Search for a "vintage square Casio" and you will land on two references that look, at a glance, like the same watch: the A168 and the A158. Both are steel-bracelet digital squares, both trace back to the 1980s, and both sit at the affordable end of the Casio range. They are not the same watch, and the differences matter more than the price gap suggests.
The short answer
Buy the A168 if you want the larger, more contemporary-looking square with an electroluminescent backlight that illuminates the whole display. Buy the A158 if you want the smaller, flatter, more discreet original with a single-LED light and a slightly more classical shape.
Case size and wrist presence
This is the difference most people actually feel. The A168 has a noticeably taller case profile and a larger overall footprint — around 36–38mm across the body depending on how you measure the resin bezel. The A158 is smaller and flatter, closer to 33–35mm, and disappears under a shirt cuff more easily.
If you have a wrist under about 16cm, the A158 will usually look better proportioned. Above that, the A168 avoids looking undersized. Neither is a large watch by modern standards — that is the appeal.
The backlight: EL vs LED
The A168 uses an electroluminescent (EL) backlight. Press the light button and the entire display glows evenly, usually a pale blue-green. It is genuinely usable in the dark.
The A158 uses a simpler single LED mounted at the side of the display. It throws light across the screen at an angle, which means one corner is bright and the opposite corner is dim. It works, but it is a 1980s solution and it shows.
If you check the time at night with any regularity, this alone decides it.
Bracelet and finishing
Both come on folded-link steel bracelets, and both are lighter and more flexible than a solid-link bracelet. The A168's bracelet is marginally wider to match the larger case. Finishing is comparable — this is not a watch where you should expect brushed-and-polished contrast or screwed links.
Both bracelets are adjustable by removing pins. Both take a standard spring bar if you would rather fit a NATO or leather strap, which is a common and cheap way to change the character of either watch.
Functions
Functionally they are close to identical, and both do the things a cheap digital Casio has always done well:
- Daily alarm
- 1/100-second stopwatch
- Auto-calendar
- 12/24-hour display
- Water resistance rated for splashes and handwashing — not swimming
Neither has world time, neither has a countdown timer, and neither is solar or radio-controlled. Battery life is typically quoted around seven years, which in practice means you will forget it exists until it stops.
Water resistance: read this before you swim
Both the A168 and A158 are rated for everyday splash resistance only. That means rain and handwashing are fine; showering, swimming and diving are not. The pushers are not gasketed for pressure, and the case back is a simple press-fit.
If you want a genuinely swimmable Casio at a similar price, look at the G-Shock range instead, where 200M ratings are standard.
Colourways and variants
The A168 has been produced in a wider spread of finishes — including gold and rose-gold PVD, black IP, and two-tone versions — which is part of why it has become the more visible of the two online. The A158 is most commonly found in plain steel.
Be aware that the suffix on a Casio reference is not decoration. On these models the trailing letters usually indicate the finish and the market the piece was packaged for, so A168WA-1 and A168WG-9 are different colourways of the same watch, not different watches.
Which one should you actually buy?
| If you want… | Choose |
|---|---|
| A usable backlight at night | A168 |
| The smallest, flattest profile | A158 |
| Gold, rose gold or black finishes | A168 |
| The most understated look | A158 |
| A watch for a smaller wrist | A158 |
Both are honest, cheap, well-made watches that have outlasted most of what was sold alongside them. You can browse the current unisex Casio selection to see which references and finishes are in stock.
Frequently asked questions
► Can I swim with a Casio A168 or A158?
No. Both are rated for splash resistance only. Rain and handwashing are fine, but showering, swimming and diving are not. Choose a 200M-rated G-Shock if you need genuine water resistance.
► What is the difference between the A168 and A158 backlight?
The A168 uses an electroluminescent panel that lights the whole display evenly. The A158 uses a single side-mounted LED, which lights one corner brightly and leaves the opposite corner dim.
► Are the A168 and A158 unisex?
Yes. Both are small by modern standards and are sold as unisex references. The A158 is the smaller of the two.
► How long does the battery last?
Casio quotes roughly seven years for both models under normal use, including occasional backlight and alarm use.
