That 2 a.m. scratching at the bedroom door is not a personality quirk. It’s a design problem. If your cat needs access to a litter room, laundry room, or tucked-away feeding area, learning how to put a cat door in an interior door can solve a daily annoyance without turning your home into a pet obstacle course.

The good news is this is usually a very manageable project. The less-good news is that not every cat door works the same way, and not every interior door should be cut the same way. If you want a result that looks clean, works quietly, and doesn’t make your door look like a rushed weekend mistake, placement and door type matter just as much as the cut itself.

Before You Put a Cat Door in an Interior Door

Start with the actual problem you’re trying to fix. Some homeowners want to hide the litter box behind a closed door. Others need to keep a dog out of the cat’s room. Some just want to stop the constant scratching, meowing, and dramatic pawing every time a door closes.

That goal should shape the kind of cat door you choose. A standard flap door is familiar, but it changes the look of the door and can swing, click, or let smells and sound travel more easily. A corner-mounted interior cat door is a different approach. It preserves more of the door’s appearance, keeps the opening more discreet, and often makes more sense for homes where aesthetics matter and the door is inside the house rather than leading outdoors.

You’ll also need to confirm whether the door is hollow core or solid core. Most interior doors in American homes are hollow core, which makes cutting easier but also means you need to be more thoughtful about the edges and support. Solid core doors feel sturdier and offer a little more forgiveness structurally, but they take more effort to cut cleanly.

Tools and Materials You’ll Likely Need

For most installations, you need a drill, a jigsaw, a pencil, a tape measure, painter’s tape, and sandpaper. Depending on the kit, you may also need a screwdriver and the included hardware or template.

The template matters more than people expect. If your cat door system includes one, use it. Freehanding the opening is how you end up with crooked corners, gaps, and a finished result that looks homemade in the wrong way.

Before cutting, remove the door from its hinges if the instructions recommend it. Some people try to cut with the door standing in place to save time. That usually makes the job harder, not easier. A flat, stable surface gives you better control and a cleaner cut.

How to Put a Cat Door in an Interior Door the Right Way

First, measure your cat. Not in a fussy, tailor-made way - just enough to know the opening will be comfortable. You want your cat to move through without crouching awkwardly or bumping the frame. If you have more than one cat, size for the largest one who will use it.

Next, decide on the location. For a traditional flap, this is often lower and centered on the door. For a corner-mounted interior system, placement will follow the kit’s orientation and hinge design. This is where people make one of the biggest mistakes: they choose placement based only on appearance and ignore door swing, trim clearance, and room layout.

If the door opens toward a wall, nearby cabinet, or litter enclosure, check that the installed opening will still function properly when the door moves. If your product is designed by door swing orientation, get that detail right before you cut anything. Left-hand and right-hand setups are not interchangeable just because they look close in the box.

Once placement is confirmed, tape the template in place and trace the cut line carefully. Painter’s tape can help reduce splintering and gives you a clearer visual edge. Drill starter holes where needed, then cut slowly with the jigsaw. Slow is clean. Rushing is how you chip veneer, wander off the line, or crack a lightweight hollow core skin.

After the opening is cut, sand the edges lightly. You’re not refinishing furniture here. You just want smooth edges so the frame or insert sits properly. Then install the cat door components according to the product instructions, tightening hardware evenly rather than cranking down one side at a time.

Hollow Core vs. Solid Core Doors

If you’re installing into a hollow core interior door, expect a thinner outer shell with empty space inside. That’s normal. It doesn’t mean you can’t install a cat door there. It just means the product should be designed to work with that structure and provide a finished, stable result once mounted.

A poorly designed insert can leave hollow core doors looking flimsy around the cutout. A better-designed system accounts for the door’s construction and secures cleanly without making the panel look caved in or unfinished.

Solid core doors are denser, quieter, and often found on bedrooms, offices, or upgraded interiors. They cut more slowly, but they also tend to feel more substantial once the install is complete. If appearance and sound control matter, solid core can be a great candidate.

Getting the Height and Position Right

Cats don’t need a huge opening, but they do need a natural path. The bottom of the opening should be low enough that your cat can pass through comfortably without hopping or hesitating. For most interior setups, lower placement is best.

That said, there are practical exceptions. If the goal is to keep a dog out, the design of the opening matters more than just height. Some interior cat door systems use shape and corner placement to give cats access while making it harder for larger pets to follow. That’s a much smarter strategy than simply mounting a basic flap slightly higher and hoping your dog gives up.

This is also where visual discretion comes into play. A centered flap announces itself from across the room. A cleaner, more integrated corner design can be far less noticeable, which matters if the door sits in a hallway, bedroom, or main living area.

Common Mistakes to Avoid

The first mistake is treating all cat doors like they’re interchangeable. They’re not. An outdoor pet flap and an interior access door solve different problems.

The second is ignoring the way the door swings. If you install the wrong orientation, you can end up with awkward clearance, limited access, or a setup that never feels quite right in daily use.

The third is cutting before checking both sides of the door. Interior doors are part of a room, not just a panel. Look for baseboards, wall returns, nearby furniture, litter boxes, and anything else that could interfere with entry or exit.

The fourth is focusing only on the cat and not the household. If your real issue is odor control, visual clutter, or keeping dogs out of the litter box, choose a system designed around that. A random flap may give the cat access, but it may not actually solve the part of the problem that’s driving you crazy.

Is This a DIY Job or Better Left to a Pro?

For many homeowners, this is a realistic DIY project. If you can measure accurately, follow a template, and handle a jigsaw with patience, you can probably install a cat door in an interior door yourself.

If you rent, pause before cutting. You may need written approval, or you may want to install the door on a replacement slab so you can swap the original back later. If the door is expensive, custom-painted, or part of a more formal interior, hiring a handyman may be worth it for peace of mind alone.

A purpose-built kit also changes the equation. Products designed specifically for interior residential doors tend to be more straightforward to install and produce a cleaner result than generic pet doors adapted for indoor use. That’s the difference between a fix that feels smart and one that looks like you lost a bet.

One example is Kitty Korner, which was built specifically around the realities of interior doors, door swing orientation, and the very real household politics of cats wanting access while dogs absolutely should not get it.

What to Expect After Installation

Most cats figure it out quickly, especially if the new opening leads to food, privacy, or a familiar litter area. A few need encouragement. Leave the destination room comfortable and appealing, and give your cat time to investigate on their own terms.

You may also notice something else right away: your home works better. The door can stay closed, the litter box can stay hidden, and everyone gets a little more peace. That’s really the point. This isn’t about adding a novelty feature for your pet. It’s about making your rooms function the way they should without forcing your cat to wait for a human doorman.

A well-installed interior cat door should feel like it was always supposed to be there. Quiet, useful, and not ugly. That’s a pretty good standard for any home upgrade.