Casio F-91W Digital Watch (Black)

The classic black resin Casio digital watch: very light, simple, with a battery Casio rates at about seven years — a style piece, not a sports or swim watch.

Quick verdict

Yes, if you want a cheap, featherweight everyday watch with a classic look. The Casio F-91W covers time, date, an alarm, a stopwatch and a small light, on a battery Casio rates at about seven years. It isn't a swim watch and its light is weak, so choose a water-rated sports watch if you need either.

Best for:: A light, classic everyday watch with a long-life battery.
Watch out:: Not a swim watch; the light is weak.

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Amazon US listing and availability checked October 26, 2026. Prices and stock can change.

Reviewed October 7, 2026 · How we review

Part of our buying guide: Choosing a Simple Digital Watch: Readability, Fit, Features and Water Resistance

Casio F-91W digital watch in black resin, with the blue-trimmed face and "Water Resist" marking

Photo credits

Our Take

The F-91W has been in production since 1989 and has had a strong revival: US search interest has roughly quadrupled since 2021, peaking in early 2026. The appeal is simple. It's an inexpensive, featherweight resin watch with a clean retro look that works with almost anything, and it does the basics — time, day and date, a daily alarm, a 1/100-second stopwatch and a small light — on a CR2016 coin cell Casio rates at about seven years. Its limits are just as clear: the case is marked "Water Resist" with no depth rating, so treat it as rain-and-handwash safe rather than a swim watch, the light is a small side lamp that's weak by modern standards, and the resin strap is the part most likely to wear out. Because it's widely copied, buy it from a listing sold by Amazon.com or Casio.

Specs (This Configuration)

Model: F-91W-1 (black resin case and strap)
Display: Time with seconds, day and date
Functions: Daily alarm, 1/100-second stopwatch, light
Battery: CR2016, about 7 years (Casio)
Water resistance: Marked "Water Resist" — no depth rating

Best For

Anyone who wants a light, low-stakes everyday watch with a classic retro look
People who want to wear a watch instead of checking their phone for the time
A simple first watch for a teenager

Skip If

You need a watch for swimming or diving
You want a bright backlight for reading it in the dark
You want step counting, notifications or other smartwatch features

What We Like

Very light resin case and strap that's easy to forget you're wearing
A battery rated at about seven years, with no charging
A design that's barely changed in decades, so it doesn't date

What To Know

The case says "Water Resist" without a depth rating, so keep it out of the pool and shower
Counterfeits are common; buy from a listing sold by Amazon.com or Casio and check the seller at checkout
Amazon groups several F-91W colors in one listing — make sure the black F-91W-1 is selected
The resin strap can crack after a few years; replacement straps are available

Pros

Featherweight and comfortable
Long battery life with no charging
Classic look that suits most outfits

Cons

Not suitable for swimming
Weak light by modern standards
Resin strap wears over time

Alternatives

Casio F-105W-1A — A similar-looking Casio with an electroluminescent backlight — choose it if being able to read the watch in the dark matters more than the F-91W's exact look.View on Amazon
A water-rated digital sports watch — If you swim or work in wet conditions, a watch rated to a stated depth (for example 100 m or more) is the safer choice.

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Why PriceDropIQ Selected It

If you want a watch you never have to think about, this is the obvious one: it's very light, cheap to replace, easy to read and runs for years on one battery. It suits you only if you accept what it isn't, meaning not a swim watch and not a smartwatch.