When upgrading door handles, most people focus on the style and finish of the handle itself. However, the tubular latch (the mechanism inside the door that keeps it shut) is the engine of the operation.
If you are replacing handles on existing doors, measuring the current latch is critical. Here is why.
- Why can’t I just buy any standard latch?
“Standard” is a misleading term in door hardware. While there are common sizes, there is no single universal size. If you buy a latch that doesn’t match your existing door preparation, the spindle (the metal bar connecting the handles) will not line up with the existing hole in your door.
- What is the most important measurement?
The critical measurement is called the Backset.
- What it is: The distance from the edge of the door (the faceplate) to the center of the square hole (the follower) where the spindle goes through.
- Why it matters: This dictates exactly where your handle will sit on the face of the door.
Note: Do not confuse the Backset with the Case Depth (the total length of the latch). The total length is less important than where the spindle hole sits.
- What happens if I buy the wrong size?
If you purchase a replacement latch with the wrong backset, you will face two main problems:
- If the new latch is too short: You will have to drill a new hole closer to the edge of the door. This often leaves the old hole partially exposed behind the handle rose, which looks unsightly and is difficult to fix.
- If the new latch is too long: You will have to chisel out the door further back. This is labor-intensive and requires precise woodworking skills.
- What are the common sizes I should look for?
While sizes can vary, the two industry standards you will encounter most often are:
- 64mm (approx. 2.5 inches): Usually used for lever handles.
- 76mm (approx. 3 inches): Often used for door knobs or larger handles.
- Does the type of handle (Knob vs. Lever) change the latch I need?
Yes, it often does.
- Door Knobs: These usually require a deeper latch (typically 76mm or larger). If you use a short latch with a round knob, your hand may scrape against the door frame (the architrave) when you turn the knob.
- Lever Handles: These project away from the latch, so a shorter backset (typically 64mm) is usually sufficient to provide knuckle clearance.
- Can I just keep my old latch and put new handles on it?
Technically, yes, provided your new handles are compatible with the existing latch mechanism. However, we generally recommend replacing the latch at the same time because:
- Wear and Tear: If the handles are old enough to replace, the internal springs of the latch are likely worn out too.
- Spring Strength: New heavy handles might be too heavy for an old, weak latch, causing the handle to droop. Newer “heavy-duty” latches are designed to support the weight of modern solid levers.
- How do I measure my existing latch correctly?
You don’t need to remove the latch from the door to get a rough idea, but removing it is the most accurate method.
- Without removing: Measure from the edge of the door to the center of the handle’s spindle.
- With removing (Recommended): Take the latch out. Measure from the metal faceplate to the center of the square hole (the follower).
Summary Table: The “Standard” Sizes
| Metric Measurement | Imperial Equivalent | Best Suited For |
| 64mm Backset | 2 ½ Inch | Lever Handles |
| 76mm Backset | 3 Inch | Door Knobs (provides knuckle clearance) |
| 102mm+ Backset | 4 Inch+ | Large doors or oversized hardware |
Would you like me to create a simple step-by-step guide on “How to Replace a Tubular Latch” to go alongside this FAQ?
Yes please
Here is a simple, step-by-step guide to replacing a tubular latch. This is designed to be printed out or read on a phone while doing the job.