Watches

Seiko 5 vs Casio Duro: Which Should You Buy?

These are the two watches recommended more than any others under $100, and they are recommended to completely different people.

By Brijon M. - Published October 2, 2026

The short answer

Buy the Casio Duro if you want a tough, accurate watch for swimming and daily abuse - it has a genuine 200m rating and quartz precision for a third of the price. Buy the Seiko 5 if you want a mechanical watch and the experience of owning one. The Duro is the better instrument; the Seiko is the better object.

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Two answers to two different questions

Ask for a budget watch recommendation anywhere and you will get one of these two names, often both in the same breath. That makes them look like competitors. They are not - they answer different questions, and choosing between them is really choosing which question you are asking.

The Casio MDV106 Duro is a quartz dive watch with a genuine 200m rating, a screw-down crown and a unidirectional bezel, for roughly $40. As an instrument for swimming, travel and hard wear, nothing else near the price competes.

The Seiko 5 SNK809 is a mechanical field watch with an automatic movement, an exhibition caseback and a 37mm case, for roughly $90. It is less capable in water, less accurate, and considerably more interesting to own.

Neither is a compromised version of the other. They are different categories of thing at a similar price.

Quick picks

The short version. Tap any row to jump to the full write-up, or go straight to Amazon to check the current price.

#	Product	Best for	Price
1	Casio MDV106 Duro A genuine 200m dive watch for about $40.	Best if you will get it wet	Check price on Amazon
2	Seiko 5 SNK809 The cheapest proper introduction to mechanical watches.	Best if you want a mechanical watch	Check price on Amazon

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1. Best if you will get it wet

Casio MDV106 Duro

A genuine 200m dive watch for about $40.

200m
Screw-down crown
Unidirectional bezel
Quartz

The three specifications that make a dive watch functional are all present, which is close to unheard of at this price. Add quartz accuracy and the only ongoing cost is a battery every few years.

Replace the strap and it looks considerably more expensive than it is.

What you give up

44mm and thick, so it overwhelms a smaller wrist. Mineral crystal and a strap that needs replacing immediately.

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2. Best if you want a mechanical watch

Seiko 5 SNK809

The cheapest proper introduction to mechanical watches.

7S26 automatic
37mm
Exhibition caseback
Field styling

A real automatic movement, visible through the back, in a case small enough to suit almost anyone. It is the watch that has introduced more people to this hobby than any other.

Treat the 30m rating seriously and it will last for years.

What you give up

30m water resistance - not a swimming watch. No hand-winding or hacking, and accuracy that drifts tens of seconds a day.

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Side by side

What	Cheap	Expensive	Worth paying for?
Movement	Duro: quartz. ~15 sec/month, battery every 2-3 years.	Seiko 5: 7S26 automatic. -20 to +40 sec/day, no battery.	Depends on what you want. Duro for accuracy, Seiko for character.
Water resistance	Duro: 200m with screw-down crown. A real dive watch.	Seiko 5: 30m. Splashes only - not a swimming watch.	Yes, decisively. If you swim, this alone decides it.
Size	Duro: 44mm, thick, wears large.	Seiko 5: 37mm, slim, fits almost any wrist.	Yes. The Duro overwhelms a small wrist; the Seiko does not.
Crystal	Duro: mineral.	Seiko 5: Hardlex - Seiko's own, slightly tougher than mineral.	Barely. Both will scratch eventually; neither is sapphire.
Strap	Duro: poor rubber strap. Most owners replace it.	Seiko 5: poor nylon or bracelet. Most owners replace it.	No - budget $15-20 for a strap on either, and factor that in.
Price	Duro: roughly $40.	Seiko 5: roughly $90.	Yes, and the Duro's price is the strongest thing about it.
Who it suits	Duro: swimmers, travelers, anyone hard on watches.	Seiko 5: anyone curious about mechanical watches, smaller wrists.	This is the actual decision.

Buy the Casio Duro if...

You swim, snorkel or spend time around water. You want a watch you can genuinely ignore. You have a larger wrist and like a substantial watch. You want perfect timekeeping with no attention. Or - and this is a legitimate reason - you want to spend $40 rather than $90 and have $50 left for a good strap and a spare.

The Duro is also the better first watch to give someone, because there is nothing to explain and nothing to maintain.

Buy the Seiko 5 if...

You want to find out whether mechanical watches interest you, and that is the honest reason most people buy this one. It is the cheapest proper route into that, and the exhibition caseback is a large part of why.

Also buy it if you have a smaller wrist. At 37mm it fits where the 44mm Duro does not, and size is the most common reason a watch ends up unworn.

Do not buy it as a swimming watch. 30m means rain and hand-washing, and no amount of careful use changes that.

Or buy both

Together they cost less than a single mid-range watch and cover completely different situations: the Duro for water and hard wear, the Seiko for everything else. That is genuinely the answer a lot of people land on, and it is not a cop-out.

If you are only buying one and still cannot decide, the water question settles it. If you will ever swim in it, take the Duro.

Both appear in our best watches under $100 roundup alongside three other options.

Common questions

+Which is the better watch overall?

The Duro is the better instrument - more accurate, more water resistant, tougher, cheaper. The Seiko 5 is the more interesting object. If you forced a single answer for a general buyer who might swim, it is the Duro.

+Can I swim with the Seiko 5?

No. 30m water resistance means rain and hand-washing. Showering with it is already pushing it, because warm water and steam are harder on gaskets than cold water is.

+Is the Duro too big for a small wrist?

At 44mm and fairly thick, probably - it is the most common complaint about it. The Seiko 5 at 37mm is far easier to wear on a wrist under about 6.5 inches.

+Do I need to replace the strap on either?

Both ship with straps most owners change within weeks. Budget $15-20 for a replacement and treat it as part of the purchase price - it transforms how either watch looks and feels.

+Which holds up better over ten years?

The Duro, almost certainly. Quartz movements run for decades with occasional batteries, while the Seiko's automatic will eventually need a service that costs more than the watch. Neither is a problem if you accept that going in.