Extra Large Dog Door Size Chart: How to Measure for Large and XL Dogs

Fit an XL dog door by matching the usable flap opening to your dog’s widest measurement — chest or hips — then checking height against floor-to-withers, not breed or weight.

A dog that has to duck through a flap will eventually stop using it. The fix isn’t a bigger “large” label — it’s three numbers: the dog’s widest girth, the floor-to-withers height, and the rise (distance ground to flap bottom). Get those right and the size chart below does the rest.

Why Weight And Breed Labels Mislead You

Two doors both stamped “Large” can have flap openings that differ by nearly two inches in each direction. Weight is a secondary filter at best.

Compare the published specs below. The PetSafe generic large door lists 10¼″ × 16¼″ with a 100 lb capacity; the Endura Flap Large is 10″ × 19″ with a minimum listed weight of 20 lb and shoulder height up to 27″. Same “Large” label, genuinely different openings.

Breed references help only as a starting point. Mastiffs, Great Danes, and Saint Bernards commonly land in XXL territory — but individual dogs vary enough that measurement has to win.

Extra Large Dog Door Size Chart: Published Openings Compared

The table below pulls the actual usable flap dimensions from each manufacturer’s chart — not the frame or the cutout. Read across to find the opening that clears your dog’s measurements.

Notice that frame size and cutout size never appear as flap dimensions — and they’re always larger. Confusing the three is the single most common ordering mistake. The measurement guidance from Endura Flap spells out the rise calculation that the charts don’t show.

How Do You Measure A Dog For A Door Flap?

Measure the dog standing fully upright, then add clearance before you buy. Four steps cover it.

1. Height: Have the dog stand square on flat ground. Measure from the floor to the tallest point of the back — that may be the shoulders, mid-back, or tailbone depending on build.
2. Width: Measure across the widest part of the chest or hips. PetSafe’s chart recommends adding 1–2 inches to both width and height when sizing from its general chart.
3. Real-world width check: Build a temporary opening and coax the dog through it, then measure that gap. The flap needs to be at least that wide.

When your numbers land between two PetSafe sizes, take the larger one. For a multi-pet home, size the opening for the biggest dog while keeping the rise low for the smallest — a high rise is rough on short-legged, senior, or injured dogs.

If you’d rather skip the guesswork, our roundup of the best xtra large dog door picks for big breeds compares tested options side by side.

What To Check Before You Cut The Hole

The opening size is only one of four dimensions — and cutting for the wrong one is expensive to undo.

• Frame vs. cutout: The wall hole is larger than the flap and varies by door material and mounting type. The PetSafe SmartDoor needs a 13.2″ × 19.1″ cutout in a non-metal door but 14.8″ × 21.5″ in metal.
• Model-specific specs only: The SmartDoor and Electronic Pet Door numbers apply to those named models, not every PetSafe door.
• Puppy growth: PetSafe’s chart advises accounting for future growth before you cut.
• Rise for seniors: An oversized flap with a tall step-over is worse than a slightly tight one for an older dog.

Write all four numbers down — flap, frame, cutout, rise — and match each one to the product page before the saw comes out.