How to Measure a Lock for a Door

How to Measure a Lock for a Door


Measuring a lock for an internal or front door can be a daunting task but it doesn’t have to be. The process is quite simple and doesn’t take any education or knowledge of construction to do it properly.

Before you get started, certain terms are helpful to understand so that you can follow the instructions. According to Maria from Doors Galore “This is often what discourages people from attempting this simple process. If the instructions contain words that are confusing and unfamiliar, this is where people quit.”

Door Hardware

The term for handles, locks, and any equipment that is being installed.


Backset is the distance from the center of the hole that the doorknob or lock sits in to the edge of the door. It describes how far the center is set back from the edge of the door.

Bore Hole

Borehole is the hole that the doorknob or lock rests in.

Cross Bore

Cross bore is the hole that allows the door latch or dead bolt (which is moved in and out by the handle) to connect with the door frame, where it keeps the door closed.

Lock Spacing

Lock spacing describes the space between the doorknob and the lock or two different locks. In residential, it most commonly refers to the space between a doorknob and the deadbolt.

Door Jamb

A door jamb is the area where the latch from the door handle goes into the door frame, allowing it to stay closed.

Steps to Measure a Lock

1. Measure the diameter of the borehole that is currently in your door for the lock and handle. You will need this measurement to choose the proper door lockset.

2. If you are removing the entire doorknob/ lockset, remove the handle to double-check the size of the borehole under the knob. They are typically 2 1/8” but can vary in older homes.

3. Measure the backset of the knob and the lock. This is the distance from the edge of the door to the center of the hole. Most doors are either 2 3/8” or 2 3/4” for the handle and lock. Check your lock spacing as well to make sure that your new set will fit.

4. Check the thickness of the door. Most modern hardware accommodates 1 3/8” or thicker doors. If your door is thinner, you may need a thickness plate or door reinforcer to fit the lock and handle.

5. With the correct measurements, you can purchase a lock and handle set that matches your backset and door thickness. Once you have these, follow the installation instructions that come with the hardware, making sure to follow each instruction carefully.

On to the Next Step!

Now that you have all the measurements ready, you can proceed with changing out the lockset on your doors. Taking on the task of measuring and changing out the lock and handle of your doors can be fun and exciting. It can also save you some money by taking on the project yourself.

Whether you wanted to save some money or are looking to improve your DIY skills, learning how to measure a lock for your doors and change them is a great way to do it.