Three measurements tell you whether a lock will fit before you buy it.
Step-by-step guide
- Measure the backset Measure from the door edge to the center of the lock hole. It is almost always 2-3/8 or 2-3/4 inches.
- Measure the bore The large hole through the door face is normally 2-1/8 inches across. Older doors can be smaller.
- Measure the thickness Most doors are 1-3/8 to 1-3/4 inches thick. Thicker historic doors may need an extension kit.
- Check the edge hole and latch plate The hole in the door edge is usually 1 inch. Note whether the latch plate has square or rounded corners.
- Note the handing for levers Stand outside. Hinges on the left means a left-hand door. Some levers must match.
When to call a locksmith
If the steps above do not solve it, or you would rather not do it yourself, see Lock Change & Installation or browse more how-to guides.
Rather have it done for you? Mobile Locksmith DC is open 24/7 with a 15–25 minute response anywhere in Washington, DC. Call (240) 202-2249.