A key snapping inside a lock is one of the most frustrating things that can happen at a door. One moment you are turning the key as usual; the next you are holding half of it, with the rest stuck in the cylinder. It is also one of the problems people most often make worse while trying to fix it. This guide explains why keys break, what to avoid, and what actually gets the door working again.

Why keys break

Keys do not usually break without warning. The most common causes are:

A stiff or dirty lock. When a cylinder is full of dust, old graphite or corrosion, the key has to be forced to turn. Over time, that extra force fatigues the metal. Near the beach in Coogee, Bronte and Bondi, salt air speeds up corrosion inside cylinders, so stiff locks are common.

A worn key. Keys wear with use. The cuts round off, the blade thins and the shoulder weakens. Copies of copies are especially prone to this, because small errors build up.

A poor-quality copy. Keys cut from soft metal or cut slightly wrong need more force to turn and are more likely to snap.

A misaligned door. If a door has dropped, the bolt binds against the strike plate. People push harder on the key to compensate, and the key takes the strain.

Using the key as a handle. Pulling a door closed by the key puts sideways force on it, which it was never designed for.

The common thread is force. A lock in good condition should turn with light finger pressure. If yours does not, it is a warning.

What not to do

When a key breaks, the instinct is to dig it out. These are the mistakes we see most:

Do not push another key in. It pushes the broken piece deeper and can bend the pins.

Do not use superglue on the broken piece. Glue can run into the cylinder and set the pins in place, turning a simple extraction into a lock replacement.

Do not dig with pins, paper clips or knives. These often push the fragment further in or scratch the cylinder.

Do not try to turn the broken piece with pliers. If the piece is not fully inserted, turning can damage the cylinder. If the door is locked, it may not open anyway.

Do not spray household oil in. It may help briefly but leaves residue that attracts grit.

Do not force the door. A broken key is a small problem. A broken door frame is a big one.

What you can safely try

There are only a couple of things worth trying yourself:

If a good length of key is sticking out, you can try gently pulling it straight out with fine tweezers or needle-nose pliers, without twisting. If it does not come easily, stop.
If the door is open, leave it open and secure the property another way until the lock is fixed.

If neither works, leave the piece where it is and call a locksmith.

What a locksmith does

Extracting a broken key is a routine job for a locksmith. A typical visit:

Assess the position. We look at how far the piece is inserted and whether the cylinder is in the locked or unlocked position.
Extract the piece. Using purpose-made extraction tools, we work the fragment out without damaging the pins.
Check the cylinder. We inspect the lock for the problem that caused the break: dirt, corrosion, wear or misalignment.
Service or repair. If the lock is stiff, we clean and lubricate it. If the door is misaligned, we adjust it.
Cut a new key, if needed, from the broken pieces or from the lock.
Test. We test the lock with the new key from both sides of the door.

In most cases, the lock can be kept. Replacement is only needed if the cylinder has been damaged, often by earlier attempts to dig the key out.

Our lock repair page explains how we service stiff and worn locks.

If you are locked out because of a broken key

If the key broke while the door was locked, you cannot get in until the piece is removed or the door is opened another way. Treat it like a lockout:

check for other legitimate ways in;
find your ID or proof of address;
call a locksmith and explain that the key has snapped inside.

Our emergency locksmith and lockout service pages explain what to expect. We work 7:00 AM to 12:00 AM, seven days.

If the key broke in a car, padlock or safe

Car keys, transponder keys, padlocks and safes all need different approaches. We focus on homes and businesses, so for cars you may need an automotive locksmith. Let us know what the lock is when you call and we will be honest about whether we can help.

Should you replace the lock afterwards?

Not usually. After extraction, the lock can often be serviced and kept. Replacement makes sense if:

the cylinder was damaged during the break or extraction;
the lock is badly worn or corroded;
the lock cannot be serviced because parts are unavailable; or
you wanted to upgrade anyway.

Our guide rekey or replace locks? helps you decide.

How to stop it happening again

Fix stiff locks early. If a key needs force, have the lock serviced. It is far cheaper than an emergency visit.

Replace worn keys. If your key looks rounded or thin, have a new one cut from a good original, not from a worn copy.

Use quality copies. Ask for keys cut on proper blanks by someone who checks them in the lock.

Keep a spare. If the main key breaks, a spare stored with someone you trust may save a call-out.

Do not pull doors closed by the key. Use the handle.

Lubricate properly. A dry lubricant made for locks, used once or twice a year, keeps pins moving freely. Near the ocean, more often helps.

Check door alignment. If you have to lift or push the door to lock it, have the hinges or strike adjusted.

Why coastal locks are more at risk

Living close to the ocean is wonderful, but salt is hard on metal. In Coogee and the neighbouring beach suburbs, we often see:

springs inside cylinders weakened by corrosion;
pins that stick in place;
keys that slowly need more force over months.

Because the change is gradual, people often do not notice until a key snaps. Servicing coastal locks regularly is one of the simplest ways to avoid it.

Different locks, different breaks

Where and how a key breaks affects what happens next.

Front door deadlocks and deadlatches. These are the most common. The key usually snaps at the shoulder, just outside the keyway, leaving most of the blade inside. If the lock was turned partway when it broke, the cylinder may be stuck between positions. Extraction usually solves it, but the cylinder needs checking for damage afterwards.

Unit doors in strata buildings. If the lock is part of a restricted key system, a new key may need to be ordered through the building's system holder after extraction. Contact your building manager as well as a locksmith.

Padlocks. Broken keys in padlocks can often be extracted, but for cheap padlocks it is sometimes simpler to cut the padlock off and replace it, if you own it and it is not securing anything belonging to someone else.

Window locks. Window lock keys are small and fragile. If one breaks, avoid forcing the window, as you can damage the frame. Extraction or replacement of the window lock is usually straightforward.

Mailbox and cabinet locks. These cheap cam locks are often easier to replace than to extract from.

Keeping the broken pieces

If a key breaks, keep both halves. A locksmith can often cut a new key from the pieces, which avoids having to decode the lock. Tape the halves together or keep them in a small bag so they are not lost.

When the broken key is a spare you rarely use

Keys that sit in drawers for years are often copies of copies, cut on worn blanks. If you only use a spare occasionally and it breaks, the problem is probably the key, not the lock. Have new spares cut from your best original key, and test each one in the lock before relying on it.

The honest summary

Keys break because of force, usually from a stiff lock, a worn key or a misaligned door. Avoid pushing in another key, using glue or digging with tools. Leave the piece and call a locksmith, who can usually extract it, fix the underlying cause and keep the lock.

If a key has broken in a lock in Coogee or nearby, call Local Coogee Locksmith Service on 02 5023 1337, open 7 days, 7:00 AM to 12:00 AM, at 186 Arden St, Coogee. You can also request a quote or contact us.

Key Broken in the Lock? What to Do (and Not Do)