Watch guides: size, straps, accuracy and care
Lug-to-lug versus diameter, strap widths, how to measure the accuracy of an automatic watch over seven days, and what maintenance it requires.
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.
Case size: the important figure is not the diameter
Everyone looks at the diameter in millimetres, but the person who decides whether a watch suits you is the lug to lug, the distance between the lugs. Rule of thumb: for a 16–17 cm wrist, look for a lug-to-lug measurement of just under 48 mm; up to 50–52 mm if your wrist is over 18 cm in diameter, 36–38 mm It is the classic style and the one that works best on a slender wrist or with a suit, 39–41 mm It’s the most versatile size available today, and anything over 44 mm takes you into the sports watch territory. A 40 mm watch with long, curved lugs looks better on the wrist than a 38 mm one with straight lugs.
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.
Bezel: why the diving bezel only rotates in one direction
The rotating bezel on a diving watch is unidirectional For safety reasons: it can only move anti-clockwise, so that if you bump into it by accident, it can only shorten the calculated dive time, never extend it. That of a GMT is bidirectional and features 24 markings for reading a second time zone. The tachometer A chronograph allows you to calculate your average speed over a kilometre. And on a dress watch, a slim, polished bezel is what makes the case appear smaller and more elegant than it actually is.
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.
All articles in the Watch Guides section (12)
- How to Choose the Right Watch Case Size Guide
- Leather vs Steel vs NATO Straps: 2026 Guide Comparison
- How to Look After Your Watch So It Lasts a Lifetime Tips
- Mistakes to Avoid When Buying a Watch and How to Avoid Them Tips
- How to Set the Time and Date on Your Automatic Watch Tips
- The Hamilton Khaki Field Mechanical on the Wrist: Size, Weight and Everyday Use Review
- The Tissot PRX Powermatic 80 on the Wrist: Size, Weight and Everyday Use Review
- Daniel Wellington Classic 40mm on the Wrist: Size, Weight and Everyday Use Review
- The Seiko Presage Cocktail on the Wrist: Size, Weight and Everyday Use Review
- The Bulova Lunar Pilot Chronograph on the Wrist: Size, Weight and Everyday Use Review
- The Garmin Venu 3 on Your Wrist: Size, Weight and Everyday Use Review
- How to Shorten a Watch Strap at Home Without Damaging It Tips
Frequently asked questions about wristwatch sizes
Can a smartwatch replace a traditional watch?
For training and receiving notifications, yes. As an object in its own right, no: a smartwatch becomes obsolete in three or four years and its battery only lasts a day, whereas a well-maintained mechanical watch can last well over thirty years. Many people end up owning both and switch between them depending on the day.
What size watch suits me best?
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.
How much should a good first watch cost?
In the €100–200 price range, there are options that will last for years, featuring tried-and-tested automatic movements or maintenance-free solar-powered quartz watches. Moving up to the €400–700 price range buys you a better finish, sapphire crystal and movements with a longer power reserve, but not greater reliability.
Do sundials need maintenance?
Virtually none. The cell lasts between 10 and 20 years and the capacitor can be replaced; under normal lighting conditions, even artificial light, they remain charged and retain a reserve of power for months in the dark.
What budget do I need for a wristwatch of this size?
It depends on how you plan to use it: there are good options in the entry-level range, as well as advanced models that are only worth the extra cost if you’re going to make the most of their features. Check the criteria in this guide, work out how you’ll actually use it, and compare the current price on Amazon before making a decision.
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