Casio G-SHOCK GD-100

The new G-SHOCK GD-100 lineup from Casio features a high brightness LED as the backlight for the digital display.

Casio developed the G-SHOCK brand of watches in 1983 to realize the new concept of a tough watch that would not break even if dropped. Since that time, the brand has continued to evolve, with advanced functions, construction and design all based on shock resistance.

Casio has led the way in introducing electro luminescence (EL) and light emitting diode (LED) technologies for the luminous elements in watches, improving the visibility of the display in dark locations.

The new GD-100 lineup uses a high brightness white LED as a backlight for the digital display, a feature which expresses the toughness that G-SHOCK represents, in the form of bright light.

Casio G-SHOCK GD-100

In addition to EL lighting elements, LED lighting elements are commonly used as backlights for digital watches, but it has been difficult, on the low power available to a watch, to achieve high brightness with LEDs. They also face limitations when it comes to the color of the luminescence.

Casio’s newly developed luminescence circuit drives a high brightness white LED without using any more power than previous backlights. It provides approximately 6 times the brightness of a conventional LED, and achieves outstanding visibility, even in a bright location. Moreover, the watches are highly practical, with a long battery life of approximately seven years.

The GD-100 lineup boasts a comprehensive range of functions including a world time function showing the time in 48 cities around the world, five alarms, a stopwatch, and a countdown timer.

There is also a flash alert function that blinks the backlight with the sound of the alarm or the time-up sound of the timer, and an auto-light function which automatically illuminates the display when the user tilts the watch toward the eyes to check the time.

The body of the watch has a round shape with large, easy-to-use buttons. The face design features five round LCD windows of different sizes all arranged in a row, which give the face a three-dimensional appearance when the high brightness LED lights up.

The lineup includes a model with a sharp looking white LCD readout on a dark background, or inverted LCD.

Technical details



Water Resistance
200 meters

World Time
48 cities (31 time zones, daylight saving on/off) and Coordinated Universal Time; home and local time swapping function

5 independent daily alarms (one time alarm/daily alarm switching); hourly time signal

Countdown Timer
Measuring unit: 1/10-second; Input range: 1 second to 24 hours (1-second increments, 1-minute increments and 1-hour increments)

1/100-second stopwatch; measuring capacity: 23:59’59.99”; split time

Other Functions
Multi-time for assigning Timekeeping Mode in 4 cities with different time zones; full auto-calendar; 12/24-hour format; button operation tone on/off; LED backlight (auto light switch and afterglow, selectable illumination duration: 1.5 / 3.0 second, Super Illuminator); flash alert

Accuracy at Normal Temperature
±15 seconds per month

Battery Life
Approx. 7 years on CR2025

Size of Case
55.0 × 51.2 × 17.4 mm

Total Weight
Approx. 72 g