Casio F-91W vs Seiko Prospex 62MAS Modern Re-interpretation
Casio's timepiece meets Seiko's diver
Quick Verdict
The Casio F-91W (Under $50) offers Casio Digital Quartz (Battery) precision in the tier below the Seiko Prospex 62MAS Modern Re-interpretation ($1,000–$1,500). The F-91W measures 35mm and is rated 30m (Splash Resistant). The Prospex 62MAS Modern Re-interpretation counters with Made in Japan craftsmanship and 200m (20 ATM) water resistance. Both are exceptional watches for their respective tiers.
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Specifications Compared
| Feature | Casio F-91W | Seiko Prospex 62MAS Modern Re-interpretation |
|---|---|---|
| Price | Under $50 | $1,000–$1,500 |
| Case Size | 35mm | 40.5mm |
| Movement | Quartz Module 593 | Automatic 6R35 |
| Caliber Type | Casio Digital Quartz (Battery) | Seiko In-House Automatic |
| Power Reserve | 7-Year Battery | 70 Hours |
| Water Resistance | 30m (Splash Resistant) | 200m (20 ATM) |
| Crystal | Acrylic | Sapphire |
| Case Material | Resin | Stainless Steel with Super-Hard Coating |
| Origin | Casio (Japan) | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Seiko's approach
The Casio F-91W features a Resin case at 35mm with Acrylic protection. The Seiko Prospex 62MAS Modern Re-interpretation offers Stainless Steel with Super-Hard Coating construction at 40.5mm with Sapphire. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz Module 593 vs Automatic 6R35
The F-91W runs the Quartz Module 593 (Casio Digital Quartz (Battery), 7-Year Battery power reserve) at standard frequency. The Prospex 62MAS Modern Re-interpretation uses the Automatic 6R35 (Seiko In-House Automatic, 70 Hours reserve) at 21,600 vph (3 Hz). The Prospex 62MAS Modern Re-interpretation offers a longer power reserve.
Wearability & Fit
35mm vs 40.5mm — different wrist presence
At 35mm, the F-91W wears more compactly on smaller wrists compared to the Prospex 62MAS Modern Re-interpretation at 40.5mm. Water resistance differs: 30m (Splash Resistant) vs 200m (20 ATM).
Value & Cost of Ownership
Casio sits in the lower tier
The Casio F-91W sits at Under $50 and the Seiko Prospex 62MAS Modern Re-interpretation at $1,000–$1,500. On the specs that outlast any price: the F-91W uses Acrylic with 7-Year Battery, against Sapphire and 70 Hours on the Prospex 62MAS Modern Re-interpretation. Service intervals are typically 5-7 years for both.
Water Resistance
30m (Splash Resistant) vs 200m (20 ATM)
The F-91W is rated to 30m (Splash Resistant) while the Prospex 62MAS Modern Re-interpretation handles 200m (20 ATM). The Prospex 62MAS Modern Re-interpretation offers superior water resistance.
Our Verdict
Casio
F-91W
Choose the Casio F-91W if you prioritize Casio Digital Quartz (Battery) engineering, Casio (Japan) craftsmanship, and 30m (Splash Resistant) water resistance. At Under $50, it delivers Quartz Module 593 with 7-Year Battery power reserve.
Check Price on AmazonSeiko
Prospex 62MAS Modern Re-interpretation
Choose the Seiko Prospex 62MAS Modern Re-interpretation if you value Seiko In-House Automatic technology, Made in Japan heritage, and 40.5mm proportions. At $1,000–$1,500, the Automatic 6R35 with 70 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio F-91W and Seiko Prospex 62MAS Modern Re-interpretation represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Seiko delivers Made in Japan engineering.
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How This Page Was Made
Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.