)² × depth, less the post’s cross-section × depth, ÷ 1,728 for cubic feet. A 4×4 is 3½ inches square and a 6×6 is 5½. All posts are totaled, then divided by the bag yield and rounded up. Quikrete’s data sheet for its Concrete Mix gives about 0.30, 0.45 and 0.60 cubic feet per 40, 60 and 80-lb bag. Other mixes, including fast-setting post mixes, yield differently, so check the bag. The count fills each hole from the bottom of the post to grade; a gravel base under the post or stopping a few inches below grade uses a little less.
Hole size. Quikrete’s guideline for setting posts is a hole about 3 times the post’s width across and 1/3 to 1/2 as deep as the post stands above ground. Below that, depth is a local call: the frost line, the soil and your city’s code. The defaults are a starting point, not a rule. An 8-foot fence is taller than the 7 feet that IRC Section R105.2 exempts from a building permit, so check whether your city wants a permit for it.
Price. Materials are quantity × your unit price for each item you priced. Gates are the count × your gate price. Labor is the fenced length × your rate per linear foot. Nothing is priced with numbers you did not enter.
Pricing the whole job? The fence estimate template has a takeoff sheet for several runs, corners and gates, and a customer-facing estimate with removal, gates and the permit as their own lines.
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Frequently asked questions
How many pickets do I need for an 8-foot fence section?
An 8-foot section is 96 inches. With 1×6 pickets, which are 5½ inches wide, butted tight for privacy, that is 96 ÷ 5.5 = 17.5, so 18 pickets. With a 2-inch gap it is 96 ÷ 7.5 = 12.8, so 13. Outdoor Essentials recommends adding 10% to the count, which makes 20 and 15. For a whole run, the calculator counts pickets on the full fenced length, then adds your waste.
How many posts do I need for a 100-foot fence?
On 8-foot spacing, 100 feet is 12.5 sections, rounded up to 13, and a straight run takes one more post than it has sections: 14 posts. A gate adds a post, because the fence stops on both sides of it. A 4-foot gate in the same 100 feet leaves 96 feet of fence in 12 sections, so it is 12 + 1 gate + 1 = 14 posts. Where two runs meet at a corner they share the corner post, so take one post off for each shared corner when you add runs together.
How much concrete do I need per fence post?
Work out the concrete around the post: π × (hole diameter ÷ 2)² × depth, less the post, divided by 1,728 for cubic feet. A 10-inch hole 24 inches deep around a 4×4 takes 0.92 cubic feet. That is 1.5 80-lb bags at Quikrete’s 0.60 cubic feet per bag, or 2.0 60-lb bags. At 30 inches deep it is 1.15 cubic feet, or 1.9 80-lb bags. The calculator totals the concrete for every post before it rounds up to whole bags.
Should fence posts be 6 or 8 feet apart?
Both are standard for wood fence. At 8 feet on center each section takes one 8-foot rail and you dig the fewest holes. At 6 feet the fence is stiffer and stands up better to wind, which suits a tall privacy fence or an exposed site. It costs holes: a 100-foot run with no gates takes 14 posts at 8 feet and 18 at 6 feet, which with 10 × 24-inch holes is 22 bags of 80-lb concrete against 28. At 6 feet the calculator uses 12-foot rails that span two sections each.
How deep should fence posts be set?
Quikrete’s guideline is a hole 1/3 to 1/2 as deep as the post stands above ground, which is 24 to 36 inches for a 6-foot fence, and about 3 times the post’s width across. Where the ground freezes, many contractors set posts below the frost line so frost heave does not lift them. Frost depth is set locally: footing depths in adopted building codes run from 12 inches in Cheatham County, Tennessee to 5 feet in northern Minnesota, and your building department lists yours with its IRC Section R301.2 design criteria. The city or HOA may also set a minimum. The depth you enter sets the post length: a 6-foot fence needs 8-foot posts at 24 inches deep and 10-foot posts at 30 inches.
How many more pickets does a privacy fence take than a spaced picket fence?
Only the gap changes the count. Privacy pickets are butted with no gap; spaced pickets leave one. On a 120-foot run with one 4-foot gate, 1×6 pickets butted tight take 280 with 10% waste, and with 2-inch gaps 205. Wood shrinks across its width as it dries, so pickets butted tight while still wet can open thin gaps. A solid fence also catches more wind than a spaced one, which is a reason to tighten the post spacing on a tall privacy fence.
Are my measurements and prices sent to BuildWorkPro?
The calculator sends nothing: the math runs in your browser, and your prices and your estimate are saved in this browser’s local storage, never on our servers. The run is kept in the page address so you can bookmark or share a result; like any page address, it is recorded by our site analytics if you accept analytics cookies.