# Casio F-91W
The **Casio F-91W** is a resin-cased quartz digital wristwatch introduced by Casio in 1989 and still in continuous production with its original design, selling around 3 million units a year at prices that have stayed in the low tens of dollars[2](https://note-pr.casio.co.jp/n/ndd63897e6745?hl=en) • [3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/). Casio describes it, alongside the metal-cased A-158W, as one of its iconic long-selling models, sold worldwide since 1989 with almost no changes to the basic design[2](https://note-pr.casio.co.jp/n/ndd63897e6745?hl=en).
| Key fact | Detail |
|---|---|
| Launched | June 1989, confirmed in writing by Casio America and by Casio's own records[4](https://madesince.com/object/casio-f-91w/) |
| Case | 38.2 × 35.2 × 8.5 mm, 21 g, resin case and bezel, resin band[5](https://www.casio.com/jp/watches/casio/product.F-91W-1/) |
| Movement | Casio quartz Module 593, rated ±30 seconds per month[1](https://www.shopcasio.shriro.com.au/products/f91w-1) |
| Battery | One CR2016 lithium cell, rated about 7 years (assuming 20 seconds of alarm and 1 second of light per day)[6](https://www.manualslib.tech/en-gb/guide/241968/casio-f91w-manual.html) |
| Water resistance | Casio's Japanese page lists only daily-use water resistance; secondary sources cite 30 m / 3 ATM, which reviewers describe as a splash rating[5](https://www.casio.com/jp/watches/casio/product.F-91W-1/) • [7](https://www.gearpatrol.com/watches/casio-f-91w-review/) |
| Production | About 3 million units per year; cumulative totals above 100 million appear only in secondary reports, as Casio publishes no sales figures[3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/) • [8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html) • [9](https://www.bbc.com/news/magazine-13194733) |
| Price | Roughly $16–23 in the United States, £10.99 at Argos in the UK, a little over $20 per one report[10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w) • [3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/) • [8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html) |
## Design and specifications
The watch measures 38.2 × 35.2 × 8.5 mm and weighs 21 g, with a resin case, bezel, and band and daily-use water resistance[5](https://www.casio.com/jp/watches/casio/product.F-91W-1/). Inside is Casio's quartz Module 593, rated at ±30 seconds per month at normal temperature[1](https://www.shopcasio.shriro.com.au/products/f91w-1) • [6](https://www.manualslib.tech/en-gb/guide/241968/casio-f91w-manual.html). Functions are a 1/100th-second stopwatch with a measuring capacity of 59 minutes 59.99 seconds in elapsed, split, and 1st-2nd place modes, a daily alarm, an hourly signal, an auto-calendar set through February 28, and an LED light[1](https://www.shopcasio.shriro.com.au/products/f91w-1) • [6](https://www.manualslib.tech/en-gb/guide/241968/casio-f91w-manual.html) • [9](https://www.bbc.com/news/magazine-13194733) • [11](https://www.watchfinder.co.uk/articles/review-casio-f-91w). The calendar does not handle leap years, so February must be corrected manually[11](https://www.watchfinder.co.uk/articles/review-casio-f-91w). The lens is shatter-resistant acrylic, and the side-mounted backlight is widely criticized as very dim[3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/) • [11](https://www.watchfinder.co.uk/articles/review-casio-f-91w).
**Cost engineering.** Urethane resin is used for the case and band, the module has a reduced component count, and the band attaches with pins rather than standard spring bars to cut costs[1](https://www.shopcasio.shriro.com.au/products/f91w-1). These choices are what keep the retail price in the $16–23 range in the United States, with sale prices as low as $16[10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w).
**Water resistance.** Casio's Japanese product page states only "daily use" water resistance with no depth figure[5](https://www.casio.com/jp/watches/casio/product.F-91W-1/). Secondary sources commonly cite 30 m (3 ATM), and the case carries a "Water Resist" marking, but reviewers note this equals a splash rating not intended for swimming or showering[7](https://www.gearpatrol.com/watches/casio-f-91w-review/) • [12](https://thetestedhub.com/reviews/casio-f-91w/).
