The Casio F-91W is the most famous cheap watch ever made, and Casio has barely touched its design since 1989. The F-91WB is what happens when they finally do: the same tiny digital watch, but with a cleaned-up minimalist face, fewer printed labels, and a band made from bio-based resin. It asks a simple question. What if the F-91W grew up?
Watch the video above for the full hands-on look, then read on for the specs, what actually changed versus the original, and whether the WB is worth the small premium over the standard F-91W.
What changed: the dial got a haircut
Pick up an original F-91W and the face is busy: blue and red accents, “ALARM CHRONO” lettering, “Lithium” printed under the display, mode labels around the LCD. The F-91WB deletes almost all of it. The face keeps the CASIO name, a small WR mark, and minimal labels for the pushers. The result is a black-on-black watch that reads as a design object instead of a gas station special, even though the case shape underneath is identical.
That one change does a lot of work. The original F-91W looks like what it is, a budget digital from another era. The WB version pairs with normal clothes in a way the original never quite manages, which is the entire point of the “grown-up” framing.
The bio-based resin band
The second change is the strap. The F-91WB’s band is made with bio-based resin, a material produced partly from renewable organic resources rather than entirely from petroleum feedstocks. Casio’s own wording is careful: the material is “expected to help reduce environmental impact.” It is not biodegradable, and it will not break down in a landfill. What it does mean is that some of the carbon in the plastic started life as a plant instead of crude oil.
In the hand, the band feels like a standard Casio resin strap, because that is the point. Same flexibility, same buckle, same fit. You would never know it was bio-based unless someone told you.
Specs and functions
Under the new face, this is the F-91 module everyone knows. Case size is 38.2 x 35.2 x 8.5 mm and the watch weighs just 21 grams, so it disappears on the wrist. You get a 1/100-second stopwatch (measuring up to 59’59.99″ with elapsed, split, and 1st-2nd place modes), a daily alarm, an hourly time signal, an auto-calendar, and 12/24-hour formats. Accuracy is rated at plus or minus 30 seconds per month, and the CR2016 battery is rated for approximately 7 years.
The case is resin with a resin glass crystal, and water resistance is the everyday kind: fine for splashes and hand washing, not a swim watch. If you need a cheap Casio that can actually swim, the W-800H and its 100-metre rating is the better tool.
The backlight: unchanged, for better or worse
Casio did not fix the one thing F-91W owners have complained about for decades. The WB uses the same small LED backlight design as the original, a green LED that lights the display from one side rather than flooding it evenly. It is usable in the dark and that is about the nicest thing anyone says about it. Reviewers of the WB have flagged this consistently: the redesign is cosmetic, and the light is the cosmetic they most wish had changed.
Whether that matters depends on how you use a watch at night. As a daytime watch, it is a non-issue. As a bedside alarm clock replacement, look elsewhere in the Casio catalogue.
F-91WB vs F-91W: which one should you buy?
Mechanically, they are the same watch: same case dimensions, same weight, same functions, same battery life. The decision is about looks and price. The F-91WB typically sells for around US$30, while the original F-91W usually goes for US$15 to $22. You are paying roughly ten dollars for the minimalist face and the bio-based band.
If you want the icon exactly as it has always been, the original is cheaper and the dial clutter is part of its charm. If you have always liked the idea of the F-91W but found the rainbow lettering a bit much, the WB is the version that fixes your one complaint. Collectors, note that the WB also comes in blue, white, and grey colourways if the all-black is too plain.
Frequently asked questions
Is the F-91WB the same size as the F-91W? Yes. Both are 38.2 x 35.2 x 8.5 mm and about 21 grams. Straps and cases are effectively interchangeable in feel.
How long does the F-91WB battery last? Approximately 7 years on its CR2016 cell, the same rating as the original F-91W.
Can you swim with the F-91WB? No. It is water resistant for daily use, meaning splashes and hand washing. It is not rated for swimming or showering.
Is the bio-resin band biodegradable? No. Bio-based describes where the feedstock comes from (renewable organic resources), not how the finished plastic breaks down.
Verdict
The F-91WB is a cosmetic redesign, and it owns that. Casio took the best-selling digital watch in history, removed the visual noise, made the band from a more responsible material, and changed nothing else, including the famously weak backlight. For about ten dollars over the original, that restraint is exactly right. The F-91W did not need more features. It needed a cleaner face, and now it has one.
Check the current price of the Casio F-91WB-1A on Amazon. If the original is more your style, the classic F-91W remains the cheapest ticket into a genuine watch icon.