Casio: From Calculators to the G-Shock

By Zach Charles, Editor, Time on the Move

Casio came to watchmaking as an electronics company, and that outsider's perspective made it one of the most influential watch brands of the past fifty years. Since its first watch in 1974 it has produced the indestructible G-Shock, the ubiquitous F-91W, the calculator watch, and some of the best-value watches money can buy. By unit volume it is often cited as the world's largest watchmaker.

1946–1957: The Kashio Brothers and the Calculator

Casio began in April 1946, when engineer Tadao Kashio founded Kashio Seisakujo, a small fabrication workshop in Mitaka, Tokyo. His younger brothers Toshio, Kazuo and Yukio joined him. An early hit, a ring-mounted cigarette holder devised by Toshio, funded their real ambition: calculating machines. In 1957 the brothers launched the 14-A , a compact, relay-based all-electric calculator, and incorporated Casio Computer Co. that same year. Calculators, and the electronics expertise behind them, remain the foundation of everything Casio does.

1974: The Casiotron

Casio's first watch, the Casiotron (QW02), arrived in 1974 — a digital watch whose calendar automatically accounted for months of different lengths, the first of its kind. It came at the height of the quartz revolution (see Seiko and the Quartz Revolution), and it signalled Casio's approach: watches as electronic devices that could do more than tell the time.

The Digital Decades

The 1980s were Casio's breakthrough. The C-80 of 1980 made the calculator watch a commercial success; the G-Shock DW-5000C of 1983 introduced shock resistance as a category; and the F-91W of 1989 became one of the best-selling watches ever made. Databank watches stored phone numbers and memos, and the CA-53W calculator watch became a pop-culture icon on Marty McFly's wrist in the Back to the Future sequels.

Pro Trek and Oceanus

Casio's sensor technology produced the ATC-1100 of 1994, its first "Triple Sensor" watch with an altimeter/barometer, digital compass and thermometer, which led to the Pro Trek outdoor line launched in 1995. At the other end of the range, Oceanus launched in 2004 with the OCW-500, billed as the world's first full-metal chronograph combining solar power and radio-controlled timekeeping. Oceanus remains Casio's premium analogue line.

Solar, Radio and Bluetooth

Modern Casios combine three signature technologies: Tough Solar charging from any light source, Multi-Band 6 radio reception that syncs the watch to atomic-clock transmitters in Japan, North America, Europe and China, and Bluetooth smartphone links for automatic time-setting. Together they make many Casios effectively maintenance-free.

The Enthusiast Era

Casio has always had collectors, but the 2019 G-Shock GA-2100 "CasiOak" brought it into the mainstream enthusiast conversation, while affordable pieces like the Duro diver and AE-1200 "Casio Royale" became cult favourites through word of mouth. Casio marked 50 years of watchmaking in 2024.

The Collections Covered Here

• Casio G-Shock — the shock-resistant icon, from the DW-5000C to the Frogman and MR-G
• G-Shock 5600 (Square) — the DW-5600, GW-M5610 and full-metal GMW-B5000
• G-Shock GA-2100 "CasiOak" — the thin octagonal G-Shock
• Casio F-91W — the best-selling digital watch
• Casio AE-1200 "Casio Royale" — the world-time digital
• Casio Duro MDV-106 — the US$70 dive watch
• Casio Calculator & Databank Watches — from the C-80 to the CA-53W

Frequently Asked Questions

When was Casio founded?
In April 1946, when Tadao Kashio founded Kashio Seisakujo in Tokyo. The company was incorporated as Casio Computer Co. in 1957, the year it launched the 14-A calculator.

What was Casio's first watch?
The Casiotron, launched in 1974, a digital watch with the first automatically calculating calendar.

Who invented the G-Shock?
Casio engineer Kikuo Ibe, whose 'Project Team Tough' developed the first G-Shock, the DW-5000C, released in 1983.

What are Pro Trek and Oceanus?
Pro Trek (from 1995) is Casio's outdoor sensor-watch line, descended from the 1994 ATC-1100 Triple Sensor; Oceanus (from 2004) is its premium full-metal solar, radio-controlled analogue line.

What is Casio's best-selling watch?
The F-91W, introduced in 1989, is widely reported to be one of the best-selling watches ever made.

Related Reading

• Casio G-Shock
• Casio F-91W
• Timex: America's Watch
• Explore the Horological History library