Seiko C359-5000 Review


Seiko C359-5000 on wrist

The Seiko C359-5000 takes us back to the late ’70’s. Hamilton’s Pulsar – the hugely expensive “touch to operate” watch that launched digital timekeeping – had been cut off at the knees by hundreds of cheap imitators. Seiko took the digital ball, put it on an LCD screen and ran with it, creating dozens of variations on the theme. None so cool as the C359-5000. None so important to me . . .

Seiko C359-5000 and the boys

In 1979, my mother and stepfather lived in Basra, Iraq. My brother (age 14) and I (age 16) lived with our father here in the U.S. Mom and Ed returned to the U.S. for Christmas and brought my brother and me each a special gift, purchased in neighboring Kuwait. It was the Seiko C359-5000 LCD calculator watch.

A watch with a CALCULATOR built right in! A “smart watch” before there was such a thing. In the 1970s, this was “far out, man.” It was a BIG deal and super-high-tech.

When we returned from Christmas break with our Seiko C359-5000s, my brother and I were the shit at high school. Wel . . . at least with the nerdy guys. The girls? Not so much. Our male schoolmates admired the watches for the advanced tech it was at the time. They were expensive, especially for a couple of teenagers. The Seikos were $150 each, or $550 in 2021 dollars.

The calculator buttons on the Seiko C359-5000 were tiny and required a stylus (a.k.a., a ballpoint pen) and good eyesight. The pens eventually scratched the painted face-plate with the button labels. So what? It was still SO cool!

Mom passed away at age 62 almost fifteen years ago. Our stepfather, Ed, died a few years later.

My brother doesn’t know what happened to his watch. I think I still have mine . . . somewhere. I don’t recall if the Seiko C359-5000 just needed a battery when I stopped wearing it decades ago, or if quit working altogether. I put it away . . . somewhere.

After turning my house upside down and failing to find it (more than once), I became obsessed with replacing it. I set up an alert on eBay. I received daily emails about examples for sale. Many of them were “parts” watches. Most looked like they were substituted for tin cans behind a wedding getaway car.

The very few listed in good to excellent condition were sketchy listings from places like Romania and Pakistan.

I’m comfortable sending hundreds of dollars to Romania hoping I get the advertised watch (if any) in what appears to be a stock photo. But first I need the $43m promised by a beleaguered Nigerian prince who has a profoundly misplaced trust in me.

I clicked on the alerts daily, only to be disappointed with listings for non-functional pieces of crap. Until I wasn’t. I found a “lightly used” example that has all the functions working. The photos of the watch were well-lit and sharp. Cue heavenly music!

The seller was located in North America. The price? $395 from “Mark-of-Time.” I sent a few . . . well . . . several questions to the eBay seller, who answered promptly. I discovered MOT is a vintage digital watch savant! I figured I better click “buy” now and forever hold my timepiece.

THIS was my grail. I’ve never been so excited about a watch. I’d be able to look at my wrist and think of Mom. Very cool.


Receiving the watch was a thrill re-lived 42 years later. Except for one scratch on the black calculator keyboard area beneath the “+” and “x” buttons (evident in the eBay listing photos), the Seiko C359-5000 was in remarkably good condition for a 42-year-old digital watch.

I sent a thank you message to Mark-of-Time. I asked him to let me know if he ever came across a similarly good example. I’d like one for my brother. He promptly replied. “I’ve got another one in even better condition.” He listed it on eBay and immediately alerted me, so I could be the first to the “buy” punch. The second Seiko was virtually pristine. Done and done for $600.Seiko C359-5000 surprise gift

I sent the first C359-5000 to my brother as a surprise gift. I disguised in a travel watch box (from Rothwell on Amazon) and sent it off to my brother.

I couldn’t be there to see his reaction, so I asked him to send me a video opening the box. He thought it might be a watch (since we share the passion), but he didn’t see this one coming. When he opened the box he screamed, “No WAY!” Mission accomplished. He loves it.

By today’s standards, the C359-5000 is a small watch: 35mm (W) x 38mm (L) x 10mm (H). It’s lightweight at 66 grams.

The bracelet is quite handsome, but which kind is it? My first thought was “flattened beads of rice.” Others on the WUS forum colorfully dubbed it the “escalator bracelet.” One called it a “fine link bracelet.”

Seiko C359-5000 bracelet

The sliding clasp can be positioned at the right length and then locked into place. It’s very comfortable; no hairs were pulled in the making of this review.

The Seiko C359-5000 operates on a single 395/399 or SR927W button battery. It’s easily accessed through a dedicated hatch on the back of the watch.

The night light is weak by today’s standards and barely illuminates the display (possibly due to age). The most common part of the Seiko C359-5000 to be “boogered up”: the calculator button faceplate. The buttons require an improvised “stylus” to operate easily.

