Mortise Cylinder Measurement & Sizing Guide
Printable Mortise Cylinder Measurement & Ordering Guide. Click to open and print at 100% scale.
Shop Replacement Mortise Cylinders
Use this guide to identify and measure an American-style mortise cylinder, match the cam, and choose the correct finish before ordering.
- Watch: Ordering and Installing a Mortise Cylinder
- Print the Mortise Cylinder Measurement and Ordering Guide at 100% Scale
Replace the Cylinder, Not Necessarily the Entire Lock
If the mortise lock mechanism and decorative trim still work, you can often replace only the keyed cylinder. Confirm the cylinder length, cam, keyway, and finish before ordering.
How to Order the Correct Mortise Cylinder
- Measure the length. Measure from the underside of the front flange to the back edge of the cylinder body. Do not include the cam.
- Match the cam. Compare the cam on the back of the old cylinder with the available cam options.
- Choose the finish. Select the finish that best coordinates with the existing trim.
Choose Your Length, Cam, and Finish
Mortise Cylinder Sizes
Most American mortise cylinders share the same threaded diameter (1-5/32", 32 threads per inch), so the length and cam are what change. Common lengths are 1", 1-1/8", 1-1/4", 1-3/8" and 1-1/2". Measure yours with the printable guide.
What is the standard size of a mortise cylinder?
The common size is 1-1/8" long with a 1-5/32" threaded body, but lengths vary with the door, the trim, and the rose. Always measure the old cylinder.
Are all mortise cylinders the same diameter?
Most American mortise cylinders are. European profile (euro) cylinders and rim cylinders are different and will not fit a mortise lock.
What is a turn knob mortise cylinder?
A turn knob (thumbturn) cylinder replaces a keyed cylinder on the inside of the door, so you turn a knob instead of using a key. It is a common upgrade on old double-keyed front doors. Shop the brass turn knob mortise cylinder or the Ilco turn knob cylinder with Adams Rite cam.
Can I replace a Baldwin lock cylinder?
Yes. Baldwin, Emtek and most designer mortise locks use standard mortise cylinders. Measure the length, match the cam and the finish, and order the replacement.
Mortise Cylinder Questions
How do I know whether I have a mortise cylinder?
A mortise cylinder has threaded sides and a short rotating cam on the back. A rim cylinder has smooth sides, two long mounting screws, and a long tailpiece. A tubular lock normally uses a separate latch and does not use this style of threaded cylinder.
Does door thickness determine the cylinder length?
Not by itself. The correct length also depends on the thickness of the rose or escutcheon around the cylinder. Measure the existing cylinder rather than ordering from door thickness alone.
Which cam do I need?
Match the replacement cam to the cam on the existing cylinder. The wrong cam can thread into the lock correctly and still fail to operate the lock.
Why will the cylinder not screw into the lock?
First make sure the cylinder retaining screw at the edge of the door has been backed out enough to clear the cylinder. Then start the cylinder squarely in the threads. Do not force it.
Why does my key stick or bind in a mortise cylinder?
Two common causes are a key that is cut slightly off and screws on the back of the mortise cylinder beginning to loosen. Check those before assuming the mortise lock itself has failed.
The cylinder retaining screw at the edge of the door holds the cylinder in position. It is not there to squeeze or pinch the cylinder.
How far should I screw the cylinder into the lock?
Thread it in until the face sits properly against the rose or escutcheon without projecting too far or sitting too deeply. Then secure the cylinder in position with the retaining screw.
Will this fit Baldwin, Emtek, or other designer hardware?
American-style mortise cylinders are used in many Baldwin, Emtek, Rocky Mountain Hardware, Sun Valley Bronze, Classic Brass, Accurate, and other locks. Brand alone does not confirm compatibility. Verify the cylinder length and cam before ordering.
Still uncertain? Send Classic Door clear photos of the existing cylinder, the cam, and the edge of the door with your measurements before ordering.