Seiko's first calculator wristwatch, the C153

Today's watch is one with a special place in watch history - it was Seiko's first calculator wristwatch! It was only beaten by a few months by Citizen from being the world's first LCD calculator watch. It may also be the watch that takes me over 30,000 pageviews!

The Seiko C153 was first released in 1977. It has a fully functional calculator and number pad which was operated with a small stylus. The calculator features all of the normal calculator watch features, but has memory, square root, and percentage functions which are rarely seen on modern calculator watches! The calculator function is displayed along the top line of the 2 row LCD display and can handle 8 digits.

When not in calculator mode, the top line has date and seconds, with the time on the bottom 4 digit line on the LCD. There are no other modes apart from the calculator. There is a light bulb to read in the dark though. Time adjustment is slightly unusual in that you need to pull out the middle button to put it in adjust mode.

This particular model is the C153-5011 version which was released in 1978 (so maybe I exaggerated a little with the blog post title). The watch has its original strap which has a part number of XGB 460.

Mint condition versions of this watch can make over $1000, and even a moderate condition one can easily go for $300 to $400. My one has a slightly faded LCD which is likely caused by aging of the polarizing filter (maybe due to sun or high temperature damage).