## History and development
The launch date is firmly documented. A 2020 investigation by News 3 Las Vegas obtained the date 06/1989 in writing from Casio America's customer service, the watch appears in Argos catalogs from 1990, and the BBC corrected its own dating to 1989 in January 2022[4](https://madesince.com/object/casio-f-91w/). One technology article states a 1991 release, but the maker's confirmation and the BBC correction support 1989[13](https://thenextweb.com/news/how-the-casio-f-91w-became-the-worlds-most-versatile-and-dangerous-watch).
The F-91W descended from the resin-cased, non-water-resistant F-5, with roughly 30 intermediate models made during the nine years of development before its release[11](https://www.watchfinder.co.uk/articles/review-casio-f-91w). It was the first watch designed by Casio's chief designer Ryusuke Moriai[11](https://www.watchfinder.co.uk/articles/review-casio-f-91w). Casio designer Kojima, interviewed by the company, describes being trained directly by the F-91W's designer to "be particular about 0.1mm", with design communication in 0.05 mm increments[2](https://note-pr.casio.co.jp/n/ndd63897e6745?hl=en).
Around the watch's 35th anniversary, Casio stated that manufacturing methods, production efficiencies, testing procedures, and quality-control systems have evolved over time, allowing continued reliable production without changing the design or user experience[14](https://www.t3.com/luxury/watches/casio-f91w-design-icon-0826).
## By the numbers
**Production.** The F-91W sells around 3 million units a year, which Esquire calls the most sold watch in history[3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/); other sources repeat the same annual figure[10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w) • [7](https://www.gearpatrol.com/watches/casio-f-91w-review/). Cumulative totals are less firm: one report states sales "well past 100 million units"[8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html), and a repairability reference estimates roughly 100 million produced by 2026 at about 3 million a year since June 1989[15](https://a1make.com/watches/casio-f91w/). The BBC, by contrast, reports that Casio does not release sales figures for the watch and says only that it was and is a "huge seller" worldwide, from Russia to Asia[9](https://www.bbc.com/news/magazine-13194733).
**Accuracy.** The rated figure is ±30 seconds per month, about six minutes per year[1](https://www.shopcasio.shriro.com.au/products/f91w-1) • [13](https://thenextweb.com/news/how-the-casio-f-91w-became-the-worlds-most-versatile-and-dangerous-watch). In practice units run tighter: one reviewer's watch, checked weekly against NIST time over fourteen months, ran about 8 seconds fast per month on average, well inside the specification and competitive with quartz watches costing ten times as much[12](https://thetestedhub.com/reviews/casio-f-91w/).
**Battery life.** The CR2016 cell is rated for about 7 years, on the stated assumption of 20 seconds of alarm operation and 1 second of light use per day[6](https://www.manualslib.tech/en-gb/guide/241968/casio-f91w-manual.html) • [10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w). One review reports batteries lasting at least seven years and sometimes ten[16](https://juiceonline.com/casio-f-91w/).
**Price.** Current price points vary by market and source: $22.95 retail with sales as low as $16[10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w), £10.99 at Argos[3](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/), £7 ($12) in the BBC's 2011 report[9](https://www.bbc.com/news/magazine-13194733), and "a little over $20" in another report[8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html). The spread reflects both market differences and gradual price rises[17](https://www.howtogeek.com/why-i-use-this-classic-casio-watch-instead-of-a-smartwatch/).
## Variants and related models
**A158W and A168W.** The metal-cased A158WA-1 shares Module 593 and identical functions with the F-91W, differing mainly in case material: resin versus chrome-plated resin. The F-91W weighs 21 g against the A158's 46 g, with widths of 35.2 mm and 36.8 mm respectively, and both carry a 7-year battery life[18](https://straphabit.com/blogs/straphabit-reviews/casio-f91w-vs-a158-watch-review-whats-the-difference).
**Colorways and special editions.** Named variants include the F-91W-3, F-91WG-9Q, the F-91WM series, translucent "Jelly" F91WS models, minimalist F-91WB models, and an F91WPC-1A PAC-MAN collaboration priced at about $60[10](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w). Casio currently lists the F-91WPC-1A with the same 38.2 × 35.2 × 8.5 mm case and 21 g weight, a bio-based resin band, and unchanged CR2016 battery life and ±30 seconds/month accuracy[19](https://www.casio.com/intl/watches/casio/product.F-91WPC-1A/).
