How to Measure Your Door for New Hardware: Backset, Bore, and Thickness Explained

Buying new door hardware is exciting until your shiny new lever shows up and won't fit the door. The latch is too short, the bore hole is the wrong size, or the lock body bottoms out before the door even closes. None of this is your fault — door hardware comes in a handful of standard dimensions, and if you don't know which ones your door uses, you're guessing.

The good news: measuring a door for new hardware takes about five minutes and a tape measure. This guide walks you through the three measurements that matter most — backset, bore, and door thickness — plus a few extras that catch people off guard.

Why These Measurements Matter

Door hardware isn't one-size-fits-all. Manufacturers like Emtek, Baldwin, and Schlage build their products to industry standards, but those standards include several variations. Your door was prepped (drilled and routed) for a specific configuration when it was built or last replaced. New hardware has to match that prep — or you'll be drilling new holes, filling old ones, or returning the order.

Get these three measurements right and roughly 95% of compatibility headaches disappear.

The Three Core Measurements

1. Door Thickness

What it is: How thick the door slab is, measured from one face to the other.

How to measure: Open the door. Place a tape measure or ruler across the edge of the door (the narrow side where the latch comes out). Measure from face to face.

Standard sizes:

• 1 3/4" — Standard for most exterior doors in residential homes
• 1 3/8" — Standard for most interior doors
• 2" to 2 1/4" — Common on custom, high-end, and some commercial exterior doors
• 2 1/2"+ — Specialty thick doors (often pivot doors or solid hardwood entries)

Why it matters: Most hardware ships configured for 1 3/8" or 1 3/4" doors. If your door is thicker than that, you'll need a thick door kit — a longer spindle, longer screws, and sometimes a longer tailpiece for deadbolts. Brands like Schlage and Baldwin offer these kits, but you have to order them specifically. Installing standard hardware on a 2" door without a kit means the lever won't seat properly or the deadbolt won't throw fully.

Tip: If your door is between standard sizes (say, 1 1/2" or 2 1/8"), measure to the nearest 1/16" and confirm with the manufacturer before ordering.

2. Backset

What it is: The distance from the edge of the door to the center of the bore hole (the big round hole where the knob or lever sits).

How to measure: Open the door. Place your tape measure on the door edge where the latch protrudes, and measure straight across to the center of the round hole.

Standard sizes:

• 2 3/8" — Most common for interior residential doors
• 2 3/4" — Most common for exterior residential doors
• Other — Commercial and some custom doors use different backsets

Why it matters: Most modern locksets include an adjustable latch that works with both 2 3/8" and 2 3/4" backsets — but not all do. Premium and decorative hardware (especially mortise locks and certain Emtek configurations) often require you to specify the backset at the time of purchase. Order the wrong one and the latch won't reach the strike plate, or worse, won't fit the door at all.

3. Bore Hole Diameter (Cross-Bore and Edge-Bore)

What it is: The diameter of the holes drilled in your door for the lock body.

There are actually two bores to think about:

Cross-bore (face bore): The large round hole through the face of the door where the knob or lever mechanism sits.

• Standard: 2 1/8" diameter

Edge-bore (latch bore): The smaller hole drilled into the edge of the door where the latch slides through.

• Standard: 1" diameter

How to measure: With the existing hardware removed, use a tape measure or ruler across the diameter of each hole. If the hardware is still installed, measure the existing trim plate or rosette — most manufacturers list compatible bore sizes in their spec sheets.

Why it matters: If your door has a non-standard bore (common on older homes, custom doors, or doors prepped for European hardware), you'll need either a bore conversion plate, a rosette large enough to cover the hole, or a different product line altogether. Mortise locks, in particular, don't use a cross-bore at all — they require a rectangular pocket routed into the door edge.

The Other Measurements That Trip People Up

Beyond the big three, a few additional dimensions cause problems when overlooked:

Center-to-center spacing (for handlesets and entry sets): If you're installing a handleset with both a deadbolt and a lever or knob, measure the distance between the center of the deadbolt bore and the center of the lower bore. Standard is 5 1/2", but some doors are drilled at 4" or other custom spacings.

Latch face plate dimensions: The latch face plate (the small rectangular plate on the door edge) needs to match the existing mortise. Standard plates are usually 1" x 2 1/4", but older doors may have round latch faces (drive-in latches) or oversized plates.

Strike plate location and size: Check that the strike plate on the door frame aligns with where the new latch will sit. If you're upgrading from a standard latch to a deadbolt, you may need to chisel out a new strike mortise on the frame.

Handing (for levers and some handlesets): "Handing" refers to which side of the door the hinges are on and which way the door swings. Most modern levers are reversible, but some decorative and commercial levers are handed — meaning a left-hand lever won't work on a right-hand door. To determine handing: stand outside the door (the side where the key goes in). If the hinges are on your right and the door opens away from you, it's a right-hand door. Hinges on the left = left-hand.

A Quick Measuring Checklist

Before you order, write down these numbers:

• [ ] Door thickness: ______
• [ ] Backset: ______
• [ ] Cross-bore diameter: ______
• [ ] Edge-bore diameter: ______
• [ ] Center-to-center (if handleset): ______
• [ ] Latch face plate dimensions: ______
• [ ] Handing (if applicable): ______

Take a quick photo of the door edge, the bore holes, and the existing strike plate while you're at it. If a question comes up later, you'll have the reference ready.

When to Call for Help

Most doors fall neatly into standard dimensions, but a few situations are worth a second opinion:

• Custom or imported doors (especially European-made) often use metric bores or mortise prep that doesn't match North American standards.
• Doors thicker than 2" require thick door kits that not every product line offers.
• Historic or antique doors may have non-standard prep that needs a specialty solution.
• Mortise lock installations are more complex than tubular locks and benefit from a professional assessment.

If your door falls into any of these categories, our team at RightSet Hardware can walk you through the compatible options before you order. Send us a few photos and your measurements, and we'll make sure the hardware you pick actually fits the door you have.

Ready to Shop with Confidence

Once you have your measurements, browsing for hardware becomes a much simpler exercise. You can filter by backset, confirm thick-door compatibility, and skip products that won't work for your door. The five minutes you spend with a tape measure today saves you the headache of returns and the disappointment of staring at hardware that doesn't fit.

Browse our full hardware collection — or contact us for help matching the right product to your door.