Stoppers, Sash Locks or Wedges? Best Window Locks for Home Security and Toddlers

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The best window locks for home security do two jobs at once: they keep an intruder from sliding a window open, and they stop a toddler from pushing it wide enough to fall through. The right type depends on the window. Sliding windows take a clamp-on track stopper, single- and double-hung windows use a sash lock, and a soft wedge can limit how far either kind opens.

We compared seven locks in stock and sold by Amazon.com or the brand’s own store: three Prime-Line products (an aluminum track lock, a vinyl-window clamp and a replacement sash lock), Toddleroo wedge locks, two key-tightened stoppers from HYIEOU and STERGDE, and a Shop Square 10-pack. Every pick fell in our lowest price tier.

One rule covers all of them. A bedroom window may be someone’s way out in a fire, so whatever you install has to come off fast from the inside.

Our Top Window Locks For Home Security Picks at a Glance

Price key: $ under $50 · $$ $50–$100 · $$$ $100–$175 · $$$$ $175+. Prices change often; check Amazon for today’s price.

1. Prime-Line U 9819 Sliding Window Lock (4-Pack): Best Overall Sliding Window Lock

Prime-Line’s U 9819 is the simplest kind of window lock: a small aluminum block that clamps onto the track of a horizontal sliding window. With the lock tightened behind the moving sash, the window can’t slide past it, whether the window is fully closed or open a few inches.

Installation takes seconds. You set the lock on the rail where you want the window to stop and turn the thumb screw until it bites into the track. No drill, no tools and no permanent changes are involved, so you can move it later or take it with you when you move. Prime-Line says it secures windows in closed or ventilated positions, which lets you leave a gap for air without leaving the window free to open all the way.

Fit is the one thing to check. The listing says it’s designed for sliding window rails up to 1/8 inch wide and asks you to review the line drawing and rail dimensions before ordering. It’s aluminum with a natural finish, and each pack holds four locks. The warranty field covers manufacturing defects for one year, and the specs list a weight of 0.14 pounds.

It suits apartments and older homes with aluminum sliders, where a couple of dollars per window adds a second stop behind the latch.

Why we like it

• Tool-free install
• Sets a ventilation gap
• Four per pack

Watch out for

Measure the rail first; anything wider than 1/8 inch, including most vinyl frames, needs a different lock.

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2. Prime-Line U 9809 Vinyl Window Lock (2-Pack): Best Lock for Vinyl Sliding Windows

Prime-Line’s U 9809, sold under its Defender Security name, is a clamp-on lock made for vinyl windows. Vinyl frames tend to have thicker, softer rails than aluminum ones, and this lock’s adjustable jaw is built to grip them.

You hand-tighten the jaw onto the window rail, then flip the cam-style lever to lock it in place, a vise-like grip that Prime-Line says needs no tools, drilling or permanent changes. Like any track stopper, it can sit right against the closed sash or a few inches back to allow controlled ventilation on a mild day.

The listing says the jaw fits vinyl frame rail thicknesses from 1/16 inch up to 1/2 inch, and that the lock works on horizontal sliding vinyl windows and many single-hung vinyl windows. Construction is diecast with a white painted finish that blends with most vinyl frames. Prime-Line asks you to verify rail thickness and window compatibility before ordering. Each pack holds two locks, the warranty field covers manufacturing defects for one year, and the specs list 0.28 pounds.

It suits homeowners with vinyl replacement windows who found that thin-rail aluminum stoppers won’t fit, and anyone who wants a lock that matches a white vinyl frame instead of bare metal.

Why we like it

• Wide 1/16–1/2 in jaw range
• Cam lever, no tools
• White finish suits vinyl

Watch out for

Prime-Line says it’s for vinyl windows only, so aluminum and wood frames need a different lock.

