What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
A key that breaks off inside the lock almost always tells a two-part story: the key itself was worn, cracked, or a poor copy, and the lock it was turning was already stiff from worn internal pins or misalignment. The fragment left in the cylinder is now the whole problem, and the next few minutes matter more than the repair that follows. Everything you do to the keyway before help arrives can either leave the fragment sitting visibly at the front of the cylinder, ready to extract, or push it deeper, bend it, and turn a quick extraction into a cylinder replacement.
This is inconvenient rather than dangerous, unless the broken key leaves you locked out with the urgency factors described for a lockout, or leaves a door unable to lock at all, in which case treat securing the home as the priority. Do not keep using that lock or inserting the broken stub to try your luck: each attempt can push the fragment further in. If the door is currently locked and secure, it can wait for a normal booking; if it is unlocked and cannot be locked, call the same day.
Keys thin and crack with years of use, especially at the deepest cut near the blade shoulder. A key copied repeatedly from an already worn original gets weaker and less accurate each generation, until a normal turn on an ordinary day is the one that snaps it cleanly at its thinnest point.
A cylinder with worn pins, internal corrosion, or years of grit asks for more turning force than it should. The key absorbs that extra force until it fails. This is why a broken key often follows weeks of jiggling and effort that felt normal at the time: both the key and the lock were wearing out together.
If the door has dropped on its hinges or the frame has shifted, the deadbolt may be dragging against its strike rather than sliding freely. The key then has to muscle the bolt through that friction on every use, which fatigues the key and can leave the bolt half-thrown as well as the key broken.
A similar-looking key from another lock, forced even partway, can bind and snap, and pulling a key out while it is still slightly turned stresses it at its weakest point. If the fragment has unfamiliar cuts when it is finally seen, a wrong-key attempt may be the real explanation.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $75–$220 |
| Major job — complex, hidden, or replacement-level work | $220–$500 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
The honest homeowner contribution here is mostly restraint: stop, look without touching, keep both pieces, and secure the door. Extraction itself is professional work with purpose-made tools, and on most locks a locksmith can remove the fragment without damaging the cylinder, then cut a fresh key from the pieces or the code. Call a pro in essentially every case where the fragment is not already sitting proud enough to slide out untouched. If the lock was stiff enough to break a key, ask for the cylinder and door alignment to be assessed too, or the new key inherits the same problem.
Often it can be saved. If the fragment is extracted cleanly and the cylinder itself is sound, the lock goes back into service with a new key. Replacement becomes likely when the fragment has been pushed deep or glued, when home extraction attempts have damaged the keyway, or when the cylinder was already worn enough to cause the break. A locksmith can usually tell you which situation you are in once the fragment is out.
Metal fatigue is gradual, then sudden. A key develops a fine crack at its thinnest cut over many uses, often helped by a lock that has grown stiffer with wear or a door that has shifted. The final turn is rarely harder than usual; it is simply the turn where the crack completed. That is why the condition of the lock matters as much as the new key when preventing a repeat.
The pieces are useful, since together they show the full cut profile and any code stamped on the head, but cutting from a worn original reproduces its wear. A good locksmith may decode the cuts and cut to the original specification instead, giving you a key that works like the first one did. Bring both pieces and any original key you still have, and ask which will give the more accurate result.
If the tip is genuinely protruding and the cylinder is in its resting position, gentle, straight-out handling is the only scenario that sometimes works at home, but any sideways wiggling can snap or wedge it. Given how easily a nearly-out fragment becomes a fully buried one, the safer advice is still to leave it for extraction tools. If you do touch it and it resists at all, stop immediately rather than increasing force.
Describe what's actually happening and get a personalized diagnosis — DIY vs. call-a-pro verdict, real cost estimate, and top-rated local pros.