Casio's F-B100W adds Bluetooth and step tracking to a £55 digital watch with two-year battery life

Casio's F-B100W is a conventional digital watch with a step counter and limited Bluetooth connectivity, not a smartwatch. There is no touchscreen, app store, or stream of notifications. It pairs with Casio's smartphone app to record activity, adjust settings, and keep its clock accurate, and it costs £55.

The battery strategy is the key engineering trade-off. The watch sends only one Bluetooth Low Energy update to the phone at the end of each day, which is how it achieves approximately two years of operation from a single replaceable CR2016 lithium button cell. That battery costs roughly a dollar, and the design avoids the daily or weekly charging cycle typical of smartwatches.

This is not a radical innovation for Casio. The existing ABL-100 already does much the same thing, but costs over 25 percent more and weighs more than twice as much. The F-B100W brings the same functionality to a smaller, cheaper, and lighter package, which is the actual change worth noting.

Syncing officially requires Casio's proprietary smartphone app, but FOSS alternatives such as Casio G-Shock Smart S already exist. In Casio's pricier G-Shock range, models like the GBD-200 and GBD-300 offer bidirectional Bluetooth with on-screen notifications and silent vibrating alerts, which the F-B100W does not. The lower-end models are deliberately limited to one-way daily sync to preserve battery life.

Community discussion on Hacker News and Reddit raised practical concerns, including that many low-end Casios can only display dates in US MM/DD format, with European-format dates requiring more expensive models. This suggests that despite the connected features, some basic software limitations remain tied to the product tier rather than being fixable via the Bluetooth link.