Wear your Fitbit Charge and your mechanical watch at the same time

Wear your Fitbit Charge and your mechanical watch at the same time

Smartlet is compatible with the Fitbit Charge Charge 5 / 6 via the dedicated adapter included in every box. All health sensors remain fully operational with full skin contact maintained at all times. The setup takes under two minutes and is fully reversible.
Explore
Forbes · CNET
|
300+ clients
|
35+ countries
|
CES 2026 · Lépine 2025
|
Patented
Fitbit Charge compatibility

Wear your Fitbit Charge and your mechanical watch at the same time

In short Smartlet is compatible with the Fitbit Charge Charge 5 / 6 via the dedicated adapter included in every box. All health sensors remain fully operational with full skin contact maintained at all times. The setup takes under two minutes and is fully reversible.

Fitbit Charge 5 and 6 pack exceptional health density into a slim tracker: ECG, EDA stress sensor, SpO2, continuous heart rate. Smartlet positions your Fitbit Charge on the same wrist as your mechanical watch via the dedicated adapter included in every box.

Wear yours How it works
The problem
Choosing between health data and horological heritage every morning.
The solution
Smartlet replaces your mechanical watch strap and positions your Fitbit Charge on the same wrist via the dedicated adapter included in every box. Wear both simultaneously, without compromise to your watch or your health tracking.
Models
Charge 5 / 6
Lug width
Adapter included
Sensors
ECG +
Reversible
In seconds
Gallery

Fitbit Charge with Smartlet

Smartlet One - Classic - Smartlet
Classic - Smartwatch / Fitness trackers adapters set - Smartlet
Smartlet One - Shadow - Smartlet
Shadow - Smartwatch / Fitness trackers adapters set - Smartlet
Smartlet One - Titanium - Smartlet
Titanium - Smartwatch / Fitness trackers adapters set - Smartlet

Choose your edition

One mechanism. Three personalities.

Every Smartlet One includes the dedicated adapter for your wearable. Pick the finish that matches your style.

Smartlet One - Shadow - Smartlet

For the explorer

Smartlet One - Shadow

€399,00

4.9 (16)

Stealth. Switch in seconds, leave no trace.

  • Material SS316L steel, black PVD
  • Weight ~100g
  • Compatible with Rolex, Omega, Seiko + 100 more
Buy now
Compatibility

Fitbit Charge models supported

Fitbit Charge Charge 5 / 6
Compatible
Smartlet is compatible with the Fitbit Charge 5 and Charge 6 via the dedicated adapter included in every Smartlet box. ECG, EDA stress sensor, SpO2 and continuous heart rate remain fully operational with full skin contact maintained at all times.
All Fitbit Charge sensors remain fully operational

Smartlet positions your wearable with full skin contact maintained at all times. Health data accuracy is unaffected.

ECGEDA stress sensorSpO2Heart rateSleep trackingSkin temperature
Frequently paired

Mechanical watches worn with Fitbit Charge

The most common combinations our customers wear. Find your mechanical watch and discover the right Smartlet edition.

Rolex
Rolex Cosmograph Daytona·Rolex Datejust 41·Rolex Explorer·Rolex GMT-Master II
18.0mm / 19.0mm / 20.0mm / 21.0mm / 22.0mm / 23.0mm
Omega
Omega Aqua Terra·Omega Constellation Co-Axial·Omega De Ville Tresor·Omega Seamaster 300M
18.0mm / 19.0mm / 20.0mm / 21.0mm / 22.0mm / 23.0mm
Tudor
Tudor Black Bay 41·Tudor Pelagos 42·Tudor Ranger·Tudor Monarch
18.0mm / 19.0mm / 20.0mm / 22.0mm
TAG Heuer
TAG Heuer Aquaracer Professional 300·TAG Heuer Carrera Chronograph 42·TAG Heuer Formula 1·TAG Heuer Monaco
18.0mm / 19.0mm / 20.0mm / 21.0mm / 22.0mm
Seiko
Seiko Presage·Seiko Prospex SPB143·Seiko SKX Diver·Seiko Seiko 5
18.0mm / 19.0mm / 20.0mm / 21.0mm / 22.0mm / 23.0mm / 24.0mm
Breitling
Breitling Avenger·Breitling Navitimer B01 43·Breitling Superocean Automatic
20.0mm / 21.0mm / 22.0mm / 24.0mm
IWC
IWC Big Pilot·IWC Portugieser Automatic 40
18.0mm / 20.0mm / 21.0mm / 22.0mm
View all brands
27 brands covered
Combination guides

Wear it both ways

Hamilton Khaki Field + Fitbit Charge
Hamilton Khaki Field
→
Seiko Seiko 5 + Fitbit Charge
Seiko Seiko 5
→
Seiko Prospex SPB143 + Fitbit Charge
Seiko Prospex SPB143
→
Tudor Black Bay 41 + Fitbit Charge
Tudor Black Bay 41
→
Also compatible

Other smartwatches

Smartlet works with all major smartwatches via dedicated adapters or native lug widths.

Apple Watch
Samsung Galaxy Watch
Garmin Forerunner
Polar Vantage
Google Pixel Watch
Huawei Watch GT
Fitbit Air
Whoop
Garmin Venu
Withings Scanwatch
Coros
Suunto
Panther Eclipse
View all
Smartwatch compatibility guide

Step by step

Replace your strap
01

Replace your strap

Smartlet replaces your mechanical watch strap via the standard spring-bar system. Classic, Shadow, or Titanium. No tools required.

Connect your wearable
02

Connect your wearable

Smartlet uses a dedicated adapter or native lug pins depending on your smartwatch. The connector snaps onto the Smartlet module. Zero modification to the mechanical watch.

Wear both simultaneously
03

Wear both simultaneously

Both watches sit on the same wrist. All smartwatch sensors maintain direct skin contact and operate normally.

Questions

Frequently asked questions

  • Can I wear a Fitbit Charge and a mechanical watch at the same time?
    Yes. Smartlet makes it possible to wear your Fitbit Charge and a mechanical watch simultaneously on the same wrist. Smartlet replaces your mechanical watch strap via the standard spring-bar system and holds your Fitbit Charge against the same wrist. Both watches run at the same time. All Fitbit Charge health sensors maintain full skin contact and operate normally. You no longer have to choose between health data and your mechanical watch every morning.
  • Which Fitbit Charge models are compatible with Smartlet?
    Smartlet is compatible with the Fitbit Charge Charge 5 / 6. The Fitbit Charge uses a proprietary connector. A dedicated adapter, included in every Smartlet box, bridges it to the Smartlet module. Setup takes under two minutes and requires no tools. Smartlet is compatible with any mechanical watch between 18mm and 24mm lug width, covering the vast majority of the market including Rolex, Omega, Tudor, TAG Heuer, Seiko, Breitling, and IWC.
  • Will Fitbit Charge sensors still work when used with Smartlet?
    Yes, all sensors remain fully operational. Smartlet positions the Fitbit Charge against your wrist with full skin contact maintained at all times. The following sensors continue to function normally: ECG, EDA stress sensor, spo2, heart rate, sleep tracking, skin temperature. There is no interference with the sensor array, and health data accuracy is unaffected.
  • Does Smartlet damage or modify my mechanical watch?
    No. Smartlet replaces your standard watch strap using the existing spring-bar system. It makes no permanent modification to the watch case, lugs, or dial. The process is fully reversible in seconds. Your mechanical watch is unaffected and can be worn independently at any time by reinstalling its original strap. Smartlet is engineered to watchmaker tolerances and tested with the same care that goes into the watches it pairs with.