The number of distinct cuts (the peaks and valleys) along the blade of your key tells you how many pins are in the lock. Each cut corresponds to one pin, so a key with five cuts means five pins, and a key with six cuts means six pins. Most residential locks use five or six pins, though some use as few as four or as many as seven.
Counting the Cuts on a Standard Key
Hold your key with the blade facing up so you can see the jagged edge clearly. Each valley, or low point, carved into the blade represents one pin position inside the lock. Count every distinct cut from the shoulder (the square step where the blade meets the wider bow) all the way to the tip. That number is your pin count.
Some cuts may be very shallow, making them easy to miss. Run your finger slowly along the bitting and feel for each change in height. Even a slight dip counts as a separate pin position. A cut that sits nearly flush with the top of the blade simply means that pin is set to its shallowest depth, not that it’s absent.
One common mistake is counting peaks instead of valleys. Peaks are just the transitions between cuts. If you count valleys (the low points), you’ll get the correct number every time.
Key Length as a Quick Visual Clue
Pin chambers inside a lock are drilled at evenly spaced intervals along the plug. That means a six-pin key is physically longer than a five-pin key for the same brand, because it needs room for an extra cut. If you place a five-pin and six-pin key from the same manufacturer side by side, the difference in blade length is obvious, usually a few millimeters.
This makes blade length a useful shortcut when you can’t easily distinguish individual cuts. A noticeably longer key from the same lock brand almost certainly has more pins. Kwikset and Schlage residential keys, for example, are typically five-pin, while their six-pin versions have a visibly longer blade with one additional cut near the tip.
The Shoulder and Where Cuts Begin
The shoulder of a key is the small ledge that stops the key at the correct depth when you insert it into the lock. Pin spacing is measured from this shoulder to the center of the first cut, then at regular intervals from there. Knowing this helps you identify the first cut accurately, especially on keys where the first cut sits close to the shoulder and might look like part of the key’s profile rather than a deliberate pin position.
Some keys, particularly for padlocks and certain commercial cylinders, are “shoulderless,” meaning they lack that square stop and instead use the tip of the key as the reference point. On these keys, cuts are spaced starting from the tip. The counting method is the same: count every valley along the blade.
Double-Sided and Wafer Lock Keys
If your key has cuts on both the top and bottom edges, it likely operates a wafer lock rather than a pin tumbler lock. Wafer locks use flat metal pieces instead of round pins, and the key’s bitting on each side corresponds to a separate set of wafers. You’ll find double-sided keys on many car doors, filing cabinets, and desk locks.
To count wafer positions, you need to count the cuts on both sides of the blade. A key with four cuts on top and four on the bottom operates eight wafers total. The counting technique is the same as with pin tumbler keys: count every distinct valley on each edge.
Dimple Keys Work Differently
Dimple keys look nothing like standard keys. Instead of a jagged edge, they have a flat blade with small circular indentations (dimples) drilled into one or both flat faces. These keys operate high-security pin tumbler locks, and each dimple corresponds to one pin.
Counting pins on a dimple key means counting every dimple on the blade’s surface. Some dimple keys have pins in multiple rows or on both sides of the blade, so flip the key over and check both faces. A key with three dimples on the front and three on the back operates six pins. The varying depths of those dimples work exactly like varying cut depths on a standard key, setting each pin to the correct height.
What the Pin Count Tells You
More pins generally means more security. A five-pin lock is standard for most homes. Each additional pin multiplies the number of possible key combinations, making the lock harder to pick and reducing the chance that a random key could open it. A six-pin lock offers roughly ten times more possible combinations than a five-pin lock of the same brand, assuming the same number of depth increments per pin.
Four-pin locks appear on lower-security applications like interior doors, luggage, and some padlocks. Seven-pin locks are less common but show up in commercial and high-security settings. If you count seven cuts on your key, you’re dealing with a lock designed to resist manipulation.
Knowing your pin count is also practical if you need a locksmith to rekey your lock or if you’re buying a replacement cylinder. Matching the pin count ensures compatibility with your existing keys.