Lock Grades Explained

Lock grades come from the ANSI/BHMA A156 series of standards. BHMA (the Builders Hardware Manufacturers Association) writes the tests and ANSI (the American National Standards Institute) approves them. Independent labs then test locks for durability, strength and finish. The biggest difference between grades is the cycle test: how many times the lock is opened and closed on a test rig before it must still work properly. Higher grades also face tougher strength tests, such as door strikes and torque on the lever.

Two things to watch for on packaging:

• “Grade 1 deadbolt” is not the same as a Grade 1 lock. Sometimes only one part of the product, such as the bolt, carries the rating.
• “Equivalent to Grade 1” or “meets Grade 1 standards” usually means the product was not independently certified. Look for “ANSI/BHMA certified”.

Grade 1 vs Grade 2 vs Grade 3

Cycle figures are for bored (cylindrical) locks under ANSI/BHMA A156.2. Other lock types, such as deadbolts and mortice locks, are tested under different A156 standards with different figures.

In practice, cycle counts matter less in a home than in an office. Even a Grade 3 lock will outlast years of family use. The strength tests are the more useful guide to how well a lock resists force.

How Australian lock ratings compare

Australia has its own standard: AS 4145.2, Mechanical locksets for doors and windows in buildings. Instead of one overall grade, it rates a lock separately on:

• Physical security (S levels): resistance to forced attack. Higher numbers mean more resistance.
• Durability (D levels): how much use it is built for.
• Keying and cylinder security: how well the cylinder resists manipulation and how tightly key copying is controlled.
• Corrosion resistance: useful for exposed doors.

You will see these on Australian brand data sheets, for example a mortice lock rated S7 and D7. The two systems do not convert neatly, so compare like with like: grades against grades, S levels against S levels.

A locksmith can read the data sheet and tell you how a lock will perform on your particular door.

Which grade for which door in an ACT home

A few Canberra-specific points:

• Older homes. Many homes in suburbs like the inner north and Woden Valley have original timber frames. A high-grade lock needs a solid strike plate and longer screws into the frame to deliver its rating.
• Seasonal movement. Timber doors shift between frosty winters and dry summers. A lock that drags in July needs adjustment before it wears out.
• Rentals. Tenants should get the landlord’s written consent before upgrading a lock. Security upgrades get extra protection under ACT tenancy law; see our smart lock pros and cons guide.

Get the right grade fitted

Our Canberra residential locksmiths can check your doors and frames and fit a lock with the right rating. Browse our lock products for Canberra homes to compare deadlocks, mortice locks and smart locks by rating.

Related guides: Mechanical vs smart locks · Smart lock pros and cons