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Fence Gate Calculator

A gate in a fence line — its posts, its frame, and the hardware it hangs on.

An estimate of material — a heavy or wide gate may need bigger posts and hardware.

40' · 480 in · 40 ft · 12.192 m

40 ft

5% covers pickets split by a screw or culled for warp and knots. It is added once, to the pickets — the posts, rails and concrete are counted from the fence itself.

This page recalculates as you type. There is no Calculate button.

Answer

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Posts

6 posts

40 ft of fence · 5 bays · 6 posts in holes 27" deep

Pickets, with waste 86 pickets
Rails 10 2×4s · 2 a bay
Fence, gates left out 40 ft
Concrete 11 × 50 lb fast-setting
Gravel under the posts 4 × 50 lb bags (0.5 ft³)
Ticked items cost $459.50
More numbers
Post holes 27" deep, 10" across
Widest post spacing 8' on center
Even gap between pickets 2 7/16" at a 2 1/2" gap
DrawingThe project drawn to scale. Left: 40' × 3' 6".40'3' 6"Left

Buying noteCall 811 a few business days before you dig. It is the free national before-you-dig service: the utilities mark their lines, and every post hole needs it.
Buying noteYour frost depth is not set. Where the ground freezes, a post set above the frost line heaves: ask your building department for the depth (IRC Table R301.2(1)) and type it under Assumptions — every hole follows it.

Breakdown

Run or gate Measurements Qty Length Share
Left 40' Add ×1 40 ft

What to buy

Buying noteCall 811 a few business days before you dig. It is the free national before-you-dig service: the utilities mark their lines, and every post hole needs it.
Buying noteYour frost depth is not set. Where the ground freezes, a post set above the frost line heaves: ask your building department for the depth (IRC Table R301.2(1)) and type it under Assumptions — every hole follows it.

Ways to buy the concrete

The bags for every post hole together, by the shape of the holes. Every way is worked out; pick the one you will buy.

11 × 50 lb fast-setting Bags 11 Left over 0.1 ft³ Weight 550 lb Cost $87.78 Reference price $7.98. Type your store's.

Shopping list

6 6 × 8 ft $81.12 Reference price $1.69. Type your store's.
86 86 × 4 ft $154.80 Reference price $0.45. Type your store's.
10 10 × 8 ft $48.00 Reference price $0.60. Type your store's.
3 3 × 1 lb box (126) $32.91 Reference price $10.97. Type your store's. Reference price $37.97. Type your store's.
1 1 × 5 lb box (309) $32.97 Reference price $32.97. Type your store's.
6 6 × 4×4 caps $47.88 Reference price $7.98. Type your store's. Reference price $12.98. Type your store's.
11 11 × 50 lb fast-setting $87.78
4 4 × 50 lb bags (0.5 ft³) $21.92 Reference price $5.48. Type your store's.
Ticked items $459.50

Untick what you already have. Lumber is priced by the foot, beside its row; the concrete's bags are priced in the table above.

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How this was worked out

Every number below is yours. Each constant links to the row where you can change it.

Left 40' 40 ft
Posts 5 bays in 1 runs: 4 line + 2 end + 0 corner + 0 gate 6 posts

Change:Widest post spacing, wood

How deep a post goes 0.5 × 42" out of the ground, or the frost depth 0" where deeper 21" + 6" = 27"

Change:Post in the ground, share of its height aboveYour frost depthGravel in the bottom of a hole

Posts, length 42" + 21" = 63" 6 × 8 ft
Concrete, each post (π ÷ 4 × 10" × 10" − 3 1/2" × 3 1/2") × 17 1/2" 0.671 ft³ × 6 = 4.028 ft³

Change:Hole across, 4×4 postConcrete stops under the ground

Bags of concrete 4.028 ft³ ÷ 0.375 ft³ 10.74 → 11 × 50 lb fast-setting

Change:Yield, 50 lb fast-setting bag

Gravel under the posts π ÷ 4 × 10" × 10" × 6" × 6 1.636 ft³ → 4 × 50 lb bags (0.5 ft³)

Change:Gravel in the bottom of a hole

Rails 5 × 2 = 10 10 × 8 ft

Change:A rail every

Pickets, edge to edge (480" + 2 1/2") ÷ (3 1/2" + 2 1/2") 81 × 4 ft

Change:Gap between picketsGap under the pickets

With the waste for culls 81 × (1 + 5%) 85.05 → 86
Screws 81 pickets × 2 rails × 2 + 10 boards × 2 ends × 2 324 + 40

Change:Screws where a picket crosses a railScrews at each end of a rail

What it comes to 6 × 8 ft × $1.69/ft + 86 × 4 ft × $0.45/ft + 10 × 8 ft × $0.60/ft + 3 × $10.97 + 1 × $32.97 + 11 × $7.98 + 4 × $5.48 $459.50

Assumptions

Every one of these is editable. Change one and the answer changes with it.

