A deadbolt that locks itself solves one specific failure: the door you pulled shut on your way to work and never thought about again. The mechanism behind that is simpler than most people expect, and it comes down to two triggers — a clock, or a sensor that knows the door just closed. August builds both into its smart locks, and the difference between them decides how the lock behaves in daily use.
Here is the part worth understanding before you buy anything: an automatic locking deadbolt is not a new kind of lock. It is a standard deadbolt with a motor and a control module attached, watching for the moment to throw the bolt for you.
What Actually Happens Inside The Lock
August’s smart locks attach to an existing single-cylinder deadbolt on the inside of the door, which means the exterior lock and your original keys stay fully usable.
That design detail matters more than it sounds. The outside of your door looks unchanged — same keyway, same key. Everything smart happens on the interior side, where a motor turns thethumbturn the way your hand would. The lock is installed on the inside of the door and August says it takes minutes, since nothing is drilled or replaced.
A single-cylinder deadbolt is the requirement. That is the standard configuration on most US entry doors: key on the outside, thumbturn on the inside. Non-standard or multi-point deadbolt setups may not fit this product category, so it is worth checking your door before ordering.
Timer Or Door Sensor? The Two Auto-Lock Modes
August supports two ways for the bolt to throw itself: a countdown timer, or instant locking the moment the door closes — and the instant mode only works if DoorSense is installed.
The timer mode lets you set a delay, anywhere up to 30 minutes, before thelock engages on its own. The door can still be open when the countdown starts, so a long timer is less about security than about convenience.
The instant mode is the one that behaves like a true automatic locking deadbolt. August’s DoorSense is a small sensor that reports whether the door is open or closed. When it detects the door changing from open to closed, the lock engages right away. No countdown, no gap where the door sits shut but unlocked.
| Auto-Lock Mode | Trigger | DoorSense Needed |
|---|---|---|
| Timer Auto-Lock | Countdown, up to 30 minutes | Required for timing feature |
| Instant Auto-Lock | Door closes | Yes |
| Manual (Auto-Lock off) | You turn the thumbturn | No |
Without DoorSense installed or calibrated, the close-based behavior simply is not available — timer-based auto-lock is the only option left.
How To Turn Auto-Lock On Or Off
Auto-Lock is configured entirely in the August app, and you need to be an authorized owner within Bluetooth range of the lock to change it.
- Open the August app and tap your home.
- Go to Lock Settings and choose the lock you want to adjust.
- Tap Auto-Lock, then toggle Enable Auto-Lock.
- Set your timing, then save the changes.
Turn Enable Auto-Lock off and the lock stops acting on its own — it waits for you. That toggle is the whole off-switch, which is handy if you host guests or want the door to stay open for a stretch.
On earlier locks, this feature is not part of the package. For a tested shortlist of options that cover the feature well, this roundup of automatic locking deadbolts compares the models worth a look.
What Auto-Lock Is Not
Auto-Lock and Auto-Unlock are separate features that people often mix up — and Auto-Unlock works on an entirely different principle.
Auto-Lock, by contrast, is purely about securing the door after it closes. One locks up after you; the other lets you in before you reach the door.
It is worth being clear on the limits, too. Auto-Lock only engages when the door is actually closed — a timer counts down, but a door standing open gives it nothing to lock. If the bolt meets resistance from a misaligned strike plate, the lock reports a problem rather than forcing through. Keeping the door aligned is what keeps automatic locking reliable over time.
The clearest way to think about any automatic locking deadbolt: it removes the one decision you can forget. You still carry a key. You still turn a thumbturn when you want to. But the closed door handles the rest — and August’s own explanation of Auto-Lock confirms the point: secure once closed, or secure after your chosen delay.
The short version: timer mode locks after a delay you set, instant mode locks the instant the door shuts, and both run through the app’s Auto-Lock toggle. Pick the mode that matches how you actually use the door — a timer if you want a grace period, instant if you want the door never left open-but-unlocked. Turn the toggle off when you need the lock to stand down.
FAQs
Does Auto-Lock still work if my phone is inside the house?
Yes. Once Auto-Lock is configured, the lock acts on its own trigger — the timer or the door closing — without needing your phone nearby. Your phone matters for setup and for Auto-Unlock, not for the locking behavior itself.
Can I use Auto-Lock without DoorSense?
You can use timer-based Auto-Lock without DoorSense. The instant, close-triggered behavior depends on DoorSense being installed and calibrated, so without it you are limited to a countdown delay before the bolt engages.
Will my regular key still work after installing one?
Yes. Because the smart lock attaches to the inside of an existing single-cylinder deadbolt, the outside lock and its keyway are untouched. Your original keys keep working alongside the automatic locking behavior.
References & Sources
- August. “Auto-Lock” Describes how Auto-Lock secures the door once closed or after a set delay.
- August. “How Do I Enable Auto-Lock?” Documents the in-app steps for enabling and adjusting Auto-Lock timing.
- August. “Intelligent Auto-Lock With DoorSense” Explains the DoorSense-based instant locking behavior and requirements.
