Measure the pet. Then plan the opening.

Start with a record, not a size label

“Large” is a label within a product range, not a measurement you can transfer between manufacturers. Before comparing products, make one dated record for each pet who will use the route. Record the units and repeat your observations on another occasion if the pet is moving or the result is uncertain. Do not hold a pet in an uncomfortable position to complete a worksheet.

Use a level floor and a relaxed standing posture. Keep the tape near the pet rather than wrapping it tightly around the body. Our worksheet stores shoulder height, widest body width and an observed comfortable step. These are notes for a fit conversation; the tool does not choose a model or calculate an installation cutout.

Keep three sets of dimensions separate

Pet measurements

The animal’s dimensions and your observations of how it moves.

Clear passage

The usable space the animal passes through in the selected product.

Installation dimensions

The manufacturer’s rough opening and outside frame dimensions for the exact configuration.

A passage dimension is not a cutting template. Likewise, the outside trim can look large while surrounding a smaller usable passage. Ask the supplier to identify each dimension in a current drawing before you order. Hale’s sizing chart publishes these as separate columns, which is a useful example of why the distinction matters. Read the manufacturer’s sizing guidance.

Record height, width and the threshold

Hale’s guidance considers shoulder height, width at the widest part of the pet and the step-over. For a shared opening it also calls attention to the tallest pet and the one needing the lowest step. Apply a selected manufacturer’s clearance requirements only after collecting the raw measurements; do not copy one brand’s allowance to every product.

Observe an ordinary, familiar threshold without asking the pet to jump or attempt a progressively higher obstacle. Write “unknown” if there is no comfortable step you can confidently record. A change in movement or apparent discomfort calls for veterinary advice before planning the route around it.

Measure the approach on both sides

Label your photos “inside” and “outside.” Record the floor and landing levels independently. A threshold that looks low from the kitchen may be a much larger step from the garden. Note the mat, floor finish, nearby furniture and whether the pet must turn immediately after passing through.

Keep growth and household changes visible in your notes. A puppy’s present measurements are not a forecast of adult dimensions. If the household includes a tall dog and a much smaller pet, a single average erases the very differences the installer needs to see.

Take this packet to the supplier

• One dated measurement record per pet, including uncertainty.
• Photos and floor levels on both sides, with units.
• The proposed route and any access restrictions.
• The exact model drawing showing passage, rough opening and outside frame.
• A written answer about the proposed mounting height and each pet’s access.

Use the worksheet summary as a starting point for that conversation. A successful calculation means the entries were summarized correctly; it is not a finding that an opening is comfortable, safe, compliant or suitable for your home.