Best Dog Flaps UK: Doors for Small to Giant Dogs

How we chose these dog flaps: every flap is sold for dogs, each was in stock on its UK product page on 7 October 2026, and the sizes, thickness limits and locking details come from the makers. We have not fitted every model ourselves. These are manual flaps; if you want a flap that reads your dog’s microchip or opens on its own, see our automatic dog doors guide.

What Size Dog Flap Do You Need?

Measure your dog’s shoulder height, from the floor to the top of the shoulder blades, and its widest point across the chest. The flap opening should be a little taller than the shoulder height above the bottom of the flap, and wider than the chest, so your dog can walk through without crouching or squeezing. Dog Mate quotes shoulder heights directly, at up to 460 mm for the medium and 630 mm for the large, which makes choosing easy.

Fit height matters as much as size. The bottom of the flap should sit at roughly a third of your dog’s shoulder height above the floor, so it steps through rather than jumps. For a growing puppy, buy for the adult size and fit it slightly lower at first.

Which Dog Flap Works in a UPVC, Glass or Wall Fitting?

Most flaps fit wooden and UPVC doors, but check the thickness range. The Dog Mate flaps are self-lining to 50 mm, so they cover the cut edges of most doors and thin panels. A UPVC door is usually fitted through a replacement panel rather than cut directly, and a glazier can cut glass to take a flap. For walls, you need a tunnel or lining kit to bridge the cavity, and the PetSafe and Dog Mate flaps can both be used in walls with the right extension. Cheaper flaps such as the two-way clear flap need a separate tunnel for thick doors.

How Do Dog Flaps Keep Out Draughts and Strangers?

Draughts are the main complaint about dog flaps. A magnetic strip along the bottom, like those on the Lessmon and tekrabea doors, pulls the flap shut after each use, and a double flap, as on the Zerodis and Bluethy doors, traps a layer of air. The Ferplast Swing 11 adds a small wind stopper.

Security is about the closing panel. Every flap here can be locked, but a solid metal or rigid panel, like the PAWISE metal rear panel, is stronger than a thin slide. A large dog flap can be big enough for a small person, so lock it when you go out and talk to your insurer if you fit one in an outside door.

How Do These Dog Flaps Compare?

How Do You Fit and Train a Dog to Use a Flap?

Use the template supplied, and check twice before you cut. Then teach your dog in short, happy sessions.

1. Mark the flap height from your dog’s shoulder measurement and cut using the maker’s template.
2. Fit the frame and lining, then tape the flap open for the first day or two.
3. Call your dog through with treats from the other side, then let the flap rest on its back as it walks through.
4. Close the flap fully only when your dog pushes through confidently, and lock it at night.

A dog with free access to a garden needs secure fencing. A flap is also handy alongside a dog playpen outside.

Frequently Asked Questions

Last reviewed: 23 October 2026.