Types of Door Locks: A Homeowner's Guide

"Lock" covers a lot of very different hardware. Knowing the main types helps you choose the right protection for each door — and understand what a locksmith is recommending.

Knob (cylindrical) locks

The lock built into a doorknob. Convenient and cheap, but weak on its own — the knob can be snapped or the latch slipped. Fine for interior doors; never rely on a knob lock alone on an exterior door.

Deadbolts

The workhorse of home security. A deadbolt throws a solid bolt deep into the frame. Single-cylinder (thumb-turn inside) is standard; double-cylinder (key both sides) adds security near glass but has fire-escape trade-offs. Look for ANSI Grade 1 for the strongest protection.

Lever-handle locks

Easy to operate — great for accessibility and common in offices. For exterior or secure doors, pair a lever set with a deadbolt.

Mortise locks

A heavy-duty lock that fits into a pocket cut into the door, common on older and commercial buildings. Strong and durable, but installation and repair are specialized work.

Smart & keypad locks

Electronic locks you open with a code, phone or fob. A smart lock adds remote access and guest codes; most are built on a deadbolt for real strength.

High-security & restricted-key locks

Brands like Medeco and Mul-T-Lock resist picking and drilling and use restricted keys that can't be copied at a hardware store. Ideal for high-value homes and businesses that need key control.

Which should you use where?

• Exterior doors: a Grade-1 deadbolt (traditional or smart), ideally with a reinforced strike plate.
• Interior doors: a knob or lever lock is fine for privacy.
• Businesses: levers plus deadbolts, mortise or high-security hardware, often on a master key system.
• High-value or high-risk doors: high-security, restricted-key locks.

Not sure what your doors have — or what they should have? Our residential and commercial locksmiths can assess your setup and recommend the right hardware.