Head-to-Head Comparison

Updated September 5, 2026

Casio F-91W vs Casio MTP-S120L Solar Field

Casio's timepiece meets Casio's field watch

Quick Verdict

The Casio F-91W (Under $50) offers Casio Digital Quartz (Battery) precision in the tier below the Casio MTP-S120L Solar Field ($100–$150). The F-91W measures 35mm and is rated 30m (Splash Resistant). The MTP-S120L Solar Field counters with Casio (Japan) craftsmanship and 100m (10 ATM) water resistance. Both are exceptional watches for their respective tiers.

CasioF-91WUnder $50 Check price CasioMTP-S120L Solar Field$100–$150 Check price

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Casio

F-91W

Under $50

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Casio

MTP-S120L Solar Field

$100–$150

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Specifications Compared

Feature	Casio F-91W	Casio MTP-S120L Solar Field
Price	Under $50	$100–$150
Case Size	35mm	42mm (49 x 42 x 10.9mm)
Movement	Quartz Module 593	Solar-Powered Quartz
Caliber Type	Casio Digital Quartz (Battery)	Casio Tough Solar Quartz
Power Reserve	7-Year Battery	Months on a full solar charge; no battery replacement
Water Resistance	30m (Splash Resistant)	100m (10 ATM)
Crystal	Acrylic	Mineral Crystal
Case Material	Resin	Stainless Steel
Origin	Casio (Japan)	Casio (Japan)

Category-by-Category Analysis

🎨

Design & Aesthetics

Edge: Draw

Casio's design language vs Casio's approach

The Casio F-91W features a Resin case at 35mm with Acrylic protection. The Casio MTP-S120L Solar Field offers Stainless Steel construction at 42mm (49 x 42 x 10.9mm) with Mineral Crystal. Both represent their brand's distinct design philosophy and heritage.

⚙️

Movement & Performance

Edge: Casio

Quartz Module 593 vs Solar-Powered Quartz

The F-91W runs the Quartz Module 593 (Casio Digital Quartz (Battery), 7-Year Battery power reserve) at standard frequency. The MTP-S120L Solar Field uses the Solar-Powered Quartz (Casio Tough Solar Quartz, Months on a full solar charge; no battery replacement reserve) at standard. The F-91W edges ahead on power reserve.

📏

Wearability & Fit

Edge: Casio

35mm vs 42mm (49 x 42 x 10.9mm) — different wrist presence

At 35mm, the F-91W wears more compactly on smaller wrists compared to the MTP-S120L Solar Field at 42mm (49 x 42 x 10.9mm). Water resistance differs: 30m (Splash Resistant) vs 100m (10 ATM).

💰

Value & Cost of Ownership

Edge: Casio

Casio sits in the lower tier

The Casio F-91W sits at Under $50 and the Casio MTP-S120L Solar Field at $100–$150. On the specs that outlast any price: the F-91W uses Acrylic with 7-Year Battery, against Mineral Crystal and Months on a full solar charge; no battery replacement on the MTP-S120L Solar Field. Service intervals are typically 5-7 years for both.

💧

Water Resistance

Edge: Casio

30m (Splash Resistant) vs 100m (10 ATM)

The F-91W is rated to 30m (Splash Resistant) while the MTP-S120L Solar Field handles 100m (10 ATM). The MTP-S120L Solar Field 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.

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Casio

MTP-S120L Solar Field

Choose the Casio MTP-S120L Solar Field if you value Casio Tough Solar Quartz technology, Casio (Japan) heritage, and 42mm (49 x 42 x 10.9mm) proportions. At $100–$150, the Solar-Powered Quartz with Months on a full solar charge; no battery replacement power reserve makes it a compelling choice.

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The Bottom Line

The Casio F-91W and Casio MTP-S120L Solar Field represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Casio delivers Casio (Japan) engineering.

Frequently Asked Questions

For water, the Casio MTP-S120L Solar Field is rated 100 m against 30 m, which is the difference between swimming and diving on one side and splashes on the other. On price, the Casio F-91W sits a band lower (Under $50 against $100–$150), so it is the cheaper way into the category. Neither is better at everything; the spec table above shows movement, case size, water resistance and crystal side by side so you can weigh what matters to you. We do not test units, so this is the makers' data, not a bench result.

The Casio F-91W offers better upfront value, sitting a tier lower at Under $50. However, the Casio MTP-S120L Solar Field may justify its premium with superior finishing, heritage, or resale value.

Both are suitable for daily wear. The F-91W at 35mm with 30m (Splash Resistant) water resistance handles everyday situations. The MTP-S120L Solar Field at 42mm (49 x 42 x 10.9mm) with 100m (10 ATM) is similarly capable. The F-91W uses Acrylic while the MTP-S120L Solar Field uses Mineral Crystal.

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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.