Internal door lock: which type to buy
Updated: October 2026
You are choosing an internal door lock for a bedroom, a bathroom or a WC, and the amazon.co.uk results look interchangeable. A slide bolt, a rotate bolt, a keyed lever, a 3-lever mortice sashlock and a stick-on lever lock each shut a different problem, and a millimetre on the title is not always a UK backset. Decide the job, then whether anyone must open the door from outside, then the measurement, then whether the door is a fire door. The [room door lock comparison](/hub/door-and-window-security/room-door-lock) holds the ten listings. Prices here are the amazon.co.uk shelf prices on 19 October 2026. Peter F. compared those listings with public UK ironmongery guides and did not lab-test the locks. A qualifying purchase can earn a commission at no extra cost to you.
You are choosing an internal door lock for a bedroom, a bathroom or a WC, and the amazon.co.uk results look interchangeable.
You are choosing an internal door lock for a bedroom, a bathroom or a WC, and the amazon.co.uk results look interchangeable. A slide bolt, a rotate bolt, a keyed lever, a 3-lever mortice sashlock and a stick-on lever lock each shut a different problem, and a millimetre on the title is not always a UK backset. Decide the job, then whether anyone must open the door from outside, then the measurement, then whether the door is a fire door. The room door lock comparison holds the ten listings. Prices here are the amazon.co.uk shelf prices on 19 October 2026. Peter F. compared those listings with public UK ironmongery guides and did not lab-test the locks. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Lock type | Outside opening | Fitting | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  QWORK QWORK rotate bolt | Rotate bolt | Not listed | Screws | 9.2 | about £5.95 | View offer |
| Best value |  JelKen Jelken 75 mm slide bolt | Slide bolt | Not listed | Screws | 9.0 | about £3.79 | View offer |
 XFORT XFORT 3-lever sashlock | 3-lever sashlock | Key | Mortice | 8.2 | about £10.99 | View offer |
On this page
What you are actually locking
A high star rating on a bolt does not answer a sashlock measurement, so name the job first. If you only need the door to stay shut while you are inside, and you can always reach the bolt, a surface bolt is the cheap hardware here. That band runs from about £3.79 to about £5.95: Jelken, lmytdo, YUOIP, the All-Pie pair, and the QWORK rotate bolt. None lists an outside release. T.H. Wiggans treats a slide bolt as the bathroom option they do not recommend, because nobody on the landing can undo it. If a guest or a child might fasten the door, read the bathroom door lock page before you buy.
A keyed bedroom is a different job. BaBahuanhuan, Movstriker and Faankiton are aluminium levers with a key outside and a turn inside, from about £9.99 to about £16.99. They are not a privacy thumbturn with a coin slot. Reviews on the Faankiton and Movstriker sets include people locked in when the spindle was short or the mechanism jammed. A like-for-like sashlock is the third job. The XFORT 51.05.65, at about £10.99, is the only mortice case here, with a brass latch and deadbolt and no handles in the box. The fourth job is a toddler who can push a lever. The Moonybaby two-pack, at about £7.99, only blocks that lever.
The measurements that decide the fit
Backset is the distance from the face of the door edge to the centre of the spindle. ERA’s measuring guide puts a common 64 mm case at about a 44 mm backset, and a 76 mm case at about a 56 mm backset. Builder Depot’s rule of thumb works from the outside: a handle centre about 45 mm from the edge suggests a 64 mm case, and about 55 mm suggests a 76 mm case. You can check that with the lock still in the door. Measure to the middle of the spindle, then compare it with the new case before you order.
The lever sets here advertise a 60 mm or 70 mm latch, which is not that 44 mm or 57 mm backset. BaBahuanhuan states a door of 25 to 45 mm and a latch of 60 or 70 mm, and it has only 12 reviews. One reviewer measured the backset at 90 mm and could not use the set. Faankiton MS0028 claims doors of 30 to 45 mm. A review of a 40 mm door said the inside thread was too short to lock from the room side. Movstriker states 30 to 50 mm and the same latch choice. If your holes were cut for a British 44 mm backset, a 60 mm latch is the wrong part. The XFORT title includes 65 mm. That figure is not labelled as the backset, so do not order it as a 65 mm backset and then chisel the door to suit. Match case depth, forend shape and the latch bevel to the old lock.
Standards that do not transfer
BS 3621 is a key-both-sides entrance standard. BS 8621 is the entrance standard for a key outside and a thumbturn inside, so you can leave without a key. A bathroom bolt is neither, and none of these ten listings prints those codes. Faankiton claims ANSI Grade 3. That is a US grade on the listing, not a British Standard. BS EN 12209 has a fire digit, and grade 0 on that digit means the lock was not verified for a fire or smoke doorset. The doorset itself is what BS EN 1634-1 or BS 476-22 tests.
