If you are fitting a smart lock, one measurement decides whether the job takes ten minutes or turns into a headache: the mortise size. Choose the wrong one and nothing lines up — the handle sits crooked, the cylinder does not reach, and the bolt refuses to throw. This detailed guide from Covlor® explains the common smart door lock mortise sizes — 5050, 6068, 6072, 4585 and more — what the numbers mean, how to measure your own, and how to match the right fit.
What the Mortise Numbers Actually Mean
A mortise code is not random — it describes the lock body’s key dimensions in millimetres, most importantly the backset (the distance from the door edge to the centre of the cylinder) and the centre distance between the handle spindle and the cylinder. When these match your door’s existing cutout, the new lock’s handle, cylinder, and bolt all align perfectly. When they do not, the parts simply will not sit where the holes are. If you are new to the concept, our mortise guide covers the basics.
Common Mortise Sizes Explained
India uses a handful of standard sizes, and knowing them makes buying far easier:
| Mortise | Typical Use |
|---|---|
| 6068 | The most common size in India — standard residential main and internal doors |
| 5050 | Compact lock bodies for lighter or narrower doors |
| 6072 | A larger backset for heavier or wider doors |
| 4585 | Slim-profile doors and many metal doors |
The 6068 standard dominates Indian homes, which is why most Covlor® locks are built around it. But older doors, imported doors, and some metal frames use other sizes, so it always pays to check rather than assume.
How to Measure Your Mortise
You do not need special tools — just a tape measure and a few minutes. Open your door and look at the lock body set into the edge. Measure three things: the backset (from the door edge to the centre of the cylinder or keyhole), the height and width of the faceplate (the metal strip on the door edge), and the overall door thickness. Write these down. Together they tell you which mortise code your door uses and whether a given lock will drop straight in.
Matching a Smart Lock to Your Mortise
Once you know your size, matching is simple. If your door uses the common 6068 mortise, most Covlor® Smart AI Door Locks fit directly with no modification. If it uses a different size, the cutout may need to be adjusted — enlarging is straightforward in wood but should be done by a professional in metal. Never force a lock into a cavity that is too small; that leads to exactly the kind of installation mistakes that cause long-term misalignment and battery drain.
What If My Door Uses a Rare Size?
Doors with a 5050, 4585, or non-standard mortise are common in older or imported builds. In most cases a carpenter can adapt a wooden cutout to accept a standard 6068 lock, or a filler plate can bridge small differences. For metal doors, professional cutting is the safe route. If you are unsure, send Covlor® support your measurements or a photo of the lock edge and we will confirm the right model before you buy.
Why Getting the Size Right Matters
An accurate mortise match is the foundation of a lock that works smoothly for years. The bolt throws cleanly, the motor is not strained, the battery lasts its full life, and the sensors stay aligned. A poor match undermines all of that from day one — so this single measurement is well worth getting right.
Frequently Asked Questions
What mortise size do most smart locks use?
In India, 6068 is the most common standard, and most Covlor® smart locks are designed to fit it directly.
How do I know my mortise size?
Measure the backset, faceplate dimensions, and door thickness on your existing lock — or send a photo of the lock edge to support to confirm.
What if my door has a 5050 or 4585 mortise?
Smaller or non-standard mortises may need the cutout adjusted to fit a standard lock. A professional installer can enlarge it accurately, especially in metal.
Can I change a mortise size myself?
Enlarging a mortise in wood is possible with care and the right tools; in metal, professional cutting is strongly recommended.
Will the wrong mortise size damage my lock?
Forcing a lock into a mismatched cutout can damage both the lock and the door, and causes misalignment that drains the battery. Always match the size first.
Find your perfect fit
Covlor® Smart AI Door Locks fit standard mortise doors — with a 2-year warranty and free installation on 2+ locks in Bihar.
