Est. 1989

The Casio F-91W

A £10 watch worn by presidents, astronauts, and billions of ordinary people. Unchanged for over 35 years. Still in production. Still perfect.

A Brief History

The F-91W was introduced in 1989 as a sucessor to the popular F-87W. It was a small digital watch designed to be cheap and reliable. The watch was so successful in achieving these goals that Casio never felt the need to change it.

The F-91W runs on Casio's Module 593 (later 3180 in some markets), a movement that has been in continuous production for over three decades. The watch's resin case, resin crystal, 7-year battery life, and 30-metre water resistance rating have all remained essentially unchanged since launch.

Designed by Ryūsuke Moriai as his first design for Casio, the case of the F-91W measures 38.2 x 35.2 x 8.5 millimetres. The case is primarily made of resin, with a stainless steel caseback and buttons, with the module number stamped on the caseback. The resin strap is 18 millimetres (0.71 in) at the fitting and 22 mm across the widest part of the lugs. The total weight is 21 grams (0.74 oz).

Whereas official production figures have not been released by Casio, as of 2011 it was estimated that around 3 million F-91Ws were produced each year, putting the total output at well above 100 million watches to date. It is far and away the best selling watch in history.

The F-91W's cultural impact is significant, appearing in countless films (most recently by my memory is the modern masterpiece Morbius, worn by Jared Leto (no doubt much to his chagrin) and TV shows. The watch is worn by people of all walks of life, from politicians to divers, from wealthy to working class.

1989 F-91W launches as successor to the F-87W. Module 593. Still the same module today.
1997 he first variant, the F-91WG adds a gold accent ring and matching hardware to the classic black case.
2010 The F-91WC series arrives, offering the watch in six vibrant colourways for the first time.
2018 The F-91WM series introduces five metallic-finish case options, each paired with a black resin strap.
2020 The translucent F-91WS series launches, exposing the module through a see-through case and strap.
2024 The minimalist F-91WB series refreshes the lineup with a minimalist dial and bio-based resin band.
2025 PAC-MAN collaboration (F-91WPC) released, marking the arcade game's 45th anniversary.
Today Still in production, still the same watch.

Specifications at a Glance

Movement Casio Module 593 / 3180
Case material Resin
Crystal Acrylic Resin
Water resistance 30 metres
Battery life ~7 years (CR2016)
Case dimensions 38.2 x 35.2 x 8.5 mm
Weight 21 g (with strap)
Accuracy ±15 seconds / month
Usage guide & manual Back to the archive