Changing a lock cylinder: when, which one and what it costs

On a standard front door, changing a cylinder is a short job. The technician always works in the same order and will show you each step if you'd like.

• Measure: they measure the old cylinder in millimetres, from the fixing screw hole to each end (A on the outside, B on the inside).
• Remove the screw: with the door open, they take out the fixing screw on the edge of the door, in the lock's faceplate.
• Pull out the old barrel: they put the key in, turn it slightly until the cam lines up with the cylinder body, then slide the cylinder out of the lock.
• Fit the new cylinder: they slide it in, refit the screw without overtightening, and check it doesn't stick out too far on the outside.
• Test: every key is tried on both sides, door open and then closed, and the bolt must throw and retract smoothly.

On a 3-point or multipoint lock it works the same way: the cylinder is changed without taking the rest of the lock apart.

• After moving in: you don't know how many copies are out there. More on this below.
• After losing your keys or having them stolen, especially if your address was with them.
• After a burglary or attempted break-in: a forced or snapped cylinder no longer protects you. See after a break-in.
• When the key sticks or is hard to turn even though the door is well adjusted: the barrel is worn.
• When a key has broken inside the cylinder and can't be removed cleanly. See key broken in the lock.
• To upgrade: moving to an anti-pick, anti-snap security cylinder, or one with a key control card.

Three families for three needs. We show you the available models and their prices before fitting anything.

Standard cylinder

For internal doors, cellars, garden gates.

• Basic protection against picking
• Easy to copy keys
• Cheapest

High-security cylinder

For the front door of a flat or house.

• Better resistance to picking, drilling and snapping
• High key-security grade under EN 1303
• Often required or recommended by insurers

Cylinder with key control card

For rented property, shops, or after losing keys.

• Copies only cut on presentation of the card
• You know exactly how many keys exist
• Most expensive, most controlled

A new cylinder has to match exactly. You don't measure the overall length but two distances, both taken from the centre of the fixing screw: A towards the outside and B towards the inside. Two cylinders with the same total length can have different A and B sizes.

On the outside, the cylinder shouldn't stick out more than a few millimetres beyond the escutcheon or handle plate: anything that protrudes gives a burglar something to grip and snap. If your door has a security plate, we take it into account.

Not sure about your measurements? Send a photo of the door edge and of the cylinder from the front: we check before coming, and the technician measures again on site anyway.

• EN 1303: the European cylinder standard. Its code shows key-related security (1 to 6) and attack resistance (0 to D), among other things.
• EN 1627: burglar resistance of the whole door set (door, frame, hardware), RC1 to RC6. A great cylinder in a weak door isn't enough.
• VdS: German certification used as a reference by many insurers.
• A2P: French certification issued by CNPP, one to three stars.

Your home insurance may require a minimum level. Check before choosing: that's what counts if you ever make a claim. To compare models, see our guide to choosing a security cylinder.

The price covers the part and fitting. It mainly depends on the security level and the cylinder's measurements, which must match your door thickness.

For an accurate remote price, send us on WhatsApp a photo of the lock from the front and, if you can, the edge of the door where the fixing screw is. The quote is free: we reply with a fitted price including 17% VAT.

1. Photo on WhatsApp — Lock from the front, door edge if possible.
2. Options and fitted prices — One or more suitable cylinders, each with its price including VAT.
3. Fitting — The technician measures, fits and tests the cylinder with you.
4. Keys handed over — All the keys, the key control card if any, and a detailed invoice.

It's doable if you're inside with the door open, and you have your keys and a cylinder with the right measurements: a screwdriver is all you need. Same order as above, and test it with the door open before closing it. Full steps in our guide how to change a lock cylinder.

Call a locksmith instead if:

• you're outside without a key: the door has to be opened first, see locked out;
• the cylinder won't come out even with the screw removed, or the screw is seized;
• the lock has been forced and the faceplate or lock case is bent;
• you're unsure about the model or the measurements: the wrong cylinder gets bought twice.

You never know how many copies of your keys are out there: previous tenants, tradespeople, neighbours. A new cylinder costs far less than a burglary with no sign of forced entry, which insurers are often reluctant to cover.

If you rent, talk to your landlord or agency first. When you leave, you can refit the old cylinder or leave the new one, as agreed.