What a keyway is and why it matters
A keyway is the shaped slot or opening inside a lock where the key fits. Every lock has one, and every key is cut to match a specific keyway shape. If your key doesn't fit the keyway, the lock won't open — even if you have the right key for that particular lock. Understanding what a keyway looks like and how to identify it is useful when you're replacing locks, ordering new keys, or troubleshooting why a key won't turn.
Keyways come in dozens of standard shapes, and each shape belongs to a lock manufacturer or a family of compatible locks. Knowing your keyway type tells you which keys will work, which blanks you can cut, and whether a locksmith can help you without replacing the entire lock.
Key Takeaways
- A keyway is the shaped opening inside a lock where the key slides in, and the shape determines which keys will fit.
- You can identify a keyway by looking at the key blank itself — the shape of the key's shaft shows you the keyway shape it was cut for.
- Common keyway shapes include round, square, and various patented profiles, each associated with specific lock brands or manufacturers.
- If you have the original key, you can take it to a locksmith or hardware store to match the keyway and order blanks or new keys.
- Keyway shape is separate from the key's cuts or bitting — two keys can have the same keyway but open different locks.
How to look at a keyway directly
The simplest way to see a keyway is to look straight into the lock opening with a flashlight. Shine the light into the keyhole and look at the shape of the opening. You'll see the outline of the slot — whether it's round, square, rectangular, or has other distinctive features like notches or shoulders.
If the lock is on a door or fixture you can't easily examine, or if the opening is too dark to see clearly, this method has limits. But if you have access and good lighting, a direct look tells you the basic shape right away. Take a photo if you can — it helps when you describe the keyway to a locksmith later.
Using the key itself to identify the keyway
If you have the original key, you don't need to look inside the lock at all. The key's shaft — the part that slides into the lock — is shaped to match the keyway exactly. Look at the key from the side and from the end. The outline you see is the keyway profile.
This is actually the most reliable method because the key is easier to examine than the lock. You can hold it up to light, measure it, photograph it, or show it to a locksmith. Many locksmiths can identify the keyway just by looking at the key blank, without needing to see the lock itself.
If you don't have the original key but you have a spare that works in the lock, that spare will show you the keyway shape too. Any key that fits the lock has the same keyway profile as the original.
Common keyway shapes and what they tell you
Standard keyway shapes fall into a few broad categories. A round keyway is circular and is common in older locks and some residential locks. A square keyway has a square or rectangular opening and appears in many modern residential and commercial locks. Patented keyways have distinctive shapes — notches, shoulders, or asymmetrical profiles — and are owned by specific manufacturers like Medeco, Schlage, or Kwikset.
Knowing the shape helps you understand which locks are compatible. If you have a Schlage keyway, for example, you can only use Schlage keys and blanks in that lock. If you have a round keyway, you might have more options because round keyways are used across multiple manufacturers, though the key cuts still have to match.
Some keyways are restricted, meaning blanks are not sold to the public — only to licensed locksmiths or the lock owner. High-security locks often use restricted keyways to prevent unauthorized key copying.
When you need to match a keyway to order new keys
If you want to order a new key cut from a blank, you need to know the keyway type. A locksmith or key-cutting service will ask you either to bring the original key or to describe the keyway. If you bring the key, they can match it directly. If you describe it, they'll ask about the shape, any visible brand name on the lock, and whether the key has any unusual features.
Hardware stores that cut keys can usually match a keyway if you bring the original key or a working spare. If you only have the lock and no key, a locksmith can identify the keyway by looking at the lock itself, but this takes more skill and may cost more than a straightforward key cut.
If the keyway is restricted, a locksmith may need proof of ownership or a registration card before cutting new keys. This is a security feature to prevent someone from making keys to a lock they don't own.
Keyway shape versus key cuts — why both matter
It's important to understand that keyway shape and key cuts are two different things. The keyway is the physical slot the key slides into. The key cuts are the notches filed into the key's edge, which align with pins inside the lock to allow it to turn.
Two keys can have the exact same keyway shape but completely different cuts — meaning they fit the same lock opening but open different locks. This is why you can't assume a key will work just because it fits into the keyhole. The cuts have to match too.
When you're ordering a new key, you need to provide information about both. The keyway tells the blank manufacturer which blank to use. The key cuts (usually identified by a code number from the original lock) tell them how to file the edges.
What to do if you can't identify the keyway
If you're stuck, a locksmith is your best option. Bring the lock itself, the original key if you have it, or both. A locksmith can identify the keyway by sight and can usually cut a new key or help you find compatible blanks. This service typically costs less than replacing the lock.
If you're trying to identify a keyway for a lock you've inherited or found, and you have no key, a locksmith can still help — they may be able to pick or manipulate the lock to determine the keyway type, though this takes more time and informed than matching an existing key.
Hardware stores are another option if the lock is a common residential brand. Staff can often identify keyways for Schlage, Kwikset, Master Lock, and other widely used manufacturers just by looking at the lock body or a photo.
Frequently Asked Questions
Can I use a key from one brand in a lock from a different brand if the keyway looks the same?
Not necessarily. While some manufacturers use similar keyway shapes, the key cuts are what actually open the lock. Two keys with the same keyway shape but different cuts won't work in each other's locks. Always test with the original key or a known working spare before assuming compatibility.
What's the difference between a keyway and a keyhole?
A keyhole is the opening you see on the outside of the lock. A keyway is the internal slot or channel inside the lock where the key actually slides. The keyhole is the entrance; the keyway is the path the key travels.
If I lose my key, can I just describe the keyway to get a new one cut?
A locksmith can cut a new key if you describe the keyway and provide the lock's code number (usually stamped on the lock body). However, it's easier and faster if you bring the lock itself or a working spare key. Without either, the locksmith may need to open the lock first to confirm the keyway type and cuts.
Are all round keyways the same?
Round keyways are similar in shape, but the exact diameter and any internal features can vary. Two round-keyway keys might look alike but have different cuts. Always verify that a key works before assuming it will fit based on keyway shape alone.
What does it mean if a keyway is restricted?
A restricted keyway means the blank is not sold to the general public — only to licensed locksmiths or authorized dealers. This prevents unauthorized copying and is common in high-security locks. If your lock has a restricted keyway, you'll need to work with a locksmith to get new keys made.