Double Gate Calculator
Calculate exact frame widths for each leaf of a double driveway gate with hinge clearances and center drop rod spacing.
Double gate leaf width
Enter your measurements and the result updates as you type.
Overview
Building a double-driveway or equipment gate requires accounting for clearances on both outer hinge posts plus the center meeting gap where latches and cane bolts operate.
This calculator takes your total post-to-post clear opening and calculates the precise frame width for each gate leaf so your double gate closes smoothly without binding.
Common mistakes
- Building gate frames to exactly half the opening width without subtracting hinge hardware and center drop rod clearances.
- Using standard 4x4 posts for wide double gates, resulting in post bending and center gate sag.
- Omitting diagonal cross-braces, or installing braces running the wrong direction (tension vs compression).
- Ignoring ground slope and driveway crown, causing gate leaves to drag on pavement when opened.
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Related reading
In-depth guides
Frequently asked questions
How much clearance is needed between posts and double gate frames?
Allow roughly 1.5 to 2 inches total for outer hinges (3/4 to 1 in per side) and 1/2 to 3/4 inch in the center for the latch and drop rod.
What size posts are needed for a 12-foot double gate?
Each leaf of a 12-foot double gate is 6 feet wide. Use at least 6x6 pressure-treated wood posts buried 36 to 48 inches deep in concrete to avoid sagging.
Which direction should the diagonal gate brace run?
Wood compression braces must run diagonally upward from the bottom hinge corner to the top latch corner to transfer weight back to the lower hinge.
How do you secure the center of a double swing gate?
Install a heavy-duty cane bolt (drop rod) on one stationary leaf that slides into a pipe sleeve embedded in the driveway ground, and latch the active leaf to it.
What is the best width for a riding lawn mower gate?
Standard riding mowers require at least a 5 to 6-foot single gate or a 10-foot double gate to clear mower decks with discharge chutes.
Can you automate a double swing driveway gate?
Yes. Dual electric gate openers mount on the hinge posts and attach to horizontal structural crossbars on each gate leaf.
What hardware is best for heavy wooden double gates?
Use heavy steel strap hinges (12 to 18 inches long) through-bolted with carriage bolts, an anti-sag steel turnbuckle cable kit, and a heavy cane drop rod.
How do you prevent a double driveway gate from dragging?
Set posts deeply in oversized concrete footings, install diagonal cross-braces, use adjustable turnbuckles, and allow 3 to 4 inches of ground clearance.