Smart locks differ mainly in how much door hardware they replace. A full deadbolt replacement swaps the lock, a retrofit add-on turns your existing deadbolt from inside, and a smart lever replaces a handle rather than a deadbolt.
This applies to standard exterior doors with a single-cylinder deadbolt, the most common smart lock target.
Does this affect you?
Use this if you want a smart lock but are not sure whether to buy a full deadbolt, retrofit lock, or smart lever.
The three main types
Each type has a real trade-off.
- Full deadbolt replacements, such as Schlage Encode, Yale Assure, and Kwikset Halo, replace the entire deadbolt and often include a keypad, app control, auto-lock, activity history, and a physical keyhole.
- Retrofit add-ons, such as August Wi-Fi Smart Lock or Level Lock, keep the existing exterior keyhole and deadbolt while adding motorized control inside.
- Smart levers or handlesets replace a handle or lever and are more common on interior, side, or secondary doors.
- Retrofit locks are best for renters or anyone who wants a reversible installation.
- Full deadbolt replacements are best when built-in keypad codes are a priority.
Retrofit locks are often easier to install and invisible from outside, but many need a separate keypad accessory if you want code entry.
What to check before buying
A smart lock must physically fit your door and deadbolt.
- Measure backset, the distance from the door edge to the center of the deadbolt hole.
- Check whether your backset is 2-3/8 inches or 2-3/4 inches and compare with the lock specs.
- Confirm the door uses a single-cylinder deadbolt with a keyhole outside and thumb-turn inside.
- Avoid assuming compatibility with double-cylinder deadbolts.
- Check battery type and expected life.
- Decide whether you need Bluetooth, Wi-Fi, Matter, or a hub.
- Choose a lock with a physical key or emergency backup.
Most smart locks use AA or CR123 batteries and do not need household electrical wiring.
Features and safety details
Keypad locks often support time-limited or one-time guest codes for cleaners, dog walkers, contractors, or visitors.
Check local fire and building rules for rental properties and multi-unit buildings, especially for exterior doors used as emergency exits.
Most smart locks warn about low battery before failing. Some keypad models include outside 9V contacts for temporary emergency power.
Auto-lock is useful, but test the delay so it does not lock while you are stepping outside briefly.
Sources
- August Home – Smart Lock Compatibility Guide (2025)
- Schlage – Choosing the Right Smart Lock (2025)
- Consumer Reports – Smart Lock Buying Guide (2025)