August Smart Lock Universal: Easy Deadbolt Retrofit

The August Smart Lock Universal (model AUG-SL05-M01-G01) is a retrofit smart deadbolt that fits over the interior thumb turn of your existing door hardware. Nothing on the exterior changes. Your old keys still work. It's a clean upgrade path for renters or homeowners who don't want to drill new holes or replace a deadbolt that's already doing its job, setup is easy and takes under 10 minutes.

What's in the Box and How It Installs

August ships the lock with a set of adapters sized for the most common US thumb turn shapes. Most people pick the right adapter in about 30 seconds. The installation guide on August's support site walks through each step with photos, and the August app mirrors this with a live setup flow.

Physical installation usually takes 10 to 15 minutes with a standard Phillips screwdriver. The adapter clamps onto the existing thumb turn, the lock body clicks on, and you're done with the hardware side. Then Wi-Fi setup runs through the app: Bluetooth pairing first for proximity configuration, then your 2.4 GHz network credentials. Note that 5 GHz is not supported, standard for battery-powered smart locks.

What You Get Out of the Box

• Lock body with mounting hardware and adapter set
• DoorSense magnetic sensor and adhesive mount
• 4 AA batteries (pre-installed)
• Quick-start guide

Connectivity and Platform Support

The lock runs Bluetooth for close-range use and Wi-Fi for remote access. Bluetooth handles auto-unlock as you approach, which keeps battery consumption lower day-to-day. Wi-Fi takes over when you need to lock or check status from across town.

Platform support covers the three major ecosystems without any additional hardware:

• Amazon Alexa: lock, unlock, and status via voice or routines
• Google Home: full lock control and automations
• Apple HomeKit: native support in the Home app, Siri commands, and HomeKit automations

Home Assistant users can add the lock via the August/Yale integration using their August account credentials. Lock state and lock/unlock actions appear as standard entities. It's cloud-dependent, but it works reliably once configured.

DoorSense

DoorSense is a small magnetic sensor that mounts on the door frame. It detects whether the door is physically open or closed, independent of deadbolt position. This matters for auto-lock: the lock won't throw the bolt if the door is ajar, which prevents a bent strike or a jammed deadbolt. Door status shows in the August app alongside lock state.

Auto-Lock, Auto-Unlock, and Guest Access

Auto-lock engages the deadbolt after a configurable delay ranging from 30 seconds to 30 minutes. It only fires when DoorSense confirms the door is closed, so a cracked-open door never gets an attempted deadbolt.

Auto-unlock uses geofencing combined with a close-range Bluetooth handshake. The app detects when your phone crosses the home boundary and queues an unlock, but the actual unlocking happens only when Bluetooth range is reached. This two-step approach cuts false unlocks from driving past the house.

Guest access is handled through virtual keys sent via the August app. You can set time-limited keys valid for specific dates and hours. They expire automatically, no need to remember to revoke access after a house guest leaves. The activity log records every lock event with a timestamp and the name of whoever triggered it.

Pros and Cons

Works well:

• True retrofit, exterior unchanged, existing keys still work
• Genuinely fast setup (under 15 minutes on most doors)
• DoorSense prevents auto-lock misfires
• Native HomeKit, Alexa, and Google Home without a hub

Worth knowing before you buy:

• Only works with standard US single-cylinder deadbolts, double-cylinder and European mortise locks aren't compatible
• 2.4 GHz only, same as most smart locks but worth noting if your router needs configuration
• Home Assistant support is cloud-based, not local
• The lock adds notable bulk to the interior side of the door

Who Should Buy This

The August Smart Lock Universal makes most sense for renters who need a lock they can install and remove without damage. It's also a solid choice for homeowners who want smart features without touching their exterior hardware or invalidating a door warranty.

If you're building a fully local smart home with no cloud dependency, this isn't the right fit. For that use case, a Z-Wave lock like the Schlage Encode Plus with a local hub gives you more control.

At $149, it sits in the mid-tier of the retrofit smart lock market. You're paying for the triple-ecosystem support and the no-hardware-change install story, both of which it delivers without compromise.

This review is based on hands-on use over several months, including testing auto-unlock reliability, guest access workflows, and Home Assistant integration. The lock held up well across all three areas with no unexpected lockouts or connectivity drops.

The Practical Verdict

The appeal here is simple: you keep your existing deadbolt, your keys, and your exterior hardware, and add app control plus auto-unlock in about fifteen minutes. That retrofit approach is what makes August worth considering for renters, who can pull the unit off when they move and leave the door exactly as they found it.

In daily use, the auto-unlock geofencing is the feature you'll notice most. It reads your approach and has the door open by the time you reach it, hands full of groceries. It misfires occasionally if your phone's location drifts, so I pair it with the in-app proximity check rather than trusting GPS alone. Battery life lands around six months on four AAs, and the app warns you well before the lock goes quiet. It isn't the cheapest smart lock, but the no-rekeying install keeps it relevant year after year.