Step 1: Pick the function

• Entry (keyed): Locks with a key from outside and a thumb turn inside. For exterior doors.
• Privacy: Locks with a push button or turn button inside, with an emergency release hole outside. For bedrooms and bathrooms.
• Passage: No lock. For closets, hallways and laundry rooms.
• Dummy: A fixed knob that doesn't turn or latch. For pantry doors, double closet doors, and doors held shut by a ball catch.

Tip: Replacing an entry knob and a deadbolt? Buy them as a keyed-alike set, so one key opens both.

Step 2: Measure before you buy

• Backset: the distance from the edge of the door to the center of the knob hole. It's almost always 2⅜ in. or 2¾ in. Most new latches adjust to fit either one, but check the box.
• Door thickness: most interior and exterior doors are 1⅝ in. to 1¾ in., which most knobs fit.
• Hole size: the standard knob hole is 2⅛ in. across. Older doors can be different.
• Take a photo of the old knob and latch before you take anything apart.

Check for a mortise lock: If the lock is a large rectangular box set into the edge of the door instead of a round latch, it's a mortise lock. A standard knob won't fit without modifying the door, so ask us or a locksmith first.

Step 3: Consider levers and finish

• Lever handles are easier to open with full hands, for kids, and for anyone with arthritis.
• Some levers are handed (made for left- or right-swinging doors). Most today are reversible. Check the package.
• Pick one finish for the whole house. It's what makes rooms look like they belong together.

Shop this step: Entry knobs · Privacy knobs · Passage knobs · Door levers · Deadbolts

Step 4: Gather your tools

• Phillips and flathead screwdrivers
• Tape measure
• Pencil
• Chisel (only if the latch or strike plate doesn't sit flush)
• Drill with small bits (for pilot holes)
• Wood glue and toothpicks (for stripped screw holes)

Step 5: Take off the inside knob

• Visible screws: remove the two screws on the inside rose (the round plate), then pull the knobs apart.
• No visible screws: look for a small slot or pin on the neck of the knob. Press it in with a small screwdriver while pulling the knob off. Then pry or twist off the round cover plate to reach the screws underneath.

Step 6: Pull the outside knob and the latch

• Pull the outside knob straight out. Wiggle it gently if it's stuck.
• Remove the two screws on the edge of the door holding the latch plate, and slide the latch out.
• Brush out any debris in the holes.

Step 7: Install the latch

• Set the latch to your backset if it's adjustable (most twist or slide between 2⅜ and 2¾ in.).
• Slide it into the edge hole with the slanted side facing the jamb, the direction the door closes. The slant is what lets it ride over the strike plate and snap shut.
• The latch plate should sit flush with the door edge. If it sits proud, deepen the recess slightly with a chisel.
• Screw it in and press the latch a few times to make sure it moves freely.

Easy check: Close the door partway and look. The flat side of the latch faces into the room the door swings toward, and the slanted side faces the frame.

Step 8: Install the outside knob

• On an entry or privacy knob, the keyed side or the release-hole side goes on the outside, or the hallway side.
• Feed the spindle and the two mounting posts through the holes in the latch.
• Turn the keyhole to the position the instructions show, and hold the knob flat against the door.

Step 9: Install the inside knob

• Line up the inside knob with the spindle and posts, and push it on.
• Drive the two long screws, alternating between them so the knob pulls in evenly.
• Snug them, but don't overtighten. Too tight makes the knob stiff and slow to spring back.

Tip: Test the knob and lock now, with the door open, before you close it. It's no fun being locked on the wrong side of your own door.

Step 10: Check the alignment

• Close the door slowly and watch the latch. It should drop into the center of the strike plate opening.
• Often the old strike plate lines up fine. If it does, keep it.
• If it doesn't, rub a little lipstick or chalk on the latch and close the door. The mark shows exactly where it hits.

Step 11: Adjust or replace the strike

• If it's off by a little, file the opening in the strike plate slightly larger.
• If it's off by more, move the plate. Trace it in the new spot, chisel the recess so it sits flush, and drill pilot holes before you drive the screws.
• Fill the old screw holes with glue and toothpicks, let it dry, then trim flush.

Exterior doors: Swap the short strike plate screws for 3 in. screws that reach the wall framing behind the jamb. Short screws are the weak point when someone tries to kick a door in.

Shop this step: Strike plates · Wood glue

Step 12: Run through the checklist

• Both knobs turn smoothly and spring back on their own.
• The latch fully extends and retracts.
• The key, thumb turn or push button locks and unlocks every time.
• The door closes and latches without slamming or pushing.
• All screws are snug.

Common problems

• Knob is loose: tighten the two mounting screws evenly. If they keep loosening, the posts may not be lined up through the latch. Take it off and reseat it.
• Knob is stiff or won't spring back: loosen the mounting screws a quarter turn. Overtightened screws are the usual cause.
• Latch won't catch: the strike plate is off. See Step 11. If the whole door has dropped, tighten the top hinge screws first.
• Key is hard to turn: puff a little graphite lubricant into the keyhole. Skip oil and spray lubricants, which collect dust and gum up the pins.
• Stripped screw holes: glue and toothpicks, or a slightly longer screw.

Shop this step: Door hinges