**F-91WF.** The fabric-strap F-91WF replaces the resin band with one made from recycled PET that Casio says resists scratches and stains, keeping the core specs unchanged: 35.2 mm case width, 8.5 mm thickness, 30 m water resistance, and a CR2016 rated for seven years[20](https://www.gearpatrol.com/watches/casio-f-91wf-united-states-availability/) • [21](https://lenouveaureveil.com/en/casio-f-91wf/). It launched in black (F-91WF-1A), navy (F-91WF-2A), and olive green (F-91WF-3A)[21](https://lenouveaureveil.com/en/casio-f-91wf/). Casio retained the proven module rather than adding [Bluetooth](https://www.edgepedia.org/bluetooth), radio-controlled synchronization, solar charging, or advanced sports functions[21](https://lenouveaureveil.com/en/casio-f-91wf/).
**F-B100W.** The Bluetooth and step-counting derivative F-B100W keeps the F-91W's design but adds an accelerometer and Bluetooth, cutting battery life from about seven years to about two. Without a phone connection its stated accuracy is ±15 seconds a month, and it adds 5 alarms, 200 lap/split stopwatch records, and a 60-minute timer against the F-91W's single alarm and no timer[8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html).
## Cultural status and reception
Design critic Stephen Bayley, one of the founders of London's Design Museum, called the F-91W a "modest masterpiece"[9](https://www.bbc.com/news/magazine-13194733). The watch has been adopted as an anti-luxury icon by younger generations amid the 1980s fashion revival, with buyers deliberately choosing it in protest at widening wealth divides[11](https://www.watchfinder.co.uk/articles/review-casio-f-91w). Casio itself reports that buyers now include fashion-conscious customers, design enthusiasts, collectors, and younger consumers alongside the traditional affordability-driven buyers[14](https://www.t3.com/luxury/watches/casio-f91w-design-icon-0826).
**Military and everyday use.** The F-91W is popular in regular armies, including Singapore's military service, US Air Force training camps, the [British Army](https://www.edgepedia.org/british-army), and the [Royal Air Force](https://www.edgepedia.org/royal-air-force)[22](https://www.vice.com/en/article/casio-f91w-watch-terrorists-ied-trigger-cost-price/). Gear Patrol reported it as Amazon's number-one selling watch, with a 4.6 rating across more than 50,000 reviews[7](https://www.gearpatrol.com/watches/casio-f-91w-review/). Demand for rare editions with green or gold frames has grown, driven by schooldays nostalgia[9](https://www.bbc.com/news/magazine-13194733).
## Repairability and battery replacement
The caseback is held by four Phillips screws, so a battery swap takes about five minutes with no case press or special tools[15](https://a1make.com/watches/casio-f91w/); another reviewer puts it at a couple of minutes with a small Phillips driver[12](https://thetestedhub.com/reviews/casio-f-91w/). Straps, batteries and complete replacement Module 593 units are widely available commodity parts[15](https://a1make.com/watches/casio-f91w/). Beyond battery and strap, though, nobody repairs an F-91W, because a new one costs less than any repair[15](https://a1make.com/watches/casio-f91w/). The resin band is the design's weak point, tending to break after a few years[17](https://www.howtogeek.com/why-i-use-this-classic-casio-watch-instead-of-a-smartwatch/).
## Recent developments
Several developments postdate 2023. The F-91WF fabric-strap variant became available in the United States at $46 from Casio's website, in black, navy, and OD green[20](https://www.gearpatrol.com/watches/casio-f-91wf-united-states-availability/). The F-91WPC-1A with a bio-based resin band appears in Casio's current catalog[19](https://www.casio.com/intl/watches/casio/product.F-91WPC-1A/). The F-B100W Bluetooth derivative went on sale in Japan on 7 August at ¥8,800 (roughly ₹5,000) and sold out from Casio's own online store the same day[8](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html). Prices have risen over time while remaining in the low tens of dollars[17](https://www.howtogeek.com/why-i-use-this-classic-casio-watch-instead-of-a-smartwatch/), and around the 35th anniversary Casio publicly reaffirmed its policy of not changing the design[14](https://www.t3.com/luxury/watches/casio-f91w-design-icon-0826).