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3. Prime-Line F 2588 Vinyl Window Sash Lock: Best Window Sash Lock

Prime-Line’s F 2588 is a replacement for the lock that came with your window. On single- and double-hung windows, the sash lock sits where the two sashes meet in the middle; the lever turns a cam on the lower sash that hooks into a keeper on the upper one.

When the old lock gets loose, cracked or goes missing, the window can be lifted from outside even when it looks closed. Swapping in this unit restores that basic lock. Prime-Line says the cam-action design pulls the sash and keeper together for a tighter seal, which it says improves insulation and reduces drafts as well.

The listing is specific about fit: it’s for vinyl window systems with flush-mounted meeting rails and 2-1/16-inch mounting hole centers on both the lock and the keeper, and it’s not universal. You get one lock, one keeper and the mounting fasteners in a diecast zinc body with a white painted finish. The warranty field covers manufacturing defects for one year, and the specs list 0.18 pounds.

It suits homeowners with hung vinyl windows whose original lock has failed, especially when the hole spacing matches and you’d rather fix the original latch than add a second device to the frame.

Why we like it

• Restores the factory-style lock
• Tightens the sash seal
• Lock and keeper included

Watch out for

Measure the screw-hole spacing on your old lock before ordering; at anything other than 2-1/16 inches, it won’t line up.

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4. Toddleroo by North States Window & Door Wedge Locks (4-Pack): Best Window Locks for Kids

Toddleroo by North States makes these wedge locks for childproofing rather than burglar-proofing. Each one is a white wedge that attaches to the window or door frame and blocks the sash from opening past a set point, so a curious toddler can’t push the window wide.

Installation uses hook and loop, with no tools, screws or nails, and the listing says the locks won’t damage your windows or sliding doors. Because the wedge sets how high a window can rise or how far a slider can open, you can still crack a window for air while keeping the gap small. North States says they can be quickly removed in an emergency, which matters on bedroom windows.

The listing names double-hung windows, horizontal sliding windows and sliding doors, and the four-pack is meant to cover several of them at once. North States says the locks limit the height a window or door can open and protect toddlers from falls, but it doesn’t give the gap in inches, so measure the opening yourself after you install them. The specs list a weight of 0.18 pounds, and the warranty field is empty.

It suits parents of toddlers and young children who want to cap window openings in nurseries and playrooms without drilling.

Why we like it

• No drilling
• Covers windows and sliders
• Quick to remove

Watch out for

Measure the opening with the wedge in place and adjust until it’s no more than 4 inches.

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5. HYIEOU Sliding Window Locks With Key (2 Sets): Best Keyed Window Lock

HYIEOU’s window locks clamp onto a sliding window track like other stoppers, and the title sells them “with Key.” The listing describes tightening a screw and includes a key, rather than the thumb-turn knob on the Prime-Line or Shop Square locks, which helps if you’re worried about a child, a pet or someone reaching in through an open gap. Check the photos to see how the screw head is turned.

Day to day, you set the lock on the track where you want the window to stop: tight against the sash to keep it shut, or farther back to leave a ventilation gap. HYIEOU says this lets you lock windows fully when closed, or at any position that leaves a gap for air while preventing wide openings. The lock can go on the side track or the center track, and a vertical key handles center-track installs.

Fit is listed precisely: the track must be taller than 0.48 inch and narrower than 0.62 inch, so measure before ordering. Installation takes three steps and no drilling: place the lock, insert the plastic washer that protects the track from scratches, then tighten the screw. The locks are aluminum alloy, the listing names both vertical and horizontal sliding windows, and the specs list 0.24 pounds for two sets.

It suits renters and parents with a couple of sliding windows who want a stopper without a finger knob, as long as an adult keeps the key nearby.

Why we like it

• No thumb-turn knob described
• Vertical or horizontal windows
• Track-protecting washer

Watch out for

Store the key near the window, out of a child’s reach, so an adult can release it quickly in a fire.

