EN 1303: The European Standard for Lock Cylinders

Status and Editions

According to the 2026 text's European foreword:

• EN 1303:2026 was approved by CEN (the European Committee for Standardization) on February 9, 2026, and carries the date May 2026.
• It supersedes EN 1303:2015.
• It was prepared by CEN Technical Committee 33 (doors, windows, shutters, building hardware and curtain walling). ARGE, the European federation of lock and builders' hardware manufacturers' associations, collaborated in the drafting.
• National standards bodies must adopt it, and withdraw conflicting national standards, by November 2026 at the latest. The foreword lists the CEN member countries bound to do so, including the United Kingdom.

In the UK, BSI lists BS EN 1303:2026 as current, published August 31, 2026, and BS EN 1303:2015 as withdrawn. The 2015 edition had itself replaced a 2005 edition.

What EN 1303 Covers

The 2026 scope says the standard applies to "cylinders and their keys for such locks as are normally used in buildings," where the lock has an operational torque of no more than 1.5 Nm. It sets requirements for "strength, security, durability, performance and corrosion resistance of cylinders and their original keys," and, new in 2026, for cylinders used in locking systems and master key systems.

The introduction adds two limits worth knowing:

• The test methods aim to keep "human influence on the test results to a minimum."
• The standard "does not specify any particular design or installation." It tests performance; it does not prescribe a mechanism.

The Eight-Digit Code

An EN 1303 classification is written as eight digits, one for each property. The 2026 table of contents gives the order:

The standard defines a cylinder as a "device, usually distinct from its associated lock or latch, operated by a key." For terms such as plug and keyway, see the glossary.

Key-Related Security (Digit 7)

The seventh digit is graded on how the cylinder is designed, not on a timed attack. The 2026 table of contents lists the criteria:

• Minimum number of effective differs (distinct key combinations)
• Minimum number of active movable detainers (pins, discs, or similar elements the key must set)
• Maximum number of identical steps
• Whether the key carries a "direct code," a marking that reveals its coding without looking it up elsewhere
• Operation of the security mechanism ("interpassing"), and torque resistance of the plug
• Manipulation resistance, with requirements and evaluation methods added in 2026

Industry summaries of the 2015 edition describe grade 6 as the highest key-related security grade. The exact 2026 threshold values were not in the portion of the text we could read, so this article does not give them.

Attack Resistance (Digit 8)

The eighth digit records resistance to destructive attack. The 2026 text lists five test areas: drilling, chisel, twisting, plug or cylinder extraction, and torque on the plug or cylinder. BSI's summary of the 2015 changes shows that the grades are not all the same test at different durations. Plug-extraction requirements were added at the upper grades (C with a 10 kN pull, and D), while grades A and B have no extraction test.

The test descriptions are laboratory procedures. They are not a prediction of how long a cylinder will last against a real attack, and this article does not describe attack methods.

What Changed in 2026

The 2026 foreword lists these significant technical changes from the 2015 edition:

1. Scope extended to cylinders used in locking systems
2. New Annex F for cylinders in locking systems
3. Definitions related to master key systems added (master key, grand master key, sub-master key, central locking system, lock chart)
4. Requirements and evaluation methods for manipulation added
5. Digit 3 changed from door mass to mechanical coding
6. Definition of pulling screws changed, with a new normative Annex G
7. Figures renumbered

Because digit 3 changed meaning, a code printed on a cylinder tested to the 2015 edition should be read against that edition. The marking should name the edition.

The introduction also points to a separate document, CEN/TS 17814, for protecting data and sensitive information about mechanical master key systems. See master keying and key control.

Fire and Smoke Doors

Fire suitability is optional. The introduction says the manufacturer "has the option to state" whether a cylinder conforms to Annex A. The scope says suitability for fire or smoke door assemblies is determined by fire tests "in addition to" the EN 1303 performance tests. As with any fire-rated opening, the authority having jurisdiction decides what may be installed. See fire-rated door hardware.

EN 1303 and American Standards

EN 1303 grades do not map directly onto American ratings. In the United States, cylinders are described under ANSI/BHMA A156.5 (cylinders and input devices), ANSI/BHMA A156.30 (high-security cylinders), and UL 437 (key locks). Each uses its own tests, categories, and thresholds. A cylinder marketed in both regions needs to be checked against each standard separately. See ANSI/BHMA lock grades, UL 437, and high-security locks.

Related Topics

• Euro cylinders: the cylinder format most often classified under EN 1303
• High-security locks: how security ratings are used
• ANSI/BHMA lock grades: the U.S. grading system
• UL 437: U.S. attack-resistance listing for key locks
• Master keying: now within EN 1303's scope
• Key control: who holds and copies keys
• Fire-rated door hardware: fire door context
• Keyed alike: the KA term used in digit 3
• Disc detainer locks

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