Assumption Value Confidence
Widest post spacing, woodPosts of a wood fence no more than 8 ft apart, center to center: the spacing Inch Calculator and Omni both work at, and the length of the 2×4 rail that spans a bay. ≈ in Trade convention
A rail everyOne rail for every 24 in of fence height, never fewer than a top and a bottom one: Inch Calculator's rule - three rails on a 6 ft fence, two up to 4 ft. ~ in Derived or single-supplier
Gap between picketsThe gap between pickets of a picket fence. Omni's fence FAQ works at 2½ in, Inch Calculator at 2 in; no maker read gives one. ~ in Derived or single-supplier
Gap under the picketsPickets stop about 2 in above the ground so they do not wick water; Freedom's vinyl kit sets its panels about 2 in up, and 2 in is the most ISPSC 305.2.1 allows over grass or gravel. ≈ in Trade convention
Screws where a picket crosses a railTwo screws where each picket crosses a rail, the usual nailing of a privacy fence. ~ screws Derived or single-supplier
Screws at each end of a railTwo screws at each end of a rail or a gate board, into the post or the frame. ~ screws Derived or single-supplier
Post in the ground, share of its height aboveQuikrete Fast-Setting Concrete Mix spec sheet, section 5: a post hole one half as deep as the post stands above ground. Quikrete's Setting Posts sheet says the same as one third of the post's length, and so does Home Depot's chain link guide for its posts. ratio From a data sheet or an agency document
Your frost depthYour frost depth, from your building department (IRC Table R301.2(1) is filled in locally). 0 means not given: every hole is then as deep as the post's own rule. Typed in, no hole stops above it. ≈ in Trade convention
Gravel in the bottom of a holeQuikrete Setting Posts, step 2: 6 in of gravel or crushed stone in the bottom of the hole, for drainage. in From a data sheet or an agency document
Concrete stops under the groundQuikrete Setting Posts, steps 4 and 6: fill the hole to 3-4 in below the top, then finish with soil. The middle of the range. in From a data sheet or an agency document
Hole across, 4×4 postQuikrete Fast-Setting spec sheet, section 3: a 4 in post set in a 10 in hole. Its rule of three times the post would make 10½ in for a 4×4. in From a data sheet or an agency document
Hole across, 6×6 postA 6×6 gate post. Quikrete's three times the post would be 16½ in, a hole few dig for a fence; 12 in is an auger's size. ~ in Derived or single-supplier
Yield, 50 lb fast-setting bagQuikrete Fast-Setting Concrete Mix spec sheet. ft³/bag From a data sheet or an agency document

What a fence gate takes

A gate is a gap in the fence with a post either side and a leaf hung between them. A 12 foot driveway gate in a 6 foot wood fence is two leaves of 6 feet, and it takes two 6×6 gate posts, each 10 feet long, set 36 inches deep in a 12 inch hole; six hinges, three to a leaf because each leaf is 6 feet tall; one latch; and one drop rod — the cane bolt that pins the fixed leaf to the ground so the other has something to latch to.

A wood gate is built from the fence's own lumber. Each leaf is a frame of three 2×4 rails, one for every 24 inches of height as on the fence, and a brace from the bottom of the hinge side to the top of the latch side, so the leaf hangs from its hinges instead of sagging toward the latch. A 6 foot leaf takes its rails from 8 foot boards and its brace, about 8 feet 4 inches long, from a 10 foot one. Its face is covered with the same pickets as the fence, 14 to a leaf.

Single or double

A walk gate is one leaf, usually 3½ to 4 feet; a drive gate is two leaves meeting in the middle. In the parts list choose Gate, one leaf or Gate, two leaves and type the opening. A double gate needs the drop rod and a latch that holds two leaves; a single gate needs neither.

Hinges

A leaf up to 5 feet tall hangs on a pair of hinges; from 6 feet it takes three, which is what Hoover Fence advises for wood gates. Both figures are under Assumptions. Heavy-duty strap or tee hinges carry a wood leaf; a chain link, vinyl or aluminum gate comes made, often with its hinges and latch — untick those rows if yours does.

Gate posts

A gate post carries a swinging leaf, so it is a 6×6 on a wood fence where the line posts are 4×4, in a wider hole with more concrete: 1.558 cubic feet each against 1.247 for a line post. Hang the gate before the fence pickets go on either side of it, and leave the gap the hinge and latch need. We are not connected with any maker, store or supplier named here.