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6. STERGDE Adjustable Window Security Locks (4 Sets): Best Window Stoppers With Hex Keys

STERGDE’s adjustable window locks are track stoppers for sliding windows and sliding doors, built around a separate key. Each lock tightens with a hex key, so it can’t be loosened with fingers, and the window can be held closed or partly open to let air in.

Day to day, you place a lock on the inside or center track where you want the sash to stop, slip in the protective gasket and tighten the screw. STERGDE says no drilling or extra tools are needed, and you can reposition the locks with the vertical key or hex key whenever you want a different gap.

The listing calls out a “window lock and key separation design” meant to keep others from unlocking the window at will, thickened aluminum alloy, two fixed holes for a stronger hold, and a widened lock body that blocks more of the track when the window is open. Fit depends on the track: STERGDE asks for a height greater than 0.48 inch and a width under 0.61 inch. The pack includes four locks, four hex keys, four protective gaskets and one vertical key for center-track mounting. STERGDE names pets and trespassers as the two concerns it addresses.

It suits homes with several sliders that are often left open a few inches for air.

Why we like it

• Four locks per pack
• Hand-proof hex screw
• Track-protecting gaskets

Watch out for

Hang a hex key near each window you might need to escape through, high enough that small children can’t reach it.

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7. Shop Square Sliding Window Locks (10-Pack): Best Window Lock Multi-Pack

Shop Square’s 10-pack covers a lot of windows for one order. Each lock is an aluminum stopper that clamps to a sliding track with a thumb screw, so the sash can’t move past it, whether the window is shut or open a few inches.

Installation needs no tools. You set the lock on the track and turn the thumb screws until it holds. A vinyl lining inside the clamp keeps it from scratching the frame and, according to Shop Square, adds gripping power. The listing pitches the same locks for patio doors and sliding glass doors as well as horizontal and vertical sliding windows.

Fit is flexible for a stopper: Shop Square says the locks fit sliding doors and windows up to 3/16 inch wide with the detachable rubber insert, or up to 3/8 inch without it. The brand suggests using them to lock in a vertical window air conditioner or window fan, as a camper lock replacement, or as part of babyproofing. Model LLTR10 is listed as heavy-duty aluminum.

It suits homeowners who want the same lock on every slider and patio door in the house, landlords outfitting several units at once, and anyone securing a window AC unit against being pushed in.

Why we like it

• Ten per pack
• Wider track range
• Frame-friendly lining

Watch out for

Thumb screws keep them quick to remove in a fire, but they won’t stop an older child who figures them out.

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How We Chose the Best Window Locks

We only considered locks that were in stock and sold by Amazon.com or the brand’s own store, then compared what each listing says:

• Window type: horizontal sliders, vertical sliders, and single- or double-hung windows.
• Frame fit: rail width or thickness, track height, hole spacing, and whether the lock is for vinyl or aluminum.
• Release: thumb screw, cam lever, hook-and-loop wedge or key, and how quickly an adult can remove it.
• Ventilation: whether it can hold a window partly open.
• Seller and warranty: the seller and what the warranty field actually says.

Every qualifying pick fell in our lowest price tier, so we chose by window type rather than price. We also skipped the door-bar products covered in our door security bar guide.

Window Lock Buying Guide

Best Sliding Window Locks

Track stoppers clamp to the rail behind the moving sash. Thumb-screw models, like the Prime-Line U 9819 and Shop Square, are fastest to set and remove. STERGDE’s locks tighten with a hex key, so fingers alone can’t loosen them, and HYIEOU’s are sold with a key and describe no thumb knob. All of them can hold a window shut or open a few inches.

Vinyl vs. Aluminum Frames

Check the listed fit before anything else. The Prime-Line U 9819 fits rails up to 1/8 inch, Shop Square up to 3/16 inch with its insert (3/8 inch without), and the Prime-Line U 9809 grips vinyl rails from 1/16 to 1/2 inch but is for vinyl only. HYIEOU and STERGDE give track limits instead: taller than 0.48 inch and narrower than 0.62 or 0.61 inch.

