Quick Verdict
A widely sold classic that has outlived every watch designed to replace it. At 21 grams with a seven-year battery, the F-91W is less a purchase than a default.
At a Glance
- Typical street price
- $30
- Movement type
- Quartz
- Power reserve
- Battery, approximately 7 years on a CR2016 (Casio specification)
- Case width
- 35.2 mm
- Lug-to-lug
- 38.2 mm
- Crystal
- Resin glass
- Water resistance
- Water Resistant (Casio publishes no depth rating)
Design
The 38.2 x 35.2 mm resin case has not changed since 1989, and neither has the red and blue print around the display. It is not a design that was styled so much as one that was solved, which is why it still looks deliberate next to watches forty years younger.
Movement
A Casio digital quartz module rated at ±30 seconds a month and powered by a CR2016 that Casio specifies for roughly seven years. There is nothing to service and nothing to set beyond the date rollover the auto-calendar handles itself.
Build Quality
Resin case, resin glass, moulded strap. The glass is the compromise: it will pick up scratches that a mineral crystal would shrug off. Everything else is built to be forgotten about.
Dial
A grey LCD behind a black printed face carrying the CASIO and F-91W lettering, ALARM CHRONOGRAPH across the top and WATER RESIST at the bottom. Legibility in daylight is excellent; the LED light covers the display adequately rather than well.
Bracelet & Strap
The resin strap is moulded into the case, so there is no lug width and no strap swap. Casio specifies a fit range of 145 to 200 mm, which covers almost every adult wrist and a good number of children's.
Comfort & Wearability
21 grams and 8.5 mm thick. It disappears under a cuff and it disappears on the wrist, which is the whole argument for owning one.
Accuracy
Casio specifies ±30 seconds per month. That is roughly one second a day, and it needs no winding, no wearing and no attention to hold it.
What we like
What we like
- 21 g on the wrist and 8.5 mm thick — the closest a watch gets to wearing nothing
- Seven years on one CR2016, so it is genuinely maintenance-free
- ±30 seconds a month, an order of magnitude tighter than any mechanical watch here
- Alarm, hourly signal, 1/100 stopwatch with split timing and an auto-calendar
What we don't like
- Casio publishes no depth rating — only 'water resistant', which means splashes
- Resin glass scratches where mineral would not
- The LED light is dim by modern standards and lights one corner of the display
Who Should Buy It?
Anyone who wants a second watch that costs less than a strap, anyone who needs something they will not care about damaging, and anyone who values being on time over being looked at.
Who Should Skip It?
Skip it if you swim or dive. Casio publishes no depth rating for this reference, and the AE-1200WH at 100 m is the obvious step up inside the same catalogue.
Best Alternatives
Three watches worth weighing up before you commit.
How It Compares
Casio F-91W
1 categories won
Casio A158WA
2 categories won
- Typical street price
- $30Even
- $30Even
- Movement type
- Quartz
- Quartz
- Caliber
- Not published
- Not published
- Power reserve
- Battery, approximately 7 years on a CR2016 (Casio specification)
- Battery, approximately 7 years on a CR2016 (Casio specification)
- Stated accuracy
- ±30 seconds per month (Casio specification)
- ±30 seconds per month (Casio specification)
- Case width
- 35.2 mm
- 33.2 mm
- Case thickness
- 8.5 mm
- 8.2 mmWinner
- Lug-to-lug
- 38.2 mm
- 36.8 mmWinner
- Crystal
- Resin glass
- Resin glass
- Water resistance
- Water Resistant (Casio publishes no depth rating)
- Water Resistant (Casio publishes no depth rating)
- Bracelet / strap
- Resin strap
- Stainless steel bracelet
- Weight
- 21 gWinner
- 46 g
- Style
- Digital · Everyday
- Digital · Everyday · Dress
- Recommended wrist
- Small · Medium
- Small · Medium
- Selection Score
- Not published
- Not published
Final Verdict
The F-91W is the reference point for what a watch has to cost and what it has to weigh. Nothing else in this database gives away so little for so little.
Specifications
- Brand
- Casio
- Model
- F-91W
- Reference
- F-91W-1
- Collection
- Not published
- Typical street price
- $30
- MSRP
- $30
- Movement type
- Quartz
- Movement
- Casio digital quartz module
- Caliber
- Not published
- Power reserve
- Battery, approximately 7 years on a CR2016 (Casio specification)
- Stated accuracy
- ±30 seconds per month (Casio specification)
- Balance spring
- Not published
- Case width
- 35.2 mm
- Case thickness
- 8.5 mm
- Lug-to-lug
- 38.2 mm
- Lug width
- Not published
- Weight
- 21 g
- Case material
- Resin
- Crystal
- Resin glass
- Water resistance
- Water Resistant (Casio publishes no depth rating)
- Dial colours
- Black
- Bracelet / strap
- Resin strap
- Bracelet material
- Resin
- Clasp
- Not published
- Date
- Yes
- GMT
- No
- Chronograph
- Yes
- Style
- Digital · Everyday
- Recommended wrist
- Small · Medium
- Country of origin
- Japan
- Released
- 1989
- Selection Score
- Not published
Score Breakdown
Where to Buy
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Amazon
Price shown on Amazon
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Casio
Not published
Frequently Asked Questions
Can the Casio F-91W get wet?
Casio rates it as 'water resistant' without stating a depth, which in Casio's own scale means splashes and rain rather than swimming. If you want to swim in a cheap Casio digital, the AE-1200WH is rated to 100 m.
How long does the F-91W battery actually last?
Casio specifies approximately seven years from one CR2016. Heavy use of the LED light shortens that, but it is still measured in years rather than months.
