Buying guide · Fashion
Simple digital watches
Choosing a Simple Digital Watch: Readability, Fit, Features and Water Resistance
A basic digital watch is about legibility, comfort and battery life. How to read water-resistance markings, and when a backlight or a different strap matters.
Updated October 9, 2026
Short answer
A simple digital watch comes down to how wet it will get, whether you'll read it in the dark, and comfort. A case marked only "Water Resist" with no depth, like the Casio F-91W, suits rain and handwashing, not swimming. If you read the time in the dark, a full backlight is easier than a small side light. Beyond that, battery life and a comfortable strap matter more than extra features.
Water resistance: read the marking, not the word
"Water resistant" means very different things depending on the rating beside it. The ISO standard for water-resistant watches prohibits calling a watch "waterproof." A depth marking comes from a one-time pressure test on new watches, which isn't the same as surviving that activity day after day.
The table shows the common industry convention for what each marking suits. Your watch's own manual is the final word.
| Marking | Generally suits | Not for |
|---|---|---|
| "Water Resist" with no depth (e.g. Casio F-91W) | Rain, splashes, handwashing | Swimming, showering |
| 30 m / 3 atm | Everyday splashes and rain | Showering, swimming |
| 50 m / 5 atm | Showering, shallow swimming | Diving |
| 100 m / 10 atm | Swimming, snorkeling, water sports | Scuba diving |
| Diver's (ISO 6425) | Scuba diving to its rated depth | Saturation diving, unless rated for it |
Readability: display and light
In daylight, most simple digital watches are easy to read. The difference is at night. The F-91W has a small side light that's weak by modern standards. Casio's similar-looking F-105W-1A has an electroluminescent backlight that lights the whole display. If you check the time in the dark, that matters more than any extra function.
Fit and comfort
Light resin watches are easy to forget you're wearing, which is much of their appeal. Resin straps are also the part most likely to wear out, so check that replacement straps are available for the model. If you have larger wrists or prefer a heavier feel, a metal-bracelet digital watch is the alternative, but try the clasp sizing first.
Features and battery
Basic features (alarm, stopwatch, day and date) are standard. More features usually mean more buttons and modes to learn, so choose only what you'll use. Battery life matters more: Casio rates the F-91W's CR2016 battery at about seven years, with frequent use of the light and alarm shortening that. Casio publishes a quick operation guide for the F-91W's module (593) covering time and date setting.
Classic models are widely copied. Buy from a listing sold by the brand or a major retailer, and check the seller at checkout.
Who benefits, who should skip, and when what you have is enough
- Worth buying: you want a light, long-lasting everyday watch so you're not checking your phone for the time, or a simple first watch for a teenager.
- Skip a basic "Water Resist" watch if you swim or work in water. Choose one with a stated depth rating that suits the activity.
- What you have may be enough: if a smartwatch already covers your day, a simple watch mainly adds style and a battery you don't charge.
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Sources and how we checked
F-91W battery, functions and marking come from Casio's documentation and the watch itself, as recorded in our review (manufacturer information). The water-resistance table summarizes a third-party reference, not a manufacturer guarantee. Casio's main website blocked automated access when this guide was written. Advice on choosing a watch is PriceDropIQ's editorial judgment. We have not tested these watches hands-on.
- Manufacturer: Casio — Module 593 (F-91W) quick operation guide (PDF)
- Third-party reference: Wikipedia — Water Resistant mark (ISO 2281, ISO 6425 and common ratings)