Best Window Sash Lock

On single- and double-hung windows, start by making sure the built-in sash lock works. If it’s loose or missing, a replacement such as the Prime-Line F 2588 restores it, provided your hole centers measure 2-1/16 inches and the meeting rails are flush.

Best Window Stoppers and Keyed Window Locks

A stopper set a few inches from the closed position lets air in while blocking a wide opening. Keyed stoppers add a layer against small hands, but the key becomes part of your escape plan. Keep it near the window and out of a child’s reach, and make sure every adult knows where it is.

Best Window Locks for Kids

Toddleroo’s wedge locks attach with hook and loop and limit how far a double-hung or sliding window opens. Any of the track stoppers here can do the same job on a slider if you set them so the gap stays small. For stairs and doorways, see our baby gate guide.

Window Falls and Fire Escape: Locks That Open Fast

Window locks protect children only when they limit the opening. CHOC’s home and window safety guide says window screens are no match for even a young child’s weight and that small children can squeeze through openings as narrow as 4 inches. It advises removable window locks or guards that limit an opening to no more than 4 inches, can be removed quickly by adults in an emergency, and keeping beds, bookcases, chairs and other furniture away from windows. HealthyChildren.org’s home safety page likewise says a screen is not strong enough to prevent a fall and suggests opening windows from the top when possible.

That emergency release matters because a bedroom window may be a fire exit. Ready.gov’s home fires page says to find two ways out of each room and to make sure windows aren’t stuck, screens can be taken out quickly and security bars can be properly opened. Safe Kids Worldwide’s falls page advises an emergency release device on window guards above the first floor in case of fire. Practice removing your window locks during fire drills, and if a second-floor window is the backup exit, pair it with a fire escape ladder.

Locks are one layer of home security. Our Ohio homeowners insurance guide covers how a policy is generally structured. Some insurers consider security devices when pricing coverage, but that varies, so ask your agent rather than assuming a discount.

Frequently Asked Questions

What are the best window locks for home security on sliding windows?

A track stopper behind the moving sash. The Prime-Line U 9819 fits rails up to 1/8 inch with a thumb screw; the STERGDE stoppers tighten with a hex key, and HYIEOU’s come with a key and no thumb knob. Measure your track before you buy.

What are the best window locks for kids?

Locks that limit the opening and come off quickly for adults. CHOC advises limiting window openings to no more than 4 inches. Toddleroo’s wedge locks cap how far double-hung and sliding windows open, and track stoppers can do the same on sliders.

Do window screens stop a child from falling?

No. HealthyChildren.org says a screen is not strong enough to prevent a fall, and CHOC says screens are no match for even a young child’s weight. Use a stopper or guard and keep furniture away from windows.

Is a keyed window lock safe in a bedroom?

Only if adults can release it fast. Ready.gov says to make sure windows aren’t stuck and security bars can be properly opened as part of your escape plan. Keep the key next to the window, out of a child’s reach, and practice using it.

What is the best window sash lock replacement?

For vinyl single- or double-hung windows with flush meeting rails and 2-1/16-inch hole centers, the Prime-Line F 2588 replaces a worn or missing lock and pulls the sashes together with a cam action, per the listing.

The Bottom Line

For most sliding windows, the Prime-Line U 9819 four-pack is the best window lock for home security: tool-free, adjustable for ventilation and the best seller here. Vinyl sliders need the Prime-Line U 9809, broken sash locks call for the Prime-Line F 2588, and the Toddleroo wedges cap openings for toddlers. The key-equipped STERGDE and HYIEOU stoppers are harder for small hands to undo, and the Shop Square 10-pack covers a whole house. Whatever you choose, make sure every adult can open each bedroom window fast.

Adding locks and wondering how your policy handles break-ins or window damage? Call Jeff Smith’s State Farm office at (740) 354-7747 or request a free coverage review.