Replacing a Door Lock
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Replacing a door lock is one of the fastest home improvement projects. If you are swapping an existing lock for a new one of the same type, it is a screwdriver and 15 minutes. If the new lock has different dimensions than the old one, you may need to enlarge the bore hole, which adds a drill and a hole saw to the list.
Cost Breakdown
Removal
Phillips head removes the old lock. Most locks use #2 Phillips screws on the interior plate.
Installation
Installs the new lock. Same Phillips head.
Measure the backset (distance from door edge to center of hole) if the new lock does not match the old one. Standard is 2-3/8" or 2-3/4".
Only needed if the new lock bore is larger than the existing hole. A 2-1/8" hole saw is the standard size for deadbolts.
Enlarges the latch plate mortise if the new plate is a different size than the old one.
Consumables and Supplies
These get used up during the project. Always buy these new.
- New lock set (knob, deadbolt, or both) Measure your backset before buying: 2-3/8" or 2-3/4"
- Longer screws for the strike plate The screws that come with most locks are 3/4". Replace with 3" screws that reach the door frame stud for security.
Safety Gear
- Safety glasses (if drilling)
Before You Buy Anything
Check if your neighbors already have the tools you need. Borrowing saves money, saves storage space, and keeps tools in use instead of collecting dust.
See how FriendsWithTools worksCommon Questions
How do I know what size lock to buy?
Measure two things: the backset (distance from the edge of the door to the center of the existing hole, usually 2-3/8" or 2-3/4") and the door thickness (standard is 1-3/8" for interior, 1-3/4" for exterior). Most new locks are adjustable for both common backsets. The bore hole is almost always 2-1/8" for both deadbolts and knob sets.
Should I replace the strike plate screws?
Yes. The short screws that come with most lock sets only reach the door jamb, which is soft pine. Replace them with 3-inch screws that reach the wall stud behind the jamb. This makes the lock significantly more resistant to kick-in attacks. A $2 upgrade that meaningfully improves security.