One of the most common questions homeowners ask when shopping for a pet door is simple: What size pet door does my dog need?

Choosing the correct size is extremely important. A door that’s too small can make it difficult or uncomfortable for your dog to use, while a door that’s too large may reduce your home’s energy efficiency and security.

Fortunately, selecting the right size is easier than most people think. With a few simple measurements and a basic understanding of how dogs move through pet doors, you can confidently choose the perfect fit.

Step 1: Measure Your Dog’s Height

The most important measurement when choosing a pet door is your dog’s shoulder height.

To measure this:

1. Have your dog stand naturally.
2. Measure from the ground up to the top of their shoulders (also called the withers).
3. Add 1–2 inches to this measurement.

This ensures your dog can comfortably walk through the door without crouching or rubbing their back against the flap.

Many pet owners mistakenly measure the dog’s head height, but this is unnecessary. Dogs naturally lower their heads slightly when passing through a pet door.

Step 2: Measure Your Dog’s Width

Next, measure the widest part of your dog’s body, typically across the chest or shoulders.

Add about 1–2 inches of extra space to ensure your dog can pass through easily without squeezing.

This is especially important for breeds with broad shoulders or thick fur.

Step 3: Consider Your Dog’s Growth

If you have a puppy or a young dog that’s still growing, it’s important to account for their future size.

Installing a door that only fits your dog today could require replacing it in the near future. Planning ahead can save time and money.

Many homeowners choose a size that accommodates the dog’s expected adult height and width.

Step 4: Think About Multiple Pets

If you have more than one pet, always size the door for the largest animal that will use it.

Smaller pets will have no problem using a larger opening, but larger dogs cannot comfortably use a door that’s too small.

Step 5: Balance Size With Efficiency

While it may be tempting to install an oversized pet door “just in case,” larger openings can affect insulation and weather sealing.

Choosing the correct size—not just the largest size—helps maintain your home’s comfort and energy efficiency.

High-quality pet doors are designed to provide a tight seal regardless of size, but proper sizing still plays an important role.

Built-to-Order Makes Sizing Easier

One of the advantages of built-to-order pet doors is the ability to match the opening to your pet’s exact needs.

Rather than choosing from only a few generic sizes, homeowners can select dimensions that provide the perfect balance of comfort, insulation, and performance.

This precision fit helps ensure your pet door works flawlessly for years to come.

A Better Fit Means Better Freedom

When properly sized, a pet door becomes second nature for your dog. They move through it comfortably, confidently, and safely.

By taking a few simple measurements and choosing a well-built door, you can provide your pet with convenient outdoor access while maintaining the comfort and security of your home.

The right size makes all the difference.