Home locks
Door-lock backset: measure the right distance before ordering
Backset is the distance from the door edge to the center of the lock's main mounting hole. It is different from the distance between two locks on the same door. Measure using the prospective hardware's diagram and record the units. Common residential products support specified backsets, but an adjustable latch is not universal. Send measurements and door photos before ordering replacement hardware.
Locate the two reference points
Backset describes a relationship between the door edge and the center of the main lock opening. It does not describe the diameter of that opening or the spacing between a handle and deadbolt. Mark the measurement clearly in your notes so a retailer or installer knows which dimension you mean. A number without its reference points can look precise while answering the wrong fit question.
Read the selected product's range
Adjustable does not mean unlimited. For example, Schlage's Ganton keyed-entry specifications list support for the stated 2-3/8-inch or 2-3/4-inch backsets. That is a product-specific example of why the allowed positions matter; it is not a universal specification for every lock. Compare your door with the actual installation drawing for the product you intend to use, including any supported adjustment procedure.
Avoid measuring decorative trim
The outer edge of a rose or escutcheon is not the center of the lock bore. A large decorative plate can make an estimate from the visible hardware misleading. If the relevant center is obscured, send photographs and ask how the installer wants the dimension established. Do not remove unfamiliar hardware simply to obtain a measurement when the existing door still needs to remain usable and secure.
Consider an apparent near match
If your measurement falls between the product's stated positions, do not round it to whichever option looks closer and order on that basis. Recheck where the tape began, whether it crossed the correct center and whether the door edge geometry affects the reading. An installer may need to assess the existing preparation. A small-looking discrepancy can be more meaningful than the size of the visible trim suggests.
Plan the purchase around the complete preparation
Backset is one item in a broader fit record that also includes door thickness, bore dimensions and any additional attachment points. Keep these measurements separate and label photographs with the opening identifier. For a Sacramento home hardware update, sharing that record before parts are ordered can make the proposed installation clearer. The final decision should match the whole door preparation, not just one familiar residential dimension.
Before you call
- Label the door edge and bore center in the measurement record.
- Compare against the exact product's permitted backset positions.
- Review the remaining preparation dimensions before ordering.
Follow-up questions
Does a matching backset prove a smart lock will fit?
No. Door thickness, openings, spacing, trim clearance and the product's other requirements still need review. Backset resolves one fit question, not the complete installation.
Should I measure from the outer edge of the decorative rose?
No. Use the reference points in the selected product's preparation diagram. If the bore center is hidden, ask the installer how to establish it accurately.
Official reference
Schlage: Ganton keyed-entry specifications ↗
A named example of backset, thickness and latch options. Its dimensions apply to this product, not all door hardware.
Published by AID Locksmith, owned by Allan, serving Greater Sacramento. General service checklists are editorial guidance; product instructions apply to the named model.