How to Identify a Replacement Window Key
Lost or damaged window keys can often be replaced without changing the handle or lock. Many uPVC and double-glazed window locks use pre-cut replacement keys, but similar-looking keys are not always interchangeable. Use the steps below to identify the correct replacement.
1. Check the window handle and lock for a manufacturer
Look closely at the handle, lock casing and faceplate for a manufacturer’s name or logo. It may be printed, engraved or moulded into the surface.
Common manufacturers include:
- WMS
- Chubb
- ERA
- Winlock
- Securistyle
- Titon
- Cotswold
- Mila
- Basta
- Roto
- Avocet
- Yale
The manufacturer is one of the best starting points, although some manufacturers have produced several different key shapes.
2. Look for a reference number
Check the key, window handle and lock for letters or numbers. A reference might be printed on the key head, stamped into the metal or shown near the keyhole.
Compare the complete reference carefully. A small difference in the number can indicate a different key profile.
3. Compare the shape of the key
Place your existing key—or a key from another matching window—next to the product photographs. Check:
- The overall shape of the key head
- Whether the blade is flat, round, square or hexagonal
- The number and position of notches
- Whether the key is single- or double-sided
- The shape of the key tip
- Any holes, grooves or raised sections
- The length of the blade
Do not rely only on the colour of the plastic head. Different keys can use very similar colours and designs.
4. Identify what the key operates
Confirm whether the key is intended for a:
- Window handle
- Window lock
- Window bolt
- Window restrictor
- Tilt-and-turn window
- Casement or sash window fitting
Keys designed for different lock types can look similar but may not operate the same mechanism.
5. Measure the key where possible
If you still have an original key, measure its blade length and width. For square or hexagonal keys, measure the section across the flat sides.
Even a small difference can prevent a key from entering or operating the lock correctly.
6. Check another window in the property
Windows installed at the same time often use matching handles and keys. If one key has been lost, try to find an original from another window and compare it with our photographs and measurements.
Never force a key into a lock. If it does not enter or turn smoothly, remove it and check the profile again.
Shop by Manufacturer
Browse our replacement window keys by manufacturer:
Still Not Sure Which Key You Need?
If you cannot identify your window key, contact Thunderfix Hardware with clear photographs of:
- The key, if available
- The front and back of the window handle
- The keyhole
- Any manufacturer name or reference number
- A ruler beside the key or keyhole for scale
Providing these details will make it easier to identify a suitable replacement.
