Rekey vs Replace: Which Your Locks Actually Need

The one-sentence rule

If the hardware is sound and you only need old keys to stop working, rekey it; if the hardware is worn, damaged, low quality, or below the security level you want, replace it.

What rekeying actually does

A locksmith removes the cylinder, swaps the pin stack to match a new key cut, and every old key becomes useless. The lock body, latch, and trim stay put. It costs $20 to $35 per cylinder plus a service call, takes minutes per lock, and can also put every exterior door on one key if the brands share a keyway. Our guide to pin tumbler mechanisms shows exactly what is happening inside.

Rekey when

• You move into a purchased home. You have no idea how many copies exist. Rekeying every exterior door on day one is the single best $150 in home security.
• A key is lost or unreturned after a roommate, contractor, cleaner, or ex had access.
• You want one key for everything and your locks share a keyway.
• A rental turns over and the locks themselves are decent. Many states and cities expect or require rekeying between tenants.

Replace when

• The lock is worn. Sticky keys, sagging latches, and loose handles are mechanical problems a rekey cannot fix.
• There was a break-in or attempt. Even if it looks fine, internal damage is common. Upgrade the strike plate and screws at the same time; our home security guides cover door reinforcement.
• The hardware is builder-grade junk and you care about the door it protects. Moving from a bargain cylinder to a Grade 1 or 2 deadbolt is a real security change, not a cosmetic one. See the ratings guides for what the grades mean.
• You are switching form factors: adding a deadbolt where there is none, going keypad or smart, or matching new door hardware finishes.

The middle path: new cylinder, same lock

Quality mortise and commercial hardware often accepts a fresh cylinder or an interchangeable core. You keep expensive, sound hardware and replace only the part that defines the key. This is standard practice in offices and a smart option for high-end residential hardware.

Do the math

Whole-house rekey: usually $100 to $200 all-in. Whole-house replacement with mid-grade deadbolts: $400 to $900 with labor. If the answer is not obvious, run your situation through the rekey or replace tool, and when hiring, pick a shop from the directory and sanity-check the quote against the cost guide.