Which Key Do You Have? Identify KW1, SC1 and SmartKey in 60 Seconds

Most San Diego homes run on one of two house keys: Kwikset’s KW1 or Schlage’s SC1. Knowing which one you hold answers half the questions people ask us: can these doors go on one key, will this smart lock match, and can that odd back door join the rest. You can tell in about a minute with the key in your hand.

Step 1: read the bow of the key

The bow is the wide head you hold. On most residential keys it is stamped with the brand: Kwikset, Schlage, Weiser, Baldwin, Yale. Hardware-store copies often carry the blank maker’s name instead, with a small code such as KW1 or SC1 somewhere on the bow. Either way, the bow is the fastest tell.

No stamp, or a worn one? Go to the blade.

Step 2: compare the blade and the keyway

Hold the key with the cuts facing up and look at the end of the blade, or look straight into the keyway on the lock.

Kwikset KW1

The KW1 keyway is wider and more squared than Schlage’s, and the blade matches: a broader, flatter profile with a fairly plain outline. It has five pin positions. It is the most common residential keyway in the US, and it is what most builder-grade hardware in newer tract homes uses, which is why so many doors in 4S Ranch and the other master-planned communities take the same key blank.

Schlage SC1

The SC1 keyway is narrower and has a distinctive curve to it; the blade has a matching wavy profile you can feel with a fingertip. Five pins as well. Schlage residential deadbolts and handlesets use it, and so do several smart locks.

Put a KW1 and an SC1 side by side and the difference is obvious. One is broad and square, the other narrow and curved. Neither will enter the other’s lock, no matter how it is cut.

Step 3: look for the SmartKey slot

Now look at the face of the lock. On a Kwikset SmartKey cylinder there is a small rekey hole just beside the keyway, about the width of a paperclip. That is where the learn tool goes.

A standard SmartKey cylinder uses the ordinary KW1 key. What changes is inside: sliders instead of pins, which let the lock learn a new key in a minute when you have a working key and the tool. Full steps are in How to Rekey a Kwikset SmartKey Lock. Two things follow from that design. A SmartKey lock and a plain Kwikset lock can share a key. And a SmartKey lock cannot be master keyed, so it cannot join a building’s master key system.

No slot, and a Kwikset bow? A conventional pin-tumbler Kwikset cylinder. It rekeys the traditional way, with pins, and our Kwikset SmartKey page explains how the two versions differ on a service call.

Brand by brand: keyway, rekey and keyed alike

Which smart locks use which keyway?

This is where the keyway decides your shopping list. Schlage Encode and Encode Plus carry an SC1 cylinder and match a Schlage house. Kwikset Halo carries SmartKey on KW1 and matches a Kwikset house. The keyed Yale Assure Lock 2 also uses KW1, so it matches Kwikset doors too, which surprises people. The Level Lock+, Level’s earlier Home Key model, uses a Schlage-style five-pin cylinder and sits with the Schlage group. August and Level Bolt keep whatever deadbolt is already on the door.

If you want one key for every door, choose the smart lock from the group your house already belongs to. Can a Smart Lock Be Rekeyed? goes through each model, and our Schlage, Yale, Kwikset and Level pages list what we install.

Why does the keyway matter?

Because rekeying works within a keyway, not across one. A locksmith can set any KW1 lock to any KW1 key, and any SC1 lock to any SC1 key, but a standard Kwikset cylinder will never take a Schlage key. The fix is a cylinder in the right keyway, and Kwikset now sells a SmartKey cylinder in SC1 for that. That is the whole basis of a keyed alike rekey: every lock in the set has to share a keyway first.

It also decides whether a building can be master keyed. Conventional pin-tumbler cylinders can. SmartKey cannot.

What if the house mixes brands?

Very common in older neighborhoods. A mid-century home in La Mesa might have a Schlage front door from one remodel, a Kwikset back door from another, and an off-brand knob on the garage entry. Three keys on the ring.

The fix is a cylinder swap, not three new locks. The locksmith keeps the majority keyway, replaces the cylinder (or, where the design does not allow a cylinder swap, the lock) on the odd door, and keys the whole set alike. Our lock replacement page covers the swap; Rekey vs. Change Locks explains when a swap beats a full replacement.

Send a photo of the key bow with your quote

The quickest way to get an accurate quote is a photo. Lay every key you use on a table, bows up, and take one picture, plus one of the face of each lock. That tells us the keyways, whether SmartKey is involved, and how many cylinders the job has, before we arrive. Send it through the quote form.

When to call

Call when the keys are mixed and you want one key, when the bow is worn and the keyway is unfamiliar, when a less common keyway is involved, when a SmartKey lock has stopped accepting keys, or when you are choosing a smart lock and want it to match the house.

Next step

If a smart lock’s override key is the one you cannot place, or the lock is acting up as well, book smart lock repair and troubleshooting and we will identify the keyway, rekey the override to your house key and sort out the lock in one visit. For plain locks on one key, the keyed alike service is the place to start.