I’ll keep mine as flawless as possible; I’ll use my phone’s calculator app should I find a need to use applied math in my mundane daily evolutions. That said, I couldn’t resist using my fingernail to operate the buttons just once (I swear!) to reminisce about another teenage fascination.  (See photo at top of this post.)

The Seiko calculator watch also provides an alarm and hourly chime. There’s a visible speaker “grill” to the left of the calculator buttons highlighted with white painted lines, which are easily worn or scratched. The tone is quite loud compared to today’s muted Casio watch alarms. 

When I found a near perfect example of the Seiko C359-5000 of my childhood memories, I realized it was my true grail watch. For a mere $400 – instead of ~$57k++ for the Rolex Daytona (at today’s grey market prices) – I achieved horological nirvana. Better yet, I created another connection with my late mother and stepfather. And I was able to make that happen for my brother.

Model: Seiko C359-5000
Retail price:
$395 / $600 from “Mark-of-Time”

Stainless steel.
Crystal: Mineral glass.
Strap / Bracelet: Stainless steel.
Display: LCD Digital Hours : Minutes : Seconds with day of week.
Functions: 12H format digital time, Day / Date, Alarm, hourly chime, calculator.
Dimensions / weight: 35mm (W) x 38mm (L) x 10mm (H). 66 grams.
Movement: Quartz
Accuracy: +/- 20 seconds per month.
Water resistance: “Water resistant” (no depth rating).
Battery life: Unknown.

RATINGS (out of five stars):

Design * * * * *
Of the era (and since), I think this is the most attractive calculator watch.

Legibility * * *
Digits are average size, which means a bit hard to read for those with older eyes. Night light is weak.

Comfort * * * *
The fine-link steel bracelet is flexible and very comfortable – almost unnoticeable on the wrist. Someone with a large wrist may run out of room on the adjustable clasp.

Overall * * * * *
The cool and nostalgia factors are hard to beat with this one.  The challenge is finding a decent example for sale.

The Truth About Watches is a fully independent website No commercial consideration provided by the manufacturer or seller. No payment for links.


  1. This is a cool story and reminds us that objects can be important to us and do provide meaning. Thanks for sharing and beats Hodinkee by a mile. Unfortunately, every casio and timex I’ve ever owned I broke within a short amount of time as a kid, thus my aversion to watches for a long time. Also, they do leave a bad tan.

  2. Two things…

    1) I’ve added mark-of-time to my Saved Sellers list. He’s got some sweet stuff for sure.

    2) Loud beeps – oh man that’s so true, old digital watches are crazy loud compared to today’s offerings. I have a first gen (1986, pre-Indiglo) Timex Ironman that often scares the crap out of me with it’s hourly beeps.

    Great write up. I enjoyed riding along on your nostalgic/nerd journey.

  3. The more mainstreamed Marty McFly calculator watches were more my era, and I’ve been considering a new one for utterly irrational reasons.

    Earlier digital watches, really all digital watches less the hypebeast collector stuff, is always used and consumed. Ephemeral in nature, nobody preserves them in their time and thus they become the perfect collectible as everyone remembers them, but nobody still has one.

    Usually a totally new technology has first season weirdness where nobody knows what the new product should really look like. Typically there are styling ideas needlessly carried over from the previous technology. For whatever reason, early digitals were spared this and got their own clean, distinct look very rapidly.

        • Congrats and enjoy! I’m really enjoying mine. Wore it the other day. Of all my watches, it’s the most “invisible” on my wrist. I can barely feel it. The bracelet is remarkably nice.

          • I got my new watch c359-5000 to day from Romania 😊👍 In perfekt condition and with tag!👀😊👍

          • Really?!? Wow. Glad to hear it. I’ve seen that watch on eBay for months and months. But, I didn’t trust it. Romania is very well-known to harbor scammers.


          • Hello, I bought seiko C359-5000 from ebay. It’s really a classy watch. One thing I m unable to do is to set the hourly time signal. Alam beeps but not the time sig. Could you please teach me how to set the hourly time signal, to beep every hour. Thanking you in anticipation.
            With regards
            Assam india.

  4. Why did I not notice the awesomeness of the 80085 in the first picture until I had glanced at it 10 times? You, dear author, are incorrigible.

  5. I bought the same watch on ebay with the pen, it did not work so I completely disassembled it and cleaned it with ultrasound and changed the battery. It works perfectly now and I am in love with it!

  6. Hi,

    I bought the same watch and the seconds are going very slow. Does anyone has an idea why this is happening and how to fix it?

    Many thanks
    Daniel/ Sweden

Leave a Reply