Why do fence gates sag?

Fence gates sag because they are cantilevered structures — the weight of the gate hangs off the hinge post on one side, constantly pulling that corner down and away. Over time, this force causes the gate frame to rack (go out of square), which drops the latch-side corner toward the ground. Contributing factors include: heavy gate material (solid wood gates sag faster than lighter options), loose or undersized hinges that allow the gate to shift on the post, a hinge post that is leaning toward the gate, wood frame joints that have loosened, and inadequate diagonal bracing in the gate frame. A gate that was never braced diagonally from the hinge-top corner to the latch-bottom corner will sag as a matter of physics — gravity always wins without a compression or tension element in the frame.

What is an anti-sag gate kit and does it work?

An anti-sag gate kit (sold under names like National Hardware Anti-Sag Gate Kit, Adjust-A-Gate, and others) is a turnbuckle and steel cable assembly designed to apply tension diagonally across the gate frame from the top-hinge corner to the bottom-latch corner. This tension counteracts the racking force that causes sagging. They do work — for gates that are already well-built but have developed a sag due to loosened joints or gradual racking, an anti-sag kit can restore squareness and maintain it. The kit will NOT fix a gate with a leaning or failing hinge post, because the problem is the post rather than the gate itself.

How do I know if my hinge post is the problem?

Stand at the gate and look at the hinge post. Use a level on the face of the post. If the post leans toward the gate (away from the fence line), it is the primary cause of sagging. A leaning hinge post means the post is failing at or below ground level — either the concrete footing cracked, the wood rotted, or the post was set too shallow. No amount of gate adjustment will permanently fix a sag caused by a failing post. The post must be repaired or replaced first. Check by probing the post at ground level with a screwdriver — if it sinks into soft, dark wood, the post is rotted and needs replacement.

My gate won't latch — the latch is too far from the strike. What do I do?

If the gate is sagging but otherwise structurally sound, the latch misalignment can often be corrected by squaring the gate frame (with an anti-sag kit) combined with adjusting the latch strike position. If the strike is on a vertical post: loosen or remove the strike, slide it to the correct height, and re-mount it. Many gate latches have adjustment slots rather than fixed holes for exactly this reason. If the gap between the gate and the post at the latch side is uneven (wider at bottom than top due to sag), straightening the gate frame is the only real fix — moving the latch down may work temporarily but won't address the ongoing racking.

What size hinges should a fence gate have?

Gate hinges are sized by the weight and width of the gate. For lightweight gates (under 50 lbs, under 4 feet wide): standard strap hinges or T-hinges in 6-inch size are adequate. For medium gates (50–100 lbs, 4–6 feet wide): heavy-duty strap hinges or lag-bolt hinges, 8–10 inches, with three hinges rather than two. For heavy gates (over 100 lbs) or wide gates: heavy-duty adjustable hinges or commercial gate hinges with ball bearings. Using undersized hinges is one of the most common causes of gate sag — the hinges flex under load, allowing the gate to shift. When in doubt, go heavier. Adding a third hinge in the center of a two-hinge gate significantly reduces the leverage on each hinge and can eliminate sag in borderline cases.

How do I square up a gate frame that has racked out of square?

To square a gate frame: first loosen or remove the gate from the hinges so you can work on it flat. Lay the gate on a flat surface (driveway or workbench). Measure the two diagonal dimensions corner to corner — if the gate is square, these measurements are equal. If not, apply a clamp across the longer diagonal to compress it while you add fasteners or apply the anti-sag cable. The anti-sag cable kit does the squaring in place without removing the gate, which is the most practical approach for most DIYers. Install the cable bracket at the top-hinge corner and the turnbuckle at the bottom-latch corner, then tighten the turnbuckle to draw that diagonal shorter — this pushes the gate back into square.

How to Fix a Sagging Fence Gate: Anti-Sag Kits, Hinge Adjustment, and Frame Repair (2026)

A sagging fence gate is one of the most common problems homeowners deal with, and most cases can be fixed in an afternoon without replacing the gate or posts.

A sagging fence gate is one of the most common problems homeowners deal with, and most cases can be fixed in an afternoon without replacing the gate or posts. This guide covers the full diagnostic process and every repair method, from a simple anti-sag cable kit to hinge replacement and gate frame rebuilding.

What You Need

Anti-sag gate kit with turnbuckle and cable
Heavy-duty gate hinges (galvanized or stainless, sized for gate weight)
Gate latch and strike kit
Structural wood screws (3”, exterior galvanized)
Post hole repair spike or E-Z Mender (if post is leaning)
Drill with driver bits
Level (4-foot is ideal)
Tape measure
Adjustable wrench and pliers

Step 1: Diagnose the Real Problem

Before buying parts or making repairs, identify the actual source of the sag. Fence gate repairs fail repeatedly when the repair targets the symptom (gate drooping) instead of the cause (leaning post, failed hinges, racked frame).

Check the hinge post first. This is the most important diagnostic step. Place a 4-foot level against the face of the hinge post. Read the bubble in two orientations: one with the level held vertically on the post face, and once with it held horizontally on the post top (checking for lean in both planes).

