How to Measure Your Door Before Buying New Hardware

Finding the perfect door knob, lockset, hinge, or other piece of hardware is only half the battle. Before you place an order, there’s an equally important question to answer:

Will it actually fit your door?

Door hardware isn’t always one-size-fits-all. Door thickness, backset, bore holes, handing, and even the age of the door can affect which hardware will work. This becomes particularly important when you’re dealing with older homes, historic properties, commercial doors, or specialty hardware.

Before buying new door hardware, taking a few simple measurements can save you from ordering the wrong product—or unnecessarily modifying a perfectly good door.

1. Measure the Door Thickness

Start by measuring the thickness of the door itself. Measure from one face of the door directly across to the other.

Why does this matter? Knobs, levers, locksets, and other hardware are designed to accommodate specific ranges of door thickness. Hardware that’s too short or too long may not install or function correctly.

Never assume your door is a “standard” size, especially in an older building. Measure first.

2. Determine the Backset

If you’re replacing a knob, lever, or lock, you’ll also need to know the backset.

The backset is the distance from the edge of the door to the center of the hole where the knob, lever, or lock is installed.

This small measurement can make the difference between hardware that fits perfectly and a lockset that simply won’t work with your existing door.

3. Check the Existing Bore Holes

Modern doors are commonly prepared with pre-drilled holes for hardware, but older and custom doors can be an entirely different story.

Measure:

  • The diameter of the existing hole
  • The distance from the edge of the door
  • The size and shape of any opening along the door edge
  • The spacing between multiple holes, if applicable

If your door has a mortise lock, don’t assume that a new modern lockset can simply take its place. Mortise hardware is installed into a pocket within the door and requires different measurements.

4. Know Your Door’s Handing

Some hardware requires you to know whether your door is left-handed or right-handed.

Stand on the appropriate side of the door and pay attention to:

  • Which side the hinges are on
  • Which direction the door swings
  • Whether the door swings toward or away from you

Handing can become especially important with certain locks, levers, hinges, and specialty hardware.

If you’re unsure, don’t guess. Take a few pictures of the door from both sides and ask a hardware professional.

5. Don’t Forget About the Hinges

Replacing hinges involves more than finding something that looks approximately the same size.

You’ll want to consider:

  • Hinge height and width
  • Hinge thickness
  • Screw-hole placement
  • Corner shape
  • Door weight
  • Door material
  • How frequently the door is used
  • Whether a standard, pivot, concealed, self-closing, or specialty hinge is required

The wrong hinge can lead to sagging, poor alignment, difficulty closing, and premature wear.

What If You Have an Older Door?

This is where things can get interesting.

Older doors weren’t necessarily manufactured according to today’s standard dimensions. You may encounter unusual mortises, oversized backplates, uncommon hinges, discontinued locksets, or hardware that was made specifically for that building.

Don’t modify an original door until you know what you’re working with.

In many cases, the existing hardware can be restored. In others, an appropriate replacement can be sourced without drastically altering the door. And when a suitable product doesn’t exist, custom hardware may be an option.

Take Pictures Along With Your Measurements

Measurements are important, but pictures can be incredibly helpful when you’re trying to identify an unusual piece of hardware.

Before contacting us, consider taking photos of:

  • The front and back of the hardware
  • The edge of the door
  • Existing hinges
  • Lock mechanisms
  • Any manufacturer names, numbers, or markings
  • The entire door for context
  • If possible, place a ruler or tape measure in the photograph for scale.

When in Doubt, Ask Before You Buy

Door hardware can get complicated quickly, particularly when you’re working with antique doors, historic properties, unusual dimensions, or specialty applications.

That’s where experience matters.

At Door Hardware & Restoration, we work with a wide variety of door hardware, manufacturers, hinges, restoration projects, and hard-to-find pieces. If you aren’t sure what you need, give us a call.

Tell us what you’re working with, send us your measurements and pictures, and we’ll help you determine the right direction.

And remember: if you don’t see the hardware you need on our website, that doesn’t mean we can’t get it.

Sometimes finding the right piece simply starts with knowing who to ask.