What each one does
Rekeying changes the small pins inside the lock's cylinder so it answers to a new key. The old keys stop working the moment it is done. The lock body, the handle and the deadbolt stay on the door, which is why it is quick and costs a fraction of new hardware.
Replacing takes the lock off and fits a new one. It also gives new keys, but it changes the hardware itself: a stronger deadbolt, a different style, a smart lock, a lock of a brand that matches the rest of the house.
Rekey when
- You moved in and do not know who holds keys: the builder, the last owners, cleaners, a realtor's lockbox.
- A tenant, roommate or employee has left.
- Keys were lost or stolen and the locks themselves are fine.
- You want every door on one key and the locks are the same brand.
Replace when
- The lock is worn: the key is stiff, the knob is loose, the bolt drags. A new key in a tired lock is still a tired lock.
- It is a knob with no deadbolt behind it on an exterior door. The knob latch alone is not a lock worth keeping.
- It is a different brand whose keyway will never share your key. A Kwikset key never fits a Schlage cylinder, so the odd one out gets a new cylinder or lock.
- You want something the old lock cannot do: a higher grade, a restricted key that cannot be copied, a keypad or a smart lock.
- It was damaged in a break-in.
What the grades mean
Deadbolts sold in the US are graded to an ANSI/BHMA standard. Grade 1 is the toughest and is built for commercial use; Grade 2 is a solid residential standard; Grade 3 is the minimum. The grade comes from cycle and strength tests, not from the packaging. For an exterior door, Grade 2 is a sensible floor and Grade 1 is worth it on a door that is out of sight. Our deadbolt page explains why the strike and screws matter as much as the grade.
Kwikset SmartKey
Many newer houses here came with Kwikset SmartKey locks, which rekey with a small tool and a working key rather than by changing pins. That makes a rekey even quicker, but it only works with the current key, and a mixed house still needs matching cylinders.
The usual answer
Most houses end up with a mix: the good locks rekeyed, one or two poor ones replaced, and every door on a single new key. That is the answer we give at the door, lock by lock, rather than quoting a full set by default. See our rekey and lock change pages.
Questions people ask
Is rekeying less secure than replacing?
No, for the purpose of cutting off old keys it is exactly as effective. Replacing only adds security if the new lock is genuinely better than the old one.
Can a smart lock be rekeyed?
Its key cylinder usually can, so the backup key matches the house. The codes and app are reset separately.
How many locks can be rekeyed in one visit?
As many as the house has. A few minutes per cylinder, and a typical home with four exterior locks is done well within an hour.
Will rekeying fix a sticking lock?
Only if the pins were the problem. Most sticking comes from the door not lining up with the strike, which is a separate, usually quick, fix.