The XFORT listing mentions CE and EN 1634-1 in a sentence, while a structured field says “App” and the bullets describe a mechanical key lock. There is no classification code and no certificate for a named door. GOV.UK says a fire door must still close fully into the frame, and London Fire Brigade guidance notes that modifications can undermine the doorset’s evidence. If you do not know whether the door is a fire door, a flat entrance or a common-part door, stop before you drill. The stop points, once you know the type, are on the how to fit a bathroom door lock page.
Which listing type survives that filter
After the job and the measurement, the listings sort into types rather than one winner. For an inside-only bolt you can always reach, the about £3.79 to £5.95 band is the rational buy, with a blank landing side. QWORK is the highest star line, 4.6 from 1,833 reviews, and reviewers use the turn as a bathroom snib. Jelken is about £3.79 with 4.5 from 1,887 reviews. A review says it stuck and locked the writer in, so an easy fit is not the same as a release from outside.
The keyed levers survive only when the door matches and you accept the reviews. They cost more and the stars are lower: BaBahuanhuan 4.0 from 12, Faankiton 3.8 from 160, Movstriker 3.6 from 184. Price is not a quality ladder. XFORT survives as a 3-lever swap when the old mortice matches and you already own handles. It does not survive as a 5-lever front-door lock. Moonybaby survives only as a no-drill block on a lever, with no EN 16948 claim on this ASIN. A Union 2226 bathroom mortice, from about £42.86, is the thumbturn pattern UK guides describe, and it is not in this set.
Common questions
What lock goes on a bedroom door versus a bathroom door?
A bedroom that must lock against other people is the keyed-lever job, and only after the thickness and latch match. A bathroom is a privacy job. T.H. Wiggans specifies a thumbturn and an emergency release, not a slide bolt. Use a bolt only if the person inside can always undo it and nobody else needs to get in. A stick-on lever lock is a fourth job, and it only blocks the handle.
Is a 3-lever sashlock the same as a 5-lever front-door lock?
No. Builder Depot puts 3-lever locks on internal doors and 5-lever locks on external doors, the pattern insurers usually ask about. The XFORT 51.05.65 is a 3-lever mortice sashlock with no handles in the box. It is not a BS 3621 entrance lock, and this set has no 5-lever case. Match it only to an old internal mortice.
What does backset mean, and is 60 mm the UK standard?
Backset is the distance from the door edge to the spindle centre. ERA’s common pairs are about 44 mm with a 64 mm case, and about 56 mm with a 76 mm case. These lever sets advertise 60 mm or 70 mm. One BaBahuanhuan reviewer measured 90 mm against a 60 to 70 mm claim. A 60 mm latch is not a 44 mm British backset.
How do I tell a 64 mm case from a 76 mm case without removing the lock?
Measure from the edge of the door to the centre of the handle. Builder Depot’s rule of thumb is about 45 mm for a 64 mm case and about 55 mm for a 76 mm case. Confirm against the old lock if you can remove it. The XFORT title’s 65 mm is not labelled as backset, so do not order from that figure alone.
When is a £4 slide bolt the rational buy?
When the door is ordinary internal timber, you can always reach the bolt, and nobody outside needs to release it. Jelken and lmytdo are about £3.79, YUOIP is about £3.99, and the All-Pie pair is about £4.49. It stops being rational when a child can fasten it, when the door is a fire door, or when you need a mortice that matches an existing cut-out.
What must I check before I drill a door that might be a fire door?
Identify the door before you mark a hole. GOV.UK says a fire door must close fully into its frame, and altering the leaf can sit outside the doorset’s evidence. If you cannot tell, ask the landlord, the managing agent or a joiner. Do not guess with a bolt of about £4 on a certified door. None of these ten listings is a fire-door certificate.
Related pages
Sources
Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are the amazon.co.uk figures in this comparison. None of the ten listings is treated as BS 3621, BS 8621 or Secured by Design.
- GOV.UK: Fire Safety (England) Regulations 2022 fire door guidance (retrieved October 2026)
- BSI: BS 3621 scope (retrieved October 2026)
- BSI: BS 8621 scope (retrieved October 2026)
- Secured by Design: locks (retrieved October 2026)
- Lloyd Worrall: BS EN 12209:2016 digit guide (retrieved October 2026)
- London Fire Brigade: GN 92 (retrieved October 2026)
- ERA: how to fit a mortice lock (retrieved October 2026)
- T.H. Wiggans: bathroom door locks (retrieved October 2026)
- BABYGO: door handle lock (retrieved October 2026)