How To Determine Backset for Door Hardware
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Backset is a crucial but often overlooked measurement when choosing door hardware. This guide explains what backset means, how to measure it, and why it matters for both standard and mortise locks. Learn how to find the right fit for your doors and avoid common installation mistakes!
When selecting door hardware, one of the most important but often overlooked measurements is the backset. Choosing the correct backset ensures that your door latches and locks function properly while maintaining a seamless look. In this guide, we’ll break down what backset means, how to measure it, and why it matters when selecting door hardware.
Note: The backset measurement refers to the placement of the borehole for the latch or lock—it does not correspond directly with the width or thickness of the door itself.
What is Backset?
The backset is the distance from the edge of the door to the center of the borehole (the hole where the lock or latch is installed). This measurement is crucial in ensuring that your chosen hardware fits and operates correctly.
Most residential doors in North America use one of two standard backset sizes:
- 2-3/8 inches (60mm) – Common in interior doors and some exterior doors.
- 2-3/4 inches (70mm) – Typically found in commercial doors and high-security exterior doors.
Some specialty doors, like older or custom-built ones, may have a non-standard backset, so it’s always best to measure before purchasing.
How to Measure Your Door’s Backset
Measuring the backset is simple and only takes a few steps:
Locate the Borehole – Find the hole drilled into the face of your door where the handle or lock will be installed.
Measure from the Edge – Using a tape measure, find the distance from the edge of the door to the center of the borehole.
Note the Measurement – If your measurement is around 2-3/8″ or 2-3/4″, you have a standard backset. If it’s different, you may need specialized hardware.
Mortise Backsets
If your door uses a mortise lock, the backset measurement works a little differently. Mortise locks are typically found on older homes, high-end doors, and commercial applications. Instead of a standard latch and borehole setup, a mortise lock requires a pocket (or “mortise”) to be cut into the door.
Common mortise lock backset sizes include:
- 2-1/2 inches (64mm) – A standard size for many residential and commercial mortise locks.
- 2-3/4 inches (70mm) – Common in commercial applications and some high-security locks.
- Other sizes – Some manufacturers offer unique backset sizes, so always verify before purchasing.
Measuring a mortise backset follows the same principle—measure from the door’s edge to the center of the key cylinder or thumb turn.
Why Does Backset Matter?
Choosing the wrong backset can result in:
✔ Misaligned Latches & Locks – The latch won’t properly align with the strike plate, affecting security and function.
✔ Aesthetic Issues – Handles or locks may look off-center on the door.
✔ Installation Challenges – Hardware might not fit properly, requiring modifications.
Many door hardware brands offer adjustable backsets, which means the latch can be set to either 2-3/8″ or 2-3/4″. If you’re unsure which backset you need, an adjustable option may be the best choice.
Final Thoughts
Backset is a small but essential detail that ensures your door hardware functions and looks perfect. Whether replacing a handle, installing a new lock, or upgrading your doors, measuring the backset first will save time and frustration.
Need help choosing the right door hardware? Our team is happy to assist—contact us today!