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The quick verdict
The bottom line: The Casio F-91W remains the best watch you can buy for around $20. It is light, tough, endlessly reliable, and the battery lasts years. Nothing else at this price comes close.
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Introduction
The Casio F-91W launched in 1989 and barely changed since. That is not laziness, it is proof the design was right the first time. I have owned and worn F-91Ws for years, and this review is based on long-term, real-world use, not a weekend unboxing.
Watch: the full video review
Price and where to buy
The F-91W typically sells for $15 to $25. At that price there is no real competition. One warning: fakes are extremely common, so buy from a reputable seller. I put together a guide on how to spot a fake F-91W if you want to check the one you have.
Design and build
The F-91W is small, light (about 21 grams), and made of black resin. It wears comfortably on almost any wrist and disappears under a shirt cuff. The resin case and strap will not win beauty contests, but they survive daily abuse that would scratch up a metal watch. The pushers have a firm, positive click that still feels right decades into the design’s life.
Display and readability
The LCD display is simple and legible: time, date, day of the week, and a small seconds readout. Contrast is good in daylight. The backlight is famously dim, a greenish glow that barely helps in the dark. It is the watch’s worst feature and somehow part of its charm.
Features
For $20 you get more than expected:
- Daily alarm and hourly time signal
- 1/100-second stopwatch
- Auto calendar (no need to set month lengths)
- Water resist rating for splashes and rain (do not swim with it)
Everything is operated through three pushers with a logical, learnable layout. The manual is one page and you will memorize it in a day.
Battery life
Casio rates the CR2016 battery at 7 years. In practice, most owners get 5 to 7 years of normal use. When it finally dies, any watch shop can swap the cell for a few dollars and the watch keeps going.
What I do not like
- The backlight is nearly useless in the dark.
- The resin strap collects dust and can irritate sensitive skin over long days.
- It is only splash resistant, not a swim watch.
- The alarm beep is quiet. Heavy sleepers, look elsewhere.
Specs
| Spec | Detail |
|---|---|
| Module | Casio 593 |
| Case size | 37.5 x 33.5 x 8.5 mm |
| Weight | 21 g |
| Case and strap | Black resin |
| Battery | CR2016, approx. 7 years |
| Water resistance | Water Resist (splashes only) |
| Functions | Alarm, hourly signal, stopwatch, auto calendar |
Pros and cons
Pros:
- Unbeatable value around $20
- Extremely light and comfortable
- 5 to 7 year battery life
- Tough resin build that shrugs off daily wear
- Timeless, recognizable design
Cons:
- Dim backlight
- Splash resistant only
- Resin strap is basic
- Fakes are everywhere, buy carefully
FAQ
Is the Casio F-91W worth it in 2026?
Yes. Nothing has replaced it at this price. It remains the default recommendation for a cheap, reliable digital watch.
Is the F-91W water resistant enough for swimming?
No. It is rated Water Resist, which covers splashes and rain. Do not swim or shower with it.
How long does the battery last?
Casio claims 7 years, and 5 to 7 years is realistic with normal use.
How can I tell if my F-91W is fake?
Check the dial printing, the engraved case back, and the backlight color. My fake-spotting guide walks through all three checks.
Final verdict
The Casio F-91W is the rare product that has nothing to prove. It costs less than a pizza, lasts the better part of a decade, and tells the time without fuss. If you want an honest, no-nonsense watch, buy it and do not overthink it.