Casio J-100 Calculator Watch

Casio J-100 Calculator Watch

Famously endorsed by Sting a kajillion years ago, the J-100 is a pretty special watch.

In a lot of ways it was an odd decision by Casio to put a calculator function into a sports/running watch. Watches, on the wrists of runners, have to deal with a lot of sweat so to have 20 buttons means there are 20 ways moisture could get into the delicate circuitboard. These early calculator watches were a reasonable size too, so added extra weight to the wrist that could quickly become annoying to a runner who is already tired.

And I’m yet to meet a runner who wants to perform calculations while they are in the middle of a jog.

Many Casio watches, particularly those sold from Asian countries have moderate to severe corrosion on the backside where sweat has seeped through the plated coating and pitted the case. Making the J-100 in resin only, with a SS back, alleviated that problem so Casio obviously had that in mind. Also, the plastic, or plated buttons were replaced on the J-100 with anodised aluminium (in orange, red or black, depending on the model you bought).

And, practicalities aside, the J-100 Pace Runner is loaded with features.

It has all the standard stuff, time, date, alarm, stopwatch and calculator, but it’s the pacer features where the J-100 really comes into its own.

Once you set your stride length, the watch can calculate elapsed time, distance covered, number of strides, length of stride and speed — all very important to the runner attempting, for example, a four-minute mile.

Casio predicted selling five million of these watches in the US alone and was even featured in a Sports Illustrated article at the time. (Update, this article no longer exists on the Sports Illustrated website so the link is to the article in The Wayback Machine).

And, of course, Sting was a big fan which didn’t hurt 😉 (photo from

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8 Responses to Casio J-100 Calculator Watch

  1. I am willing to pay a large sum of money for a casio j-100 jogging watch that all its functions work. I have been looking high and low for this j-100 jogging watch. 440-257-5944. please respond-wayne thomas

    • Keep an eye on eBay; the J-100 comes up more often than you’d think. In the past month or so there was a NOS one but it was blue and didn’t have a strap – finding a blue strap would be way harder than finding a J-100 in the wild. They don’t sell for huge dollars either so they’re definitely out there. I love all the unique functions this one has, some of which are on other Casio jogging watches, but this is the only one with a calculator.

      • Привет и спасибо за вступление в контакт. Есть ли у вас фотографии часы, и цена которой вы хотите? Спасибо.

  2. My dad bought me one for my 18th birthday in the 80s, had it stolen, wish I could buy another…

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