How long do G-Shocks last? The battery, the resin and the module run on three different clocks

Why Casio gives no number

Casio's operation guides state a power supply, an approximate battery operating time with the usage conditions behind it, an accuracy figure and sensor ranges. They do not state a service life for the watch. Any site that tells you "a G-Shock lasts 20 years" is reporting anecdotes, which is fine as anecdote and useless as a spec. We will show you the four clocks instead, each with Casio's own figure where one exists.

Clock one: the coin cell

On a non-solar G-Shock the battery is a coin cell. The spec sheets give the DW-5600E a CR2016 rated about five years, the GA-100 a CR1220 rated about two, and the GG-B100 Mudmaster a CR2025 rated about two. Heavy backlight and sensor use shortens all of those; Casio's guides say so explicitly. When the cell dies the watch stops, you or a watchmaker open the back, swap the cell, reseal, and the clock restarts. Over a decade that is two to five cells on the square and about five on the GA-100. It is the cheapest power system on this site and the most serviceable.

Clock two: the solar cell

On a Tough Solar G-Shock the power is a solar panel and a rechargeable cell. Casio's operating-time figures are for the watch in the dark from a full charge: about 8 months on the Rangeman GW-9400, 6 on the Mudman GW-9500 and Mudmaster GWG-2000, 10 on the GW-M5610U. On a wrist that sees light, the cell stays topped up and those months never elapse. The rechargeable cell does age over years; when it finally holds less charge, it is a watchmaker-replaceable part, covered on G-Shock solar battery replacement. Casio's guides also warn that frequent illumination and the auto-light run the cell down faster, which is the one habit that shortens a solar G-Shock's life.

Clock three: the resin

Clock four: the module and crystal

The module (the electronics and display) is what Casio's reputation rests on and the part that most reliably outlasts the owner's interest. There is no firmware to expire and no app to lose support. The mineral crystal on every G-Shock we rank except the GWG-2000 scratches slowly from grit; the bezel keeps strikes off it. A hazed crystal is cosmetic until the scratches sit over the digits. The GWG-2000's sapphire takes that clock away entirely.

The G-Shocks built to run longest

How to make yours last

• Turn off the auto-light on solar models; Casio's guides single it out as the battery drain.
• Let a solar G-Shock see daylight a few hours a week; a drawer is the only place its months run out.
• Replace the strap before it cracks; a strap that fails on a trail takes the watch with it.
• Rinse salt and mud off the buttons; the mud-resistant models seal against it, the squares do not.
• Have the gaskets checked when a coin cell is swapped, so 200 m stays 200 m.

The Garmin version of this question is on how long Garmin watches last, and the site-wide list is buy-it-for-life watches.

None of this applies to a counterfeit, and the module number on the caseback settles that question in two minutes: how to spot a fake G-Shock.

Two related questions come up constantly alongside this one. What the resin case and band actually do, and when they give up, is in resin vs steel cases. And whether you can take one in the water without shortening its life is answered in can you swim with a G-Shock.