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Tubular mortice latch: what to measure before buying

Updated: October 2026

You have the old latch in your hand, and the packet uses two millimetre figures that do not agree. A tubular mortice latch is the round case a lever turns so an ordinary UK internal door stays shut. It does not lock, and it is not the ironmongery named on a fire-door certificate. This page is the order: what you are buying, how you measure, then spring and door type. Prices are on the [door fitting comparison](/hub/door-and-window-security/door-fitting). Peter F. used those listings and UK fitting notes, updated in October 2026. A qualifying purchase through an amazon.co.uk link can earn a commission at no extra cost to you.

You have the old latch in your hand, and the packet uses two millimetre figures that do not agree. A tubular mortice latch is the round case a lever turns so an ordinary UK internal door stays shut.

Our top picks

MOXYOY MOXYOY 45 mm tubular latch

Best overall

MOXYOY MOXYOY 45 mm tubular latch
8.0/10about £5.49
View offer
Yale Yale PM888 tubular mortice latch

Rank 2

Yale Yale PM888 tubular mortice latch
8.8/10about £5.99
View offer
Chliinl Chliinl 45 mm tubular latch

Rank 3

Chliinl Chliinl 45 mm tubular latch
7.6/10about £5.29
View offer
On this page
  1. 1.What you are actually buying
  2. 2.Measure case and backset
  3. 3.Spring, handing, and the door
  4. 4.Where the three listings sit

What you are actually buying

A tubular mortice latch is a short round body that slides in from the door edge. A bevelled bolt sticks out until the lever turns a square follower and pulls the bolt back. The Guild of Architectural Ironmongers describes a tubular latch as the fitting for internal doors that do not lock. BS 3621 is the thief-resistant lock mark many insurers name for a final exit, and none of these listings shows it. The Yale PM888 listing says locking is not required, then a separate attribute says Key Unlock. The bullets do not describe a key. The Chliinl title uses the words internal door lock, and the bullets describe a latch with four screws.

Measure case and backset

Backset is the distance from the faceplate, on the door edge, to the centre of the spindle. Case length is how far the round body reaches into the door. UK catalogues usually pair a 64 mm case, which is 2½ inches, with a backset of about 44–45 mm, and a 76 mm case, which is 3 inches, with a backset of about 56–57 mm. Copy the old latch if you can still remove it. The Yale listing says the mortice latch has a 2.5 inch / 64 mm backset. Yale's UK fitting sheet, for a 64 mm latch, places the spindle 45 mm from the edge. Read 64 mm on that packet as the case length unless your own tape says otherwise. That conflict is on the 64 mm or 76 mm door latch page.
MOXYOY MOXYOY 45 mm tubular latch

Testsieger

MOXYOY MOXYOY 45 mm tubular latch
8.0/10about £5.49
View offer

Spring, handing, and the door

Wickes, on the brass Yale PM888-pattern latch at about £6, says the bolt is withdrawn by a sprung lever and that the latch is not for unsprung lever handles. None of the three amazon.co.uk listings states a fire test to BS EN 1634-1. The MOXYOY title says sprung lever handles. Yale and Chliinl say left- and right-handed doors. The MOXYOY listing does not state handing. An ordinary bedroom or passage door is in scope. A fire door, a flat entrance, or any leaf with a closer and intumescent strips is not. What an internal latch is allowed to do is on the internal door latch page.

Where the three listings sit

These three are examples of size wording, not a winner's podium. None of them states BS EN 12209, BS 3621, or a fire rating. The drill sequence is on how to fit a tubular latch.

Common questions

How do I measure the latch without taking the door off?
Open the door and measure from the edge of the door to the centre of the existing handle hole. That distance is the backset you need to match. About 44–45 mm usually belongs with a 64 mm case, and about 56–57 mm with a 76 mm case. If the old latch is still in the door, take it out and copy the faceplate and the bolt. The door can stay on its hinges for that check.
Do I need a latch that locks?
You need a lock only if the door has to keep someone out, or a bathroom has to privacy-lock with a turn. A tubular mortice latch holds the door shut. The Yale bullets say locking is not required. A key means a sashlock or a BS 3621 deadlock, which are different fittings. A high review count on a latch is not a security grade.
Should the handles be sprung or unsprung?
Sprung levers carry their own spring and suit a light tubular latch such as the PM888 pattern Wickes describes. Unsprung levers rely on the latch spring, and a light one will let them droop. The MOXYOY listing names sprung lever handles. If your levers fall when you release them, none of these three is the heavy-sprung latch that job needs.
Can I use a tubular mortice latch on a fire door?
Not on the evidence these listings give you. None states a fire rating or a BS EN 1634-1 test. A fire doorset includes the ironmongery, so a swap that is not in the door's evidence is a different job. If the door has a closer, intumescent strips, or a fire-door sign, stop and use the latch the certificate names.
What if the new latch is 2 mm short?
The handles will not meet the spindle in the old holes. One MOXYOY review measured 43 mm against a stated and stamped 45 mm, and the buyer returned it. Check the new latch with a ruler before you enlarge anything. If the goods do not match the size in the description, the Consumer Rights Act 2015 is the route, and the short-term right to reject normally runs for 30 days.
Which listing matches a 45 mm edge measurement?
MOXYOY states a 45 mm edge distance, and Chliinl states a 45 mm margin. Yale's fitting sheet uses 45 mm from the edge on a 64 mm latch, even though the listing calls 64 mm the backset. Match the tape to the latch in your hand. A stated 45 mm that measures 43 mm is not a match, however the title is worded.

Related pages

Best tubular latch

Door fitting

64mm or 76mm door latch: case length is not the backset

How to fit a tubular latch on an ordinary internal door

Internal door latch: when a tubular latch is enough

Sources

Public UK and manufacturer sources from the research digest. Prices, stars and review counts are the amazon.co.uk figures in this comparison, not a live check on 21 October 2026. None of these listings was treated as BS 3621 or fire-door ironmongery.

  1. ERA 189-33 tubular mortice latch fitting instructions (retrieved 21 October 2026)
  2. Yale tubular latch fitting instructions (retrieved 21 October 2026)
  3. More Handles tubular latch guide (retrieved 21 October 2026)
  4. Home Secure internal door latch measuring guide (retrieved 21 October 2026)
  5. GAI specifiers' guide: ironmongery and security, September 2024 (retrieved 21 October 2026)
  6. GOV.UK fire safety (England) regulations 2022: fire door guidance (retrieved 21 October 2026)
  7. Approved Document B: fire safety frequently asked questions (retrieved 21 October 2026)
  8. Consumer Rights Act 2015, sections 11 and 22 (retrieved 21 October 2026)