Casio’s Viral-Hit Sauna Watch Is Now Available Stateside for the First Time

Back in 2024, Casio announced a surprising, if not random, new wristwatch that was unlike anything we’d seen before. Beyond just durable, this was a timepiece explicitly made for sitting in a sauna, resistant to extreme heat and humidity. However, fans in the U.S. had to gaze longingly at these Japan-exclusives (or spend at least double the suggested retail on the secondary market). Now they’re available Stateside for the first time.

A PASSION PROJECT GONE RIGHT

The SADOKEI (sauna watch, essentially) began development around 2021, when a small group of sauna-obsessed Casio engineers spotted a real gap: nothing on the market could survive the repeated 100°C punishment of a proper Japanese sauna session without either burning your wrist or failing internally. Three years of prototyping later, they landed on a watch built from scratch for that exact purpose, and launched it on Japanese crowdfunding platform Makuake in late 2024. It sold out in one day, with over 2,000 backers. Restocks in Japan have been selling out ever since, often distributed by online lottery.

The SAN100H is also the first product released in the U.S. under Casio Lab, the company’s experimental direct-to-consumer initiative launched in 2025 for employee-driven projects too niche for the main catalog. Think of it as Casio’s skunkworks, where the ideas that don’t fit neatly under G-SHOCK or Baby-G get a shot anyway.

PURPOSE-BUILT, TOP TO BOTTOM

As for the watch itself, the 35.4mm resin case is constructed from low-moisture-permeability material that keeps the internal components protected. It’s equipped only with a single metal screw that’s recessed so it never contacts your skin. The battery, a BR1225A, is rated to 212°F (water’s boiling point) and has a projected five-year lifespan. Mineral glass keeps the dial readable, and hands get LumiBrite lume for low-light visibility. Weighing under an ounce, you’ll honestly forget you’re wearing it.

The coil-spring strap is easily the most intriguing part of this watch, and something we’d like to see more of. Inspired by the locker key straps ubiquitous in Japanese saunas and gyms, it stretches over the hand and sits securely on the wrist without any metal hardware to heat up. It’s a a functional and ingenious solution, and it gives the SAN100H a look unlike anything else in your collection.

Keep It Minimal

Functionally, the SAN100H keeps things minimal. A single button toggles between Standard Time Mode and Sauna Mode, the latter running a 12-minute countdown that mirrors the timer dial you’d find posted on a sauna room wall. That 12 minutes aligns with Japanese sauna tradition, where sessions are structured in sets of sauna, cold bath, and rest. Two bullhead-style pushers at the top toggle between the settings. There’s no Bluetooth, no step counter, and no altimeter, keeping things as low-tech as possible.

Another thing is that water resistance caps at 50m, which is notably less than almost every G-SHOCK model ever (though some standard Casios have been just splash-resistant). For actual sauna use, none of that matters. But if you’re planning to take this lap swimming after your session, just know its limits.

SPEC SHEET

PRICING & AVAILABILITY

The Casio SAN100H is available now through Casio Lab’s page for $110 in two colorways: full black (SAN100H-1B) and black with white and orange accents (SAN100H-7B). Shipping is limited to the U.S. These have already sold out in its initial run, but we can expect a restock soon.

Recap

Casio SAN100H SADOKEI Sauna Watch

Casio’s long-awaited SADOKEI sauna watch has officially landed in the U.S. for $110 through Casio Lab, available in two colorways. It’s a purpose-built tool watch with a heat-resistant resin case, coil-spring strap, and a 12-minute sauna timer.

Learn More: Casio