## References
1. [CASIO F91W-1 Black Vintage Digital Watch, Casio Australia (official retailer)](https://www.shopcasio.shriro.com.au/products/f91w-1)
2. [Designing Classics Loved Across Generations, Casio Computer Co., Ltd.](https://note-pr.casio.co.jp/n/ndd63897e6745?hl=en)
3. [Digital Love: The Inside Story of Casio Watches, 50 Years Later, Esquire UK](https://www.esquire.com/uk/watches/a63000992/casio-watches-at-50/)
4. [Casio F-91W, since 1989, Made Since](https://madesince.com/object/casio-f-91w/)
5. [F-91W-1JH, CASIO Japan official product page](https://www.casio.com/jp/watches/casio/product.F-91W-1/)
6. [Casio F91W Manual (Module 593)](https://www.manualslib.tech/en-gb/guide/241968/casio-f91w-manual.html)
7. [Why This $17 Casio Is the Cheapest Watch Worth Buying, Gear Patrol](https://www.gearpatrol.com/watches/casio-f-91w-review/)
8. [Casio F-91W: The World's Oldest And Most Popular Digital Watch Gets Bluetooth, News18](https://www.news18.com/tech/casio-f-91w-the-worlds-oldest-and-most-popular-digital-watch-gets-bluetooth-can-now-count-steps-new-f-b100w-model-launched-10268197.html)
9. [Casio F-91W: The strangely ubiquitous watch, BBC News Magazine](https://www.bbc.com/news/magazine-13194733)
10. [Casio F-91W Review, Teddy Baldassarre](https://teddybaldassarre.com/en-au/blogs/watches/casio-f-91w)
11. [Review: Casio F-91W, Watchfinder](https://www.watchfinder.co.uk/articles/review-casio-f-91w)
12. [Casio F-91W: The Watch Every Budget Buyer Needs, The Tested Hub](https://thetestedhub.com/reviews/casio-f-91w/)
13. [How the Casio F-91W became the world's most versatile (and dangerous) watch, The Next Web](https://thenextweb.com/news/how-the-casio-f-91w-became-the-worlds-most-versatile-and-dangerous-watch)
14. [Why Casio refuses to "fix" the F-91W, 35 years after it was initially launched, T3](https://www.t3.com/luxury/watches/casio-f91w-design-icon-0826)
15. [Casio F-91W, A1Make](https://a1make.com/watches/casio-f91w/)
16. [Casio's F-91W Is a Humble, Anti-Luxury Icon That Won't Quit, Juice Online](https://juiceonline.com/casio-f-91w/)
17. [Why I Use This $20 Classic Casio Watch Instead of a Smartwatch, How-To Geek](https://www.howtogeek.com/why-i-use-this-classic-casio-watch-instead-of-a-smartwatch/)
18. [Casio F91W vs. A158 Watch Review, StrapHabit](https://straphabit.com/blogs/straphabit-reviews/casio-f91w-vs-a158-watch-review-whats-the-difference)
19. [F-91WPC-1A, CASIO official product page](https://www.casio.com/intl/watches/casio/product.F-91WPC-1A/)
20. [Casio's Slick New F-91W Hiking Watches Are Finally Available to Buy, Gear Patrol](https://www.gearpatrol.com/watches/casio-f-91wf-united-states-availability/)
21. [Casio F-91WF: The iconic watch finally gets a new strap, Le Nouveau Réveil](https://lenouveaureveil.com/en/casio-f-91wf/)
22. [Why Terrorists Love Casio's Iconic F-91W Watch, VICE](https://www.vice.com/en/article/casio-f91w-watch-terrorists-ied-trigger-cost-price/)
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*Topic: Encyclopedia › Technology and the built world › Communications and everyday technology › Household appliances and domestic equipment › Lighting and electrical devices*
*Initially written Sep 17, 2026 · Reviewed: Sep 17, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license