If the post leans toward the gate: the post is the problem. Repair the post before doing anything to the gate.
If the post is plumb and solid: the gate itself is the problem.

Inspect the hinges. With the gate closed, examine the hinge leaves and the screws holding them to the post and gate frame. Look for:

Screw holes that are stripped (screws spin freely without gripping)
Hinge leaves that have bent or deformed under load
Hinges that are undersized for the gate weight

Check the gate frame. Measure the diagonals of the gate from corner to corner. A square gate has equal diagonal measurements. If one diagonal is longer than the other, the frame has racked — that racking is what drops the latch-side corner.

Check for wood rot. Probe the gate frame rails and stiles (especially the bottom rail) with a screwdriver. If the screwdriver penetrates easily, there is rot. Rotted frame members must be replaced — they cannot hold fasteners.

Step 2: Fix a Leaning Hinge Post

If the hinge post is leaning, this must be addressed before any gate repair.

For a post that has shifted in firm soil (no rot): A metal fence post repair spike driven alongside the post provides support without excavation. Drive the spike 12–18 inches into the ground tight against the leaning post using a sledgehammer with the driving cap. Pull the post plumb using a come-along or helper, and bolt the spike to the post with lag screws through the spike’s pre-drilled holes.

For a rotted post: There is no repair for rotted wood. The post must be fully replaced. Dig out or jack out the old post and concrete footing, set a new pressure-treated post in the hole at the correct depth (one-third of total length underground, below frost line in cold climates), and set in fast-setting concrete. Brace the post plumb in two directions while the concrete cures — at least 4 hours before hanging the gate.

For a post that pulled away from its footing: This is a concrete failure or a post that was set without concrete (just packed dirt). Remove the post from the hole, inspect for rot, and reset it in fast-setting concrete at the correct depth.

Step 3: Fix Stripped Hinge Screws

Stripped screw holes are one of the most common hinge problems and one of the easiest to fix.

Method 1: Larger screws. Replace the existing screws with screws one size longer or one gauge thicker. A screw that was 2 inches long replaced by a 3-inch screw will reach fresh wood below the stripped zone.

Method 2: Wooden toothpick repair. For holes that are fully stripped: dip several wooden toothpicks in wood glue, pack them into the stripped hole, snap or trim them flush, and let the glue cure for at least an hour. Drive the original screws back into the repaired hole — the wood fibers from the toothpicks give the threads something to grip. This works reliably for most exterior applications.

Method 3: Lag screws. Replace standard wood screws in hinges with lag screws of the same diameter — the coarser threads of a lag screw grip better in end grain and in previously stripped holes. Pre-drill a pilot hole slightly smaller than the lag shank.

Method 4: Through-bolting. For gate posts or gate frame members that are too stripped or too damaged for screw repair, drill completely through the post or frame member and install a carriage bolt with a washer and nut on the back. This is the strongest possible hinge attachment and is recommended for heavy gates or high-traffic applications.

Step 4: Install an Anti-Sag Cable Kit

For a gate with a plumb post and solid hinges where the frame has racked, an anti-sag kit is the most efficient repair.

How it works. The kit consists of two corner brackets (with eyelets), a length of steel cable, and a turnbuckle. The brackets mount at the top-hinge corner and the bottom-latch corner of the gate. The cable runs diagonally between them, and the turnbuckle lets you tighten the cable to apply tension — pulling the bottom-latch corner up and pushing the gate frame back into square.

Installation:

Mount the corner bracket at the top-hinge corner. Position it on the inside face of the gate at the corner where the top rail meets the hinge-side stile. Drive the screws (provided in the kit) into solid wood.
Mount the second bracket (or the turnbuckle end, depending on the kit design) at the bottom-latch corner — where the bottom rail meets the latch-side stile.
Thread the cable through the eyelet at the top-hinge corner bracket, and through the turnbuckle at the bottom-latch corner. Follow the kit instructions for the specific cable attachment method — some use cable clamps, others use looped wire rope.
Tighten the turnbuckle gradually. As you tighten, the cable shortens the bottom-latch-to-top-hinge diagonal, which squares the gate frame. Watch the bottom of the gate rise away from the ground as tension increases.
Check square periodically as you tighten. Measure the diagonals — stop tightening when they are equal, or when the latch aligns with the strike.
Don’t overtighten. You want the gate square and the latch aligned — not the frame under structural stress. Over-tensioning can pull corner joints apart.

Step 5: Replace or Upgrade the Hinges

If the existing hinges are bent, too small for the gate weight, or the mounting surfaces are too damaged to hold screws reliably, replace the hinges entirely.

Sizing the new hinges:

For most residential wood fence gates (under 50 lbs, under 4 feet wide): 6-inch heavy-duty strap hinges or T-hinges are adequate. Use galvanized or stainless steel — never uncoated steel outdoors.

For gates 4 to 6 feet wide or over 50 lbs: use 8-inch or 10-inch strap hinges with at least 3/16-inch leaf thickness, and consider adding a third hinge at the midpoint of the gate to reduce leverage on each hinge.

