Dog doors are available in multiple sizes to suit all types of dogs. With dog sizes ranging from toy breeds to extra large dogs, there is not a one-size-fits-all dog approach.
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27/10/25
Dog Door Sizes
Dog doors are available in multiple sizes to suit all types of dogs. With dog sizes ranging from toy breeds to extra large dogs, there is not a one-size-fits-all dog approach. Dog doors are typically available in three different sizes- small, medium and large that can be fitted into timber, glass, screen doors and walls. To understand the right size door for your dog, we will guide you through the different size dog doors, what to consider when choosing a dog door size, and how to measure your dog to make sure you get the right sized dog door.
LARGE DOG DOOR

MEDIUM DOG DOOR

SMALL DOG DOOR

What Sizes Do Dog Doors Come In?
Dog doors come in three different sizes – small, medium and large. However, dog doors for glass are available in small, intermediate, medium and large. When considering dog door size, the most important size for dogs is the dog door opening, or the flap that the dog will walk through. The exterior dimensions will be larger as the frame the dog door flap is inserted into.
Small dog door
Small dog doors generally have an opening of 240mm x 190mm and are suitable for breeds up to 9kg like Chihuahuas and Dachshunds, as well as cats. The Dogwalk Glass Fitting Door is specifically designed for very small dogs that weigh under 6kg and has an opening of 195mm x 185mm.

Intermediate dog door
An intermediate dog door from Sydney Pet Doors has an opening of 240mm x 215mm, ideal for dogs between 7kg and 13kg. Intermediate dog doors are perfect for breeds like Fox Terriers and King Charles Cavaliers.

Medium dog door
Medium dog doors typically have an opening size of 225mm X 305mm and are ideal for breeds like Spoodles, Maltese Terriers and Border Collies from 10kg to 22kg.

Large dog door
Large dog doors are perfect for dogs over 22kg like Labradors, German Shepherds and Golden Retrievers. The opening of a large dog door will measure on average 295mm x 425mm.

How To Measure Your Dog for A Dog Door
When working out the right sized dog door for your dog, you are trying to decipher the right sized opening (flap) that the dog will need to get through comfortably. To do this, you need to measure your dog, taking into account its height and width.
Follow these steps to measure your dog for a dog door:
- Measure your dog’s height from the tallest point of the dog’s back to the ground in cms. The tops of the dog door flap should be around 3cm higher than the tallest point on the dog’s back.
- Measure the dog’s width from shoulder to shoulder across the chest in cms, at its widest points. The widest part of the dog door opening should be about 5cm wider than the widest part of the dog.

Other Considerations When Choosing a Dog Door Size
While the dog’s height and width are imperative measurements to take into account for the right dog door size, there are other considerations you need to think about. All dog breeds are different. Some types of dogs are stronger and need a more sturdy dog door. Others might be older and need a dog door that is easy to access. Consider these factors when choosing a dog door size.
- Breed and size: The breed and size of the dog is essential when choosing the right dog door size. A dog needs to be able to fit through the dog door comfortably so it will need to accommodate its size. Dogs also need to be able to step over the dog door lip to walk through the opening as well so a dog breed with short legs will also need to be accounted for when taking into account step over height.
- Age and potential growth: If you have a puppy then take into account how big it will grow to adult size when choosing a dog door. Select the dog door size based on the dog’s adult size. A small dog will usually reach full size by between 6 and 12 months, while large dogs are usually full size within 2 years. An older dog may be less mobile and require a dog door that is larger and easier to get through.
- Multiple pets: If choosing a dog door for multiple pets of different sizes, make sure the dog door is sized for the largest dog. The step over height, however, will need to be chosen for the smallest pet though.
- Door type and installation: The dog door type affects the installation methods which can constrain the size dog door you can install. Dog doors in glass sliding doors tend to have a fixed step over height which will need to be considered for a smaller breed or a dog with mobility issues. The type of dog door and installation may also affect the panel width. A dog door installed in a wall may not be as wide as a different dog door and unable to accommodate a large dog, for example.
Dog doors come in a large variety of sizes because there are a large variety of dog types and breeds. Choosing the right dog door size is important for your dog’s comfort, long term health and safety. A dog door that is too large may hinder small dogs from being able to walk through. If a dog door is too small, the dog can suffer injuries or physical strain, or simply be unable to walk through. Sydney Pet Doors has a wide range of dog doors in all shapes and sizes to suit every breed and type of dog. Contact them today to find out more and how to choose the right sized dog door for your precious canine.
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