Seiko 5 & Fitbit Charge on the same wrist

Seiko 5 & Fitbit Charge on the same wrist

Yes. The Seiko 5 is compatible with Smartlet One, on watch adapters matching its 18mm / 20mm / 22mm lug width. The Fitbit Charge 5 and 6 adapters are in the box. The Seiko sits on top of the wrist; the Charge sits underneath, against the skin. Google does not certify readings taken in this position.
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Compatibility guide

Seiko 5 & Fitbit Charge on the same wrist

Seiko 5 + Fitbit Charge
Yes. The Seiko 5 is compatible with Smartlet One, on watch adapters matching its 18mm / 20mm / 22mm lug width. The Fitbit Charge 5 and 6 adapters are in the box. The Seiko sits on top of the wrist; the Charge sits underneath, against the skin. Google does not certify readings taken in this position.
Seiko 5 lug width
18mm / 20mm / 22mm
Fitbit Charge compatibility
Charge 5 / 6
Adapter
Fitbit Charge adapters in the box
Sensor position
Underneath the wrist

Why first-watch enthusiasts pair the Seiko 5 with Fitbit Charge

Is the Seiko 5 compatible with Fitbit Charge on Smartlet?

Compatible
Yes. The Seiko 5 is compatible with Smartlet One, on watch adapters matching its 18mm / 20mm / 22mm lug width. The Fitbit Charge 5 and 6 adapters are in the box. The Seiko sits on top of the wrist; the Charge sits underneath, against the skin. Google does not certify readings taken in this position.
Seiko 5 lug width
18mm / 20mm / 22mm Supported
Watch adapters in the lug holes
Fitbit Charge model
Charge 5 / 6
Fitbit Charge adapters in the box
Sensor position
Underneath the wrist
Not certified by Google in this position
Reversible
Fully
No modification to the watch

Related compatibility guides

Model guide
Seiko 5
→
Brand guide
All Seiko models
→
Smartwatch guide
Fitbit Charge compatibility
→

More ways to wear Smartlet

Seiko Prospex + Fitbit Charge
Seiko Prospex
→
Hamilton Khaki Field + Fitbit Charge
Hamilton Khaki Field
→

Choose your Smartlet

Step by step

Replace your strap
01

Replace your strap

The watch adapters seat in your mechanical watch's lug holes in place of the spring bars. Classic, Shadow or Titanium. The spring bar tool is in the box.

Connect your wearable
02

Connect your wearable

Your smartwatch attaches to the central part of the bracelet with its own adapter (Apple Watch, Whoop, Fitbit, Galaxy or Pixel Watch) or a pair of standard watch adapters. Zero modification to the mechanical watch.

Wear both simultaneously
03

Wear both simultaneously

Both watches sit on the same wrist. The smartwatch sits underneath, against the skin; readings taken there are not certified by its manufacturer.

Questions

Frequently asked questions

  • Which Seiko 5 references work with Smartlet?
    References with 19mm / 20mm / 22mm lug widths are covered, with watch adapters in the matching width. The Seiko 5 model guide lists every reference.
  • Is the Fitbit Charge adapter included?
    Yes. Every Smartlet One ships with the Fitbit Charge 5 and 6 adapters in the box.
  • Will Smartlet damage the Seiko 5?
    No. The watch adapters seat in the Seiko 5's lug holes in place of the spring bars, like a strap change. The watch is untouched and the change is fully reversible.
  • Does Smartlet damage or modify my mechanical watch?
    No. The watch adapters seat in your watch's lug holes in place of the spring bars. Nothing is modified on the case, lugs or dial, and the change is fully reversible: your mechanical watch can go back on its original strap at any time.