Casio F-91W vs Seiko Prospex Samurai SRPL13
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 Samurai SRPL13 ($500–$1,000). The F-91W measures 35mm and is rated 30m (Splash Resistant). The Prospex Samurai SRPL13 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 Samurai SRPL13 |
|---|---|---|
| Price | Under $50 | $500–$1,000 |
| Case Size | 35mm | 41.7mm |
| Movement | Quartz Module 593 | Automatic Caliber 4R35 |
| Caliber Type | Casio Digital Quartz (Battery) | Seiko In-House Automatic |
| Power Reserve | 7-Year Battery | 41 Hours |
| Water Resistance | 30m (Splash Resistant) | 200m (20 ATM) |
| Crystal | Acrylic | Hardlex Crystal |
| Case Material | Resin | Stainless Steel |
| 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 Samurai SRPL13 offers Stainless Steel construction at 41.7mm with Hardlex Crystal. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Quartz Module 593 vs Automatic Caliber 4R35
The F-91W runs the Quartz Module 593 (Casio Digital Quartz (Battery), 7-Year Battery power reserve) at standard frequency. The Prospex Samurai SRPL13 uses the Automatic Caliber 4R35 (Seiko In-House Automatic, 41 Hours reserve) at 21,600 vph (3 Hz). The Prospex Samurai SRPL13 offers a longer power reserve.
Wearability & Fit
35mm vs 41.7mm — different wrist presence
At 35mm, the F-91W wears more compactly on smaller wrists compared to the Prospex Samurai SRPL13 at 41.7mm. 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 Samurai SRPL13 at $500–$1,000. On the specs that outlast any price: the F-91W uses Acrylic with 7-Year Battery, against Hardlex Crystal and 41 Hours on the Prospex Samurai SRPL13. 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 Samurai SRPL13 handles 200m (20 ATM). The Prospex Samurai SRPL13 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 Samurai SRPL13
Choose the Seiko Prospex Samurai SRPL13 if you value Seiko In-House Automatic technology, Made in Japan heritage, and 41.7mm proportions. At $500–$1,000, the Automatic Caliber 4R35 with 41 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Casio F-91W and Seiko Prospex Samurai SRPL13 represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Seiko delivers Made in Japan engineering.
Frequently Asked Questions
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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.