For very heavy gates (solid board gates over 6 feet tall): heavy-duty gate hinges with lag-bolt mounting through the post, or weld-on hinges for steel post applications.

Removing old hinges and installing new ones:

Remove the gate from the hinges (have a helper hold it). Remove the old hinges from the post and gate frame. Examine the old mounting locations — if the wood is severely damaged, shift the new hinge position slightly up or down to reach solid wood, or use the toothpick repair method on the old holes before installing.

Mount the post-side hinge leaves first, using 3-inch exterior structural screws or lag bolts. Check that the hinge barrels are aligned vertically — misaligned barrels will bind when the gate closes. Hang the gate on the post-side hinges, then mount the gate-side hinge leaves.

Step 6: Adjust or Replace the Gate Latch

Once the gate is square and the hinges are solid, address the latch if it is no longer aligned with the strike.

For a latch that is close but not quite catching: Most gate latches have slotted mounting holes that allow 1/2 to 1 inch of vertical adjustment. Loosen the mounting screws, slide the latch to the correct position, and re-tighten.

For a strike that needs repositioning: If the gate is now higher than it was before repair, the strike (the bolt receiver on the post or gate frame) may need to be moved up. Remove the strike screws, fill the old holes with the toothpick method or wood filler, let dry, and mount the strike at the new position.

Self-closing and self-latching options: If the original latch was unreliable, this is a good opportunity to upgrade. Self-closing spring hinges automatically pull the gate closed. Self-latching latch sets automatically catch when the gate closes. For pool gates and other code-regulated applications, self-latching hardware is often required.

Step 7: Preventive Measures for Long-Term Gate Performance

A repaired gate stays fixed longer with a few preventive measures:

Seal the gate frame. Bare or degraded wood absorbs moisture, swells, and contributes to joint loosening and post lean. Apply exterior wood preservative or paint to all gate frame members, including end grain on cut ends.

Check hinge screws annually. Gate hinges take more wear and stress than fence hinges. During your annual fence inspection, check that all hinge screws are tight and that the hinge leaves show no bending.

Keep the gate frame off the ground. The bottom rail should clear the ground by at least an inch to prevent moisture absorption and rot. If the bottom rail contacts the ground at any point in the swing arc, trim back the ground material or adjust the hinge height.

Install a gate cane bolt for double gates. If you have two-leaf gates (a pair of gates that meet in the middle), install a cane bolt — a vertical rod that drops into the ground — on the passive leaf to stabilize it. A double gate with no cane bolt on the fixed leaf puts all the closing force stress on the latch and frame joints.

How to Build a Fence — full fence installation with proper gate post setting
How to Fix a Broken Fence Post — post repair and replacement when the hinge post is failing
Annual Home Maintenance Checklist — seasonal fence and gate inspection schedule

⏰ PT8H 💰 $10–$50 🔧 Pressure-treated lumber, Exterior screws or nails, Post hole digger, Concrete mix, Exterior wood sealer or stain

Diagnose the Real Problem
Before buying parts or making repairs, identify the actual source of the sag. Fence gate repairs fail repeatedly when the repair targets the symptom (gate drooping) instead of the cause (leaning post, failed hinges, racked frame).
Fix a Leaning Hinge Post
If the hinge post is leaning, this must be addressed before any gate repair.
Fix Stripped Hinge Screws
Stripped screw holes are one of the most common hinge problems and one of the easiest to fix.
Install an Anti-Sag Cable Kit
For a gate with a plumb post and solid hinges where the frame has racked, an anti-sag kit is the most efficient repair.
Replace or Upgrade the Hinges
If the existing hinges are bent, too small for the gate weight, or the mounting surfaces are too damaged to hold screws reliably, replace the hinges entirely.
Adjust or Replace the Gate Latch
Once the gate is square and the hinges are solid, address the latch if it is no longer aligned with the strike.

How to Fix a Sagging Fence Gate: Anti-Sag Kits, Hinge Adjustment, and Frame Repair (2026)

What You Need

Step 1: Diagnose the Real Problem

Step 2: Fix a Leaning Hinge Post

Step 3: Fix Stripped Hinge Screws

Step 4: Install an Anti-Sag Cable Kit

Step 5: Replace or Upgrade the Hinges

Step 6: Adjust or Replace the Gate Latch

Step 7: Preventive Measures for Long-Term Gate Performance

Free: 10-Point Home Maintenance Checklist

Save this for next time.

How to Fix a Sagging Fence Gate: Anti-Sag Kits, Hinge Adjustment, and Frame Repair (2026)

What You Need

Step 1: Diagnose the Real Problem

Step 2: Fix a Leaning Hinge Post

Step 3: Fix Stripped Hinge Screws

Step 4: Install an Anti-Sag Cable Kit

Step 5: Replace or Upgrade the Hinges

Step 6: Adjust or Replace the Gate Latch

Step 7: Preventive Measures for Long-Term Gate Performance

Related Reading

Free: 10-Point Home Maintenance Checklist

Save this for next time.