Backset, Bore and Handing: The Three Numbers That Decide Whether Your Lever Fits

Most door hardware returns come down to one of three measurements. Here is how to read your door before you order — and which of the three BEX has already taken off your list.

Knobs and levers get the attention. The latch does the work.

Before any lever reaches a door, three numbers decide whether it will fit, swing the right way, and latch cleanly for the next twenty years. They are backset, bore, and handing. Get them right and installation takes minutes. Get one wrong and you are standing at the door with a drill and a decision you did not want to make.

This is the guide we wish came with every door.

Backset: the number that causes the most returns

Backset is the distance from the edge of the door to the center of the bore hole — the big round hole your lever passes through. In North America there are two standards: 2-3/8 inch and 2-3/4 inch.

Residential interior doors are usually 2-3/8”. Exterior and many commercial doors are usually 2-3/4”. “Usually” is the problem. Pre-hung doors from different suppliers, older homes, and remodels mix the two freely, and a latch cut for one will not reach the strike on the other.

How to measure it: Close the door. Put a tape on the edge of the door and measure to the center of the bore hole. If you cannot see a bore yet (new door, no hardware), measure from the edge to the center of the existing latch face on the edge of the door, then add nothing — the latch face is centered on the backset.

Where BEX comes in. Every BEX set ships with a latch that is adjustable between 2-3/8” and 2-3/4”. The installer sets it on site; there is no second latch to stock and no second part number to get wrong. One number has been taken off the list.

Bore: the hole everything passes through

The bore is the large hole through the face of the door. The modern standard is 2-1/8 inch. Older doors, especially pre-1960s, can run 1-1/2” to 1-3/4”, and some European-sourced doors are different again.

There is also the edge bore — the hole drilled into the edge of the door for the latch body. Standard is 1 inch, which fits a 1” latch face. Some doors have a 7/8” edge bore and need a drive-in latch instead of a face-plate latch.

How to measure it: Measure the diameter of the face hole with a tape across its widest point. Measure the edge-bore the same way. If the face bore is under 2-1/8”, the rosette (the round or square plate behind the lever) must be large enough to cover the old hole; a BEX Halo rosette is 2-5/8” across, which covers a standard 2-1/8” bore with a quarter inch to spare on every side.

Cross-section detail. BEX sets are built for a standard North American prep: a 2-1/8” cross bore and a 1” edge bore, on doors from 1-3/8” to 1-3/4” thick. Thicker doors — up to 3.5” — take a thick-door kit with an extended cylinder, a longer square steel spindle and longer rosette screws. The strike is mortised to match the latch. This is the part of the system no one sees, and it is held to the same tolerance as the lever you touch every day.

Handing: the number that is only a decision for levers

Handing describes which side the hinges are on. Stand on the exterior side of the door — the side you would knock on — facing in. If the hinges are on your left, it is a left-hand door and takes left-hand hardware. Hinges on your right: right-hand. (Knobs are symmetrical and have no handing; this is a lever question.)

A lever handed wrong points up instead of down. It is the second most common reason a set comes back.

Where BEX comes in. Every BEX product page carries a handing diagram one click from the order button, and the dealer portal walks the question before a part number is generated. Either way, the answer is settled before the box ships, not at the door.

What’s behind the rosette

Every BEX lever and knob shares the same internal chassis: a Grade 2 heavy-duty tubular chassis with a component BEX calls the CF — independent heavy-duty springing on each side that addresses the two things builder-grade levers do over time: sag and loosen. What changes from one design to the next is the rosette and the grip — the two parts you see and touch. Passage and Privacy share the same rosette and the same door prep; Privacy adds a locking pin housed inside the rosette, engaged with a press, so a bedroom or bath door needs no second piece of hardware and no extra milling.

Two details you will feel every day without noticing. The latch turns through 28 degrees to retract — builder-grade latches need 40 to 60 — so the lever moves less and the wrist moves less. And the latch bolt carries an anti-friction polymer insert, which is why a BEX door closes nearly silently and why the strike plate does not wear a groove over the years.

That is deliberate. One chassis means the tolerances are proven once, the templates are the same for every design, and the installer who fitted a Ventura on Monday fits a Munich on Friday with the same template and the same motion. It also means a design or finish change on a project is a face swap, not a re-prep of the door. The mechanism is covered for life; the finish for ten years; and the warranty transfers to the next owner of the house.

Before you specify

• Measure backset on three doors, not one. Remodels mix standards.
• Confirm bore diameter on any door older than 1970 or sourced outside North America.
• Confirm edge bore (1” standard) and whether a drive-in latch is required.
• Note door thickness. BEX standard fits 1-3/8” to 1-3/4” doors; up to 3.5” with a thick-door kit.
• Check the strike. A full-lip strike needs a deeper jamb mortise than a T-strike; order the strike with the latch, not after.
• Handing (levers only): stand outside, face in, note the hinge side. Write it on the schedule.
• Hand tools only. Power drivers strip the internal threads and snap screw heads; the install needs a screwdriver and nothing else.

Frequently asked questions

What is the most common door backset? 2-3/8” for interior residential doors and 2-3/4” for exterior and commercial doors. BEX tubular latches adjust to both.

Do door knobs have a handing? No. Knobs are symmetrical. Only levers are handed; stand on the exterior side facing in and note which side the hinges are on.

What bore size do I need for a BEX lever? A standard 2-1/8” cross bore and 1” edge bore on a 1-3/8” to 1-3/4” door. Smaller face bores are covered by the 2-5/8” rosette; doors up to 3.5” thick take a thick-door kit.

Is the Privacy function a different door prep? No. Passage and Privacy share the same rosette and the same prep; the Privacy lock pin is built into the rosette.

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Related reading: Coordinating Door Hardware Finishes Across a Project · Before You Specify: The BEX Pre-Order Checklist