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How to replace a door lock

A short, no-nonsense walkthrough — the steps, the gotchas, and answers to the usual questions.

⏱ 20–40 minutes ◆ Easy

Replacing a door lock improves security after a move or a lost key, and it is a straightforward job with a screwdriver. This shows how to remove the old lockset and fit a new deadbolt or knob so it operates smoothly.

What you'll need

  • Replacement lock or deadbolt
  • Screwdriver
  • Tape measure
  • Pencil
  • Chisel (if adjusting the strike plate)

Step by step

  1. Measure the existing lockNote the backset (distance from the door edge to the center of the hole) and the hole diameter. Buying a lock that matches avoids drilling new holes.
  2. Remove the interior sideUnscrew the two screws on the inside plate of the knob or deadbolt. Keep the screws together so you do not lose them.
  3. Pull out the hardware and latchSeparate the two halves of the lock and slide them out of the door. Then unscrew the latch or bolt plate on the door edge and remove it.
  4. Insert the new latchSlide the new latch into the edge hole with the beveled side facing the door frame, and screw its plate in place.
  5. Fit the new lock halvesLine up the exterior and interior pieces so the tailpiece or spindle passes through the latch, then join them and drive in the connecting screws evenly.
  6. Test and adjust the strikeClose the door and turn the lock. If the bolt does not seat cleanly, adjust the strike plate on the frame, chiseling slightly if needed.

Handy tips

  • Take the old lock to the store or note its measurements so the replacement fits the existing holes.
  • Buy knobs and deadbolts keyed alike so one key works both.
  • A little graphite or dry lubricant in the keyway keeps the lock turning smoothly.

Heads up

  • Do not fully tighten one screw before the other; tighten evenly so the lock is not pulled crooked and binding.

FAQ

What is a backset and why does it matter?

The backset is the distance from the door edge to the center of the bore hole, usually 2 3/8 or 2 3/4 inches. Matching it ensures the new lock fits your door.

Can I rekey instead of replacing the whole lock?

Often yes. If the lock works well, a locksmith or a rekey kit can change it to a new key without a full replacement.

Why won't my new deadbolt line up with the frame?

The strike plate hole may need adjusting. Reposition the strike plate or enlarge its opening slightly so the bolt slides in fully.