history · 2 min read
The Casio F-91W: how a 1989 digital watch became an icon
Where the Casio F-91W came from, who designed it, what is inside it, and why a small resin watch from 1989 is still in production.
By the F91W team ·
The Casio F-91W is a small resin digital watch that Casio introduced in June 1989 as the successor to the F-87W. More than three decades later it is still in production, still recognisable from across a room, and still one of the simplest ways to put a reliable watch on your wrist.
Who designed the F-91W?
The F-91W was designed by Ryūsuke Moriai, and it was his first project at Casio, according to the Wikipedia entry for the watch. The brief was not luxury. It was a light, cheap, accurate everyday watch. The result is the shape most people picture when they hear “digital watch”: a slim case with chamfered shoulders, a small grey display, a coloured frame around it, and a red WR badge underneath.
What is inside it?
Every F-91W runs Casio’s module 593. That one module explains why the watch has lasted:
- A battery that lasts years. It runs on a CR2016 coin cell that Casio rates at approximately seven years (Casio F91W-1 product page).
- Quartz accuracy. Casio states an accuracy of about ±30 seconds per month.
- The features people actually use. A daily alarm, an hourly time signal, a stopwatch with split time, an auto calendar and an LED light.
The stopwatch counts in 1/100 of a second up to 59:59.99. That is short of an hour, which is plenty for timing a run or a pot of rice.
Why it is still made
The case is 38.2 × 35.2 × 8.5 mm and the whole watch weighs about 21 grams, per Casio’s published specifications. It disappears on the wrist. Resin does not scratch shirt cuffs, and a seven-year battery means you mostly forget the watch is a machine at all.
The design also never needed fixing. Casio has added colourways instead of redesigns. The F-91WG brings gold trim. The F-91WC series puts the same watch in bright resin colours. The F-91WB series simplifies the print for a cleaner face. If you want to tell them apart, our guide to F-91W colourways walks through each one.
The watch that everyone recognises
Part of the F-91W’s appeal is cultural. It has shown up on the wrists of students, engineers, musicians and people who own far more expensive watches and still reach for this one. It does not signal money. It signals that you know exactly what a watch is for.
That is also why it suits customization so well. The case is simple and uniform, so a custom display or finish stands out instantly. Our customized pieces start from exactly that blank canvas.
Quick facts
| Introduced | June 1989 |
| Designer | Ryūsuke Moriai |
| Module | 593 |
| Battery | CR2016, approx. 7 years |
| Accuracy | ±30 seconds per month |
| Case | Approx. 38.2 × 35.2 × 8.5 mm |
| Weight | Approx. 21 g |
Sources: Casio F91W-1 specifications, Wikipedia: Casio F-91W.
