How to Identify Your Key Type: Cylinder, Mortice & Padlock Keys Explained

Why Identifying Your Key Type Matters

Ordering the wrong key blank is one of the most common mistakes people make when replacing a lost or worn key. Before you buy, it's worth taking 60 seconds to identify exactly what type of key you have — it'll save you time and money.

At Thunderfix Hardware, we stock a wide range of key replacements and can cut keys to order. Here's how to work out which type you need.

Cylinder Keys (Yale-Style Keys)

Cylinder keys are the most common type of door key in the UK. They're used with rim locks and euro cylinder locks — the kind you'll find on most front doors.

How to identify one:

• Flat, single-sided blade with a series of cuts along one edge
• Small, rounded bow (the part you hold)
• Often stamped with a brand name like Yale, ERA, or Chubb

If your lock has a round barrel that turns when you insert the key, you almost certainly have a cylinder lock. Browse our rim cylinders and euro double cylinders if you need to replace the lock itself.

Mortice Keys

Mortice keys are used with mortice locks — the type that sits inside (morticed into) the door. They're common on older properties and internal doors.

How to identify one:

• Larger, heavier key with a round or oval bow
• A long, flat shank with a bit (the shaped end) that engages the lock mechanism
• Often made of brass or steel
• May have a number stamped on the bow (e.g. M1, MH1) — this is the key series

The number or series stamped on your key is the most reliable way to find the right replacement. Browse our mortice key blanks and pre-cut mortice keys — or if you know your series, check our Union MH Series pre-cut mortice keys.

Padlock Keys

Padlock keys vary widely depending on the brand and model of padlock. They're typically smaller than door keys and may look similar to cylinder keys but with a different profile.

How to identify one:

• Small, compact key — often with a round or D-shaped bow
• Brand name or model number may be stamped on the padlock body (not always on the key)
• Some padlocks use a code stamped on the lock shackle

If you have the padlock but not the key, check the body of the padlock for a key number or code — this is often all we need to cut you a replacement. Browse our padlock keys or padlocks if you need a full replacement.

Furniture & Specialist Keys

Beyond door and padlock keys, there are many specialist key types — including furniture keys for cabinets and drawers, window keys, utility keys for meters and service panels, and radiator bleed keys.

If you're unsure what you have, the easiest approach is to send us a photo — see our guide on how our cut-a-key-from-photo service works.

Still Not Sure? We Can Help

If you can't identify your key from the descriptions above, don't worry. Our key cutting service is here to help — just get in touch and we'll do our best to identify it from a photo or description.

You can also browse our full key replacements collection or use our keys cut to code service if you have a key code but no key.

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