Door Backset and Thickness: Measuring Before You Order a Lever

Door hardware is less forgiving than cabinet hardware, because the lock body has to sit inside a hole that already exists. Three measurements settle whether a lever set will go on.

Backset

Backset is the distance from the edge of the door to the centre of the large bore hole. Two sizes cover most interior doors: 60 mm and 70 mm, sometimes quoted in inches as 2 3/8 and 2 3/4. Many sets are adjustable between the two; many are not. If yours is not adjustable and the backset is wrong, the latch will not reach the strike plate.

Bore diameter

The large hole through the door face is usually 54 mm (2 1/8 inch). The smaller hole through the edge of the door for the latch is typically 25 mm (1 inch). A rose or escutcheon can cover a slightly oversized face bore, but it cannot cover one that is much too large, and it cannot help at all if the bore is too small.

Door thickness

Most interior doors run 35 to 45 mm thick. Lever sets state a range, and the spindle and screws supplied are cut for that range. A door outside the range needs a longer spindle and longer screws, which are not always available separately, so it is worth checking before ordering rather than after.

Handing

Many modern levers are reversible and will work on a left- or right-hand door without modification. Some entry sets and most handlesets are handed. Where a product is handed, the listing says so; where it is reversible, it says that too.

Privacy, passage and keyed

• Passage: no lock at all. Corridors, cupboards, connecting doors.
• Privacy: a push button or turn on the inside, with an emergency release outside. Bathrooms and bedrooms.
• Keyed entry: a key cylinder outside. Front doors, and anywhere a key is genuinely wanted.

Choosing the wrong function is a more common mistake than choosing the wrong size, and it is not something a bigger rose will fix.

What the listings give you

Every lever and entry set we stock states backset, whether it adjusts, the bore sizes it expects, the door thickness range, the function and whether it is handed or reversible. We do not carry out installation and we are not a locksmith service, so the measurement is yours to take; the numbers you need in order to take it are on the page.