August Smart Lock 3rd Gen vs 4th Gen: Should You Upgrade?

If you own an August Smart Lock Pro 3rd Generation and you have been wondering whether to upgrade to the newer 4th Gen August Wi-Fi Smart Lock, you are asking the right question. The differences are now well understood, the trade-offs are clear, and we have installed both versions in enough NYC apartments to tell you exactly when the upgrade makes sense and when it does not.

Short answer: for most NYC apartment owners with a working 3rd Gen lock, the 4th Gen is worthwhile only if you have not yet bought an August Connect bridge, or if your bridge is causing connectivity headaches. If your 3rd Gen setup works reliably and you already own the bridge, the upgrade is a nice-to-have rather than a need-to-have.

At a Glance: Side-by-Side Comparison

Quick comparison of the two generations, with the winner of each category highlighted.

The Core Trade-Off: Size & Wi-Fi vs Battery Life

When August designed the 4th Generation, they had to make a hard engineering choice. They wanted to build Wi-Fi directly into the lock — so customers no longer need the separate Connect bridge — and make the lock significantly smaller so it would not dominate the interior of your door.

To do both, they reduced the size by 45 percent and made the lock 20 percent thinner. The trade-off was battery space. The 3rd Generation uses four AA batteries. The 4th Generation uses two CR123 batteries, which are physically smaller. Combined with the always-on Wi-Fi radio drawing more power than Bluetooth alone, the result is that the 4th Generation battery life is roughly half of the 3rd Generation.

This is the central trade-off between the two locks. Everything else flows from that single engineering decision.

Connectivity: The Single Biggest Difference

3rd Gen: Bluetooth + Bridge Required

The 3rd Generation has Bluetooth and Z-Wave Plus built in, but no Wi-Fi. To use the lock remotely through the August app, Apple HomeKit, Alexa, or Google Assistant, you need to plug in a separate August Connect bridge. The bridge costs $80 separately, needs a wall outlet within 30 feet of the lock, and is a single point of failure for all remote features.

In NYC apartments, this creates real challenges. Railroad-style layouts may force awkward bridge placement. Thick plaster walls degrade both Wi-Fi and Bluetooth signal. If the bridge ever fails, you lose all remote access until it is replaced.

4th Gen: Built-In Wi-Fi, No Bridge

The 4th Generation eliminates the bridge dependency by building Wi-Fi directly into the lock. Connect it to your home Wi-Fi during setup and you are done — no external hardware to position, no outlet to find, no bridge to fail. This is the headline feature that justifies most upgrades from 3rd Gen to 4th Gen.

The 4th Gen retains Bluetooth for local app control and auto-unlock. What it loses is Z-Wave Plus. For most NYC homeowners this does not matter, but for Airbnb hosts and property managers using Z-Wave-based systems, this is a reason to prefer the 3rd Gen.

Battery Life: 3rd Gen Wins Comfortably

Over a five-year period, the 3rd Gen needs 5 to 8 battery changes. The 4th Gen needs 10 to 18 with disposables. If minimizing maintenance is important to you, the 3rd Gen wins by a clear margin.

Features and App Experience

Both generations use the same August app with the same core feature set: DoorSense, auto-unlock by phone proximity, auto-lock timer, guest access codes with scheduling, activity logs, geofencing, and integration with Apple HomeKit, Alexa, and Google Home.

Where the 4th Gen Pulls Ahead

Faster auto-unlock recognition thanks to a newer Bluetooth chip. Remote app commands execute about half a second faster than the 3rd Gen with bridge. Supports more concurrent user codes and longer activity history retention. Native HomeKit is meaningfully more reliable than bridge-mediated HomeKit — automations execute faster and connection drops are rarer.

Where the 3rd Gen Holds Its Own

Slightly more customizable notification settings. Some power users prefer the 3rd Gen's granular control over which events trigger notifications. The 4th Gen simplified these settings, which is friendlier for casual users but less flexible for advanced setups.

Installation in NYC Apartments

Both generations install entirely on the interior side of your existing deadbolt. The exterior of your door remains untouched, and your landlord's key still works. This is the reason August remains our top recommendation for NYC renters.

• 3rd Gen install takes 10–15 minutes plus another 10 minutes to set up the Connect bridge. A Phillips-head screwdriver is the only tool needed. Multiple deadbolt adapters are included in the box.
• 4th Gen install takes 8–12 minutes total. No bridge to configure. CR123 batteries come pre-installed. The smaller housing is easier to maneuver in tight spaces.
• Both installs are DIY-friendly for a confident homeowner. If your deadbolt is misaligned, sticky, or non-standard, professional installation is the wiser choice.
• Rainbow Locksmith NY installs both generations throughout all five boroughs starting at $125. Free phone consultations to help you decide which to buy.

Security Considerations

Both locks have the same fundamental security profile — they both retrofit onto your existing deadbolt without changing exterior hardware. The lock cylinder, the deadbolt itself, and the strike plate are all unchanged. Someone trying to force your door faces the same physical defenses with or without an August installed.

Both generations use 128-bit AES encryption for Bluetooth communications and have undergone independent security audits. Both receive timely firmware updates from August. If anything, the 3rd Gen has a slight edge in security track record because it has been in the wild longer and any vulnerabilities have been discovered and patched over nearly a decade of real-world use.

Pros & Cons: Head to Head

When to Upgrade — and When to Skip

Upgrade to the 4th Gen if:

• You do not own a Connect bridge yet. Buying the bridge or upgrading to a 4th Gen costs roughly the same. The 4th Gen is the cleaner long-term choice.
• Your bridge is failing or unreliable. Replacing a bridge costs $80. Sell your used 3rd Gen for $50–$80 and the upgrade economics get close to even, with a sleeker lock to show for it.
• You want native Apple HomeKit. The 4th Gen's HomeKit is meaningfully more reliable than bridge-mediated HomeKit — faster automations, fewer connection drops.
• You are buying your first August lock in 2026. Start with the 4th Gen. It is the current-generation product with integrated Wi-Fi and a smaller footprint.

Stick with the 3rd Gen if:

• Your 3rd Gen works reliably. There is no functional reason to upgrade. The 4th Gen does the same things, just slightly faster and without the bridge.
• You value the longer battery life. The 3rd Gen genuinely lasts twice as long and uses batteries you can buy anywhere at 2am.
• You use Z-Wave property management. The 4th Gen drops Z-Wave entirely. Airbnb hosts and property managers with Z-Wave PMS integrations should stay on the 3rd Gen.
• Your front-door Wi-Fi signal is weak. In older NYC pre-war buildings with plaster walls, a 3rd Gen with a bridge positioned centrally often beats the 4th Gen's built-in Wi-Fi.

Which Generation Wins by Use Case

Frequently Asked Questions