About LockSpecs
LockSpecs is a free reference site for working locksmiths, apprentices and facility managers who deal with interchangeable cores and master key systems. It has one job: turn published manufacturer specifications into calculators and charts you can use on the job — and show you where every number came from.
The calculators run entirely in your browser. There is no account, no sign-up and nothing to install. The site is static: once a page has loaded, the math happens on your device.
Where the numbers come from
Every specification value on this site — stack totals, control constants, increments, pin lengths, depth ranges — is taken from a manufacturer document and checked against at least one other source before it is published. Values that cannot be sourced are not shown. For example, we do not apply a MACS (maximum adjacent cut) limit to SFIC systems, because none of the manufacturer documents below state one.
The SFIC pinning calculator and chart are based on:
- SARGENT Small Format Interchangeable Core — Keying & Assembly Manual (Rev. March 2006)
- Schlage small format cores — Service manual 108230 (Rev. 01/18)
- Schlage SFIC Service Manual, Second Edition (June 2000)
Where sources disagree, we say so. The 2018 Schlage manual lists the A2 #9 bottom pin as .225"; the 2000 Schlage edition, the Sargent manual and the regular .0125" progression all give .2225", which is the value we use.
The calculator's results are also tested against the worked example in the Schlage manual and against an independent third-party calculator. That said, it is a reference tool: always confirm a pinning against your own key gauge and the manufacturer's current documentation before you build a core.
What LockSpecs does not do
- No lock picking, bypass or defeat instructions.
- No key code to bitting lookups. The calculator only works from bittings you already have.
- No collection of the bittings you enter. They never leave your browser — see the privacy policy.
- No affiliation with any lock manufacturer, and no locksmith services.
How the site is funded
LockSpecs is free to use. It currently carries no ads and no affiliate links. If that changes, affiliate links will be labelled next to the links themselves, and the calculators will keep working the same whether or not you click.
Found an error?
A wrong number on a pinning site costs someone a rebuilt core, so corrections are the most useful thing you can send. Email contact@lockspecs.com with the page, the value you believe is wrong, and the document you are reading it from. Please do not include real key bittings from a live system in your email.