Watches: What size watch suits me best?

Short answer

Focus on the lug-to-lug measurement rather than the diameter: under 48 mm for wrists measuring 16–17 cm, up to 52 mm if your wrist is over 18 cm. In terms of diameter, 39–41 mm is the most versatile range, whilst 36–38 mm is the classic choice for a slender wrist or a suit.

Quartz, automatic or manual: which to choose and why

The quartz It is the most accurate and the most practical: it diverts around ±15 seconds per month, it needs nothing more than a new battery every 2–4 years and is more shock-resistant. The automatic It is powered by a wrist movement and deflects between -10 and +30 seconds a day (a COSC-certified calibre has a rate of between -4 and +6), but it is the one with a mechanical soul, a sliding seconds hand and long-term value. The manual It needs to be wound every day and is usually more delicate, which is why it’s used in dress watches. If you’re looking for accuracy, go for quartz; if you’re looking for fine watchmaking, go for an automatic.

Water resistance: what the ATM rating really means

The figure on the box does not represent the actual working depth; it is a static laboratory pressure reading. In practical terms: 3 ATM / 30 m It can withstand rain and splashes, but nothing more; 5 ATM allows you to wash your hands but not to have a shower (the hot water exceeds that pressure and the heat causes the seals to expand); 10 ATM it’s suitable for swimming; and 20 ATM / 200 m That’s the minimum for diving. If you want a proper diving watch, look for the certification ISO 6425, which can be identified by the word printed on the dial DIVER'S alongside depth.

Glass: sapphire, mineral or acrylic

The sapphire is hard 9 on the Mohs scale: Only a diamond or materials containing corundum can scratch it, which is why it’s the best choice if you’re using the watch every day. The mineral (hardness 5–6) can be scratched by sand, keys or cement, although it withstands a single impact better without chipping. The Hardlex Seiko’s is a hardened mineral, somewhere in between. The acrylic It gets scratched just by looking at it, but you can polish it at home with polish in two minutes, giving it that warm, domed look of vintage watches. An anti-reflective coating on the inside makes the dial much easier to read than one on the outside, which wears off.

Steel, titanium and coatings

The standard is the 316L steel, surgical grade, corrosion-resistant and easy to polish. The 904L (which Rolex calls Oystersteel) is slightly more corrosion-resistant and produces a denser polish, but the difference in everyday use is minimal. The titanium It weighs 40 per cent less and is hypoallergenic, making it ideal if you find the weight a problem, although it does show wear more easily. Regarding coatings: the PVD It is a thin layer that eventually wears away at the edges, whilst the DLC It is much harder and lasts for years. The gold plating on cheaper watches usually lasts between 2 and 5 years of daily use.

• Quality of materials and finishes
• Recent verified reviews (including 3–4-star reviews)
• Warranty and returns policy
• Current price compared with its historical average
• Seller's reputation
• Make sure the key features suit your needs (Travelling)

Power reserve – and what happens if you don’t have one

Power reserve is the length of time an automatic watch continues to run after you stop moving it: typically, this is 38–41 hours in traditional calibres, which means that if you take it off on Friday night, it will have stopped by Monday. Modern movements have extended that figure: the Powermatic 80 lasts up to 80 hours and some current calibres at 70. For several automatic watches, a rotary box It keeps them running, although this isn’t essential: leaving it switched off won’t damage the mechanism; it just means you’ll have to set the time again. What is advisable, however, is a service every 5–8 years.

Criterion	Casio G-Shock GA-2100Our choice	Invicta Pro Diver 8926OB
Ideal for	Balanced and general use	Travelling
Strength	Value for money	Specific features
Reviews	Very positive and numerous	Positive
Approximate price	from around €80	from around €50
Recommendation	Our choice	Best alternative
View on Amazon	See price →	See price →

Straps and bracelets: the most cost-effective change

Changing the strap transforms a watch for €20–40 and is the best value-for-money upgrade there is. Measure the width between antlers (18, 20 and 22 mm are the most common) and choose according to your needs: steel for everyday use, skin for washing (never with water), rubber or FKM for sport and summer, and NATO made of nylon for a military look and quick changes. Look for pins made of quick release (quick-release) so that no tools are required. With steel bracelets, the detail that sets the good ones apart from the mediocre ones is the micro-adjustable fastening, which allows you to fine-tune the fit when your wrist swells in the heat.

Glossary: the terms you’ll see in the fact sheets

Lug to lug

The distance between the ends of the lugs. This determines how the watch sits on the wrist.

Power reserve

The number of hours a mechanical watch continues to run without being wound or set in motion.

Hacking

A function that stops the seconds hand when the crown is pulled out, to synchronise to the second.

ISO 6425

A standard certifying a watch as suitable for diving. It is marked ‘DIVER’S’ on the dial.

Alternations

Vibrations per hour of the movement (21,600 or 28,800 are the most common).

Fine-tuning

A clasp system that allows the size of the bracelet to be adjusted in small increments.

Super-LumiNova

Non-radioactive phosphorescent paint that absorbs light and glows in the dark.

So, which one should I buy?

Now that that’s sorted, choosing a watch is simpler than it seems: the Casio G-Shock GA-2100 is the safest bet, whilst the Invicta Pro Diver 8926OB is the better choice if travelling is your priority. When it comes to watches, the price range for decent options starts at around €50, and the best value is usually found around €80; spending more is only worth it if you’re going to make the most of specific features. Check the current price before deciding, as it changes frequently.

Frequently Asked Questions

Can I have a shower whilst wearing a 5 ATM watch?

It’s not advisable. Five atmospheres is measured under static conditions, and the shower jet generates higher pressure peaks; what’s more, the heat causes the seals to expand. For worry-free use with water, you need 10 ATM, and 20 ATM if you’re going diving.

Is sapphire glass worth it?

Yes, if the watch is going to be worn every day: with a hardness of 9 on the Mohs scale, it’s practically scratch-proof in everyday use, whereas mineral glass can be marked by sand or keys. The only advantage of mineral glass is that it absorbs a strong impact better without shattering.

Will an automatic car break down if I leave it standing?

No. Leaving it switched off won’t damage the mechanism; you’ll just need to set the time when you use it again. What it does need over the years is a service, every 5–8 years depending on use.

What width of strap do I need?

Check the distance between the lugs: 18, 20 and 22 mm will fit most watches. If your watch allows it, look for quick-release pins so you can change the strap without tools.

How much does an automatic watch gain or lose per day?

A well-regulated mid-range movement typically runs between -10 and +30 seconds a day; a COSC-certified chronometer runs between -4 and +6. If yours falls outside this range, it can almost always be corrected with a service costing €40–70 at a watchmaker’s, rather than a full repair.

Should I go for the Casio G-Shock GA-2100 or the Invicta Pro Diver 8926OB?

The Casio G-Shock GA-2100 is the most well-rounded option and our default recommendation. The Invicta Pro Diver 8926OB is a good choice if travelling is your priority. As a guide, the price range starts at around €50, and the best value is usually found at around €80.

By the Watch Guide Team · reviewed by

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