A replacement euro cylinder costs £15–£40 for the part if you fit it yourself, or £80–£160 fitted by a locksmith including labour. The physical swap takes minutes once the correct size is in hand, which is why measuring, not money, is where most people slip up. Prices first, then how to measure your barrel properly.
Check that your door actually has one
Euro cylinders are the long barrels visible on the edge of most uPVC doors, many composites and some aluminium ones, usually working a multipoint locking strip. If your key goes in at roughly handle height, that is almost certainly what you have. Older aluminium frames sometimes use an oval profile instead, which swaps the same way but is a different part, so check before ordering anything. And if the real problem is a door that will not lock rather than a tired cylinder, read our guide to uPVC door repair costs first, because the mechanism, not the barrel, may be the fault.
What a replacement costs
Two routes. Supply your own cylinder for £15–£40 depending on security rating and finish, and swap it with a screwdriver. Or have a locksmith supply and fit one for £80–£160 including labour, which buys correct sizing, a proper part and somebody accountable if anything sticks afterwards. Fitted prices follow the usual structure: a £30–£60 callout plus time at £50–£80 an hour, and the swap rarely fills the hour. Out-of-hours work runs nearer £90–£120 an hour, so book daylight where the situation allows. For the wider picture across every job type, see our UK locksmith cost guide. To sense-check fitted prices where you live, compare local locksmith prices before you commit either way.
Like-for-like, or upgrade while you are at it?
If your current cylinder is a basic model, replacing it is the natural moment to fit an anti-snap one. Cylinders can be attacked by force at the door’s edge, and anti-snap designs are built to resist exactly that, which is why security standards and police-backed crime prevention schemes favour them on exterior doors. They sit at the top of the price bands above rather than outside them. Cylinder security is graded publicly under the TS007 star system, from one to three stars, so look for the stamp on the faceplate, or simply tell the locksmith that security is the priority and let them quote accordingly.
How to measure your cylinder
- Open the door and find the single fixing screw in the middle of the lock strip on its edge. Undo it fully.
- Insert the key and turn it gently, a few degrees, until the cam (the tab behind the cylinder) lines up with the cylinder body. Aligned, it slides freely.
- Slide the cylinder out towards you, with a gentle wiggle if it resists. Note which way the cam was facing.
- Lay it flat and measure from the centre of the fixing screw to each end, in millimetres. A 35/45 cylinder measures 35mm one side, 45mm the other, 80mm overall.
- Order the same split. Cylinders come in 5mm steps covering most door thicknesses, and the two halves need not match each other, only your door.
Why size matters more than brand
A correctly sized cylinder sits flush with the door furniture or protrudes no more than about 3mm on either side. Protrude further and you hand anyone with a pair of grips a purchase point; sink too deep and the lock binds and wears oddly. Oversizing is the classic mistake because close enough feels fine at the till. Measure twice, order once, and if your door falls between sizes, take the closer fit rather than the larger one.
DIY swap or call a locksmith?
If the door opens, the fixing screw cooperates and your measurements are done, this is a genuine quarter-hour DIY job. Call a professional instead when:
- the cylinder is seized, snapped or spins loosely with no resistance;
- the door will not open, so the fixing screw is unreachable;
- the fault seems to sit in the multipoint strip rather than the cylinder;
- you want an anti-snap upgrade supplied, sized and fitted in one visit.
Any competent local firm handles this work daily. Our guide on choosing a locksmith you can trust covers the checks worth making before you book one.
Get a cylinder replaced near you
Whether you want a second opinion on your measurements or the whole job taken off your hands, find a local locksmith near you and compare upfront fitted prices side by side. Readers in bigger cities can start with locksmiths in Birmingham or locksmiths in Leeds, where listings show rates and services before you call. One question does most of the work on the phone: what is the total fitted price, including the cylinder itself?