Can you make an analog watch smart?
Founder & CEO, Smartlet - CentraleSupelec engineer - Concours Lepine 2025, Awarded - CES 2026
Contents
Not from the inside: a mechanical movement runs on a mainspring and has no power for sensors or Bluetooth. What you can do is add the smart part next to your watch, on the caseback, in the strap, on the other wrist, or under the same wrist. Each way keeps a different share of the watch you love. Here is what each one gives you, and what it costs.
- The movement stays analog. A mechanical watch stores its energy in a mainspring; there is no battery to run electronics.
- Hybrid watches replace your watch. They are smart from the start, with hands on the dial and sensors inside.
- Caseback trackers are new. Ganance Heir, announced in 2026, holds on the caseback by suction and counts steps, without heart rate.
- Smart straps have mostly gone. Sony stopped Wena 3 production in February 2023 and ended its services on 28 February 2026.
- The smartwatch can sit under the same wrist. The Smartlet holds your mechanical watch on top and the smartwatch underneath, on one metal link bracelet.
Why the watch itself cannot become smart
A mechanical watch is powered by the wearer: winding, by hand or by the rotor, tensions a long thin spring, the mainspring, which releases that energy to the gear train (Time+Tide). There is no battery and no circuit. To count steps, read a heart rate or buzz for a message, something electronic has to be added from outside the case.
So the real question is where that electronic part goes, and how much of your watch it changes. There are five answers.
Five ways to add the smart part
| Way | Your mechanical watch | What you get | The catch |
|---|---|---|---|
| Hybrid watch | Replaced | Hands on a dial, sensors inside | It is a different watch |
| Tracker on the caseback | Kept | Steps, notifications | Limited sensors, between the case and the skin |
| Smart strap or buckle | Kept, on a new strap | Steps, notifications, payment | Few products left on sale |
| Smartwatch on the other wrist | Kept | Everything a smartwatch does | Two wrists, two watches visible |
| Smartwatch under the same wrist | Kept, on top | Everything a smartwatch does | One bracelet for both, not made for sport |
The first way replaces the watch; the other four keep it. The difference between them is how much of the smartwatch you get, and where it sits.
1. A hybrid watch: smart from the start
Hybrid watches put analog hands over a case full of sensors. Withings ScanWatch 2 lists up to 35 days of battery, an ECG, 24/7 heart rate, SpO2 and sleep tracking, at $369.95 on its US site (Withings). Casio's Bluetooth models take another route: they connect to a phone to keep the time accurate and add world time and a phone finder (Casio).
The category also shrinks: Fossil announced in January 2024 that it was leaving the smartwatch business (GSMArena). A hybrid answers the question by replacing your mechanical watch, which is exactly what most people asking it want to avoid.
2. A tracker on the caseback
The newest idea is a small sensor held on the back of the watch. Ganance Heir, announced in 2026, is a 30 mm disc of 5 g that holds on the caseback by suction, tracks steps, distance and active time, and vibrates for calls and messages; according to press reports it has no heart rate sensor and was priced at $149 (Notebookcheck).
It keeps your watch on its own strap. The trade-off is in the sensor: a disc this size, sitting between the case and the skin, measures less than a smartwatch does.
3. A smart strap or buckle
For a few years, the strap was the answer: electronics in the buckle, the watch on top. The best-known example, Sony's Wena 3, is gone. Sony told ITmedia that production ended in February 2023 (ITmedia), and all Wena 3 services, from the app to payments, ended on 28 February 2026 (Sony).
We found no smart strap we could confirm is still on sale in 2026. More on what Wena owners can do now in the Sony Wena article.
4. A smartwatch on the other wrist
The oldest way needs nothing new: the watch on one wrist, the smartwatch on the other. Many people already own both: in a 2017 survey of US broadband households, 82% of smartwatch users also owned a traditional watch (Parks Associates). Owning both is not wearing both, and two watches in plain view is a statement not everyone wants to make. The history of the habit is in wearing two watches.
5. A smartwatch under the same wrist
The Smartlet is a metal link bracelet that replaces the straps of both watches: your mechanical watch on top of the wrist, your smartwatch or tracker underneath, in the central part of the bracelet, against the skin. The watch adapters seat in your watch's lug holes in place of the spring bars, so the watch is not modified, and it goes back on its own strap whenever you want.
It takes mechanical watches with standard spring bars in 18 to 24 mm lug width; 23 mm is coming soon. Both Apple Watch adapter sizes and a Whoop 5.0 and MG adapter are in the box; the Galaxy Watch 8 and later and Pixel Watch adapters come when you select them at order. Check your watch in the lug width finder.
Apple writes that its sensors "will work only if you wear your Apple Watch on the top of your wrist" (Apple). Screenless trackers such as Whoop 5.0 and MG (Android Authority), Fitbit Air (9to5Google) or Polar Loop (Polar) have no screen to read, which suits a place under the wrist. For a reading with medical weight, put the device back on its own band.
How to choose
- You want one object and no compromise on health data: a hybrid watch, knowing it replaces your mechanical watch.
- You want to keep your watch and only count steps: a caseback tracker.
- You want your watch and a full smartwatch, and two wrists suit you: wear one on each.
- You want your watch and a full smartwatch on one wrist: the smartwatch underneath, on a Smartlet.
- For sport, whatever you choose: no metal bracelet is made for sport, so the smartwatch goes back on its sport band.
Smartlet, Bronze Medal at Concours Lepine 2025 and shown at CES 2026, is the fifth way. See smartwatch compatibility and watch brand compatibility.
