DIY Basics & Home Maintenance · 7 min read · Beginner

How to Measure & Change a Euro Cylinder Lock

Measure a Euro-profile cylinder from its fixing-screw centre, choose the correct internal/external lengths, and replace a straightforward cylinder without disturbing the whole lock case.

Key points & steps

  1. Confirm that the door really uses a Euro-profile cylinder and that the multipoint lock, handles and door alignment are otherwise working normally.
  2. With the door open, locate the long cylinder retaining screw on the door edge in line with the cylinder.
  3. Measure from the centre of that retaining screw to the outside face of the existing cylinder or handle/escutcheon, then repeat from the centre to the inside face. Record the two dimensions separately, for example 35/45 mm rather than only the overall length.
  4. Avoid choosing a cylinder that projects unnecessarily beyond the protective handle or escutcheon. The correct size should suit the actual door and security furniture.
  5. To remove a straightforward cylinder, open the door, remove the retaining screw, insert the key and turn it slightly until the cam lines up with the cylinder body, then withdraw the cylinder gently.
  6. Insert the replacement in the same orientation, confirm the cam operates freely, refit the retaining screw without overtightening and test the lock several times with the door still open.
  7. Finally test the door closed. If the mechanism is stiff only when the door is closed, alignment may be the real issue rather than the cylinder.

Practical tips

  • Measure the actual door rather than relying on a cylinder stamped size if you are not certain how it was specified.
  • For an external door, consider a cylinder with recognised anti-snap/anti-drill security certification and compatible protective door furniture.
  • Never force a cylinder or multipoint mechanism. If the key, cam or gearbox feels abnormal, stop before creating a lock-out situation.

What you may need

  • Tape measure or ruler
  • Suitable screwdriver
  • Replacement Euro-profile cylinder
  • Existing key

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