Reference Guide · Updated on 9 August 2026 · Watch Guide Team

Automatic watches: calibres, accuracy and which ones are worth buying

What movement do you have inside (NH35, Miyota, ETA, Powermatic 80), what level of deviation is normal, and which automatic movements offer good value for money at each price point.

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.

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The gauges that are actually inside

Almost all automatic cars costing less than €500 are fitted with one of these engines: Seiko NH35/4R35 (reliable, hackable, 41-hour power reserve, the standard for affordable watches), Miyota 8215 (cheap, second hand with a slight wobble) or Miyota 9015 (finer and at 28,800 alternations). Moving up, we find the ETA 2824-2 and its equivalent Sellita SW200, and the Powermatic 80 by Tissot, which stands out for its 80-hour power reserve. Knowing the calibre tells you more about the watch than the brand: two watches with very different price tags may share the same movement.

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.

Accuracy: how to tell if your automatic gearbox is working properly

An automatic watch is not a precision timepiece, and you shouldn’t judge it as such. To measure it properly, set it to the same time for seven days in a row treat it as normal and calculate the average daily deviation: within -10 / +30 seconds a day This is within the factory specification for an uncertified calibre. If it falls outside this range, it is almost always corrected by means of a regulation at a watchmaker’s (€30–60), not as part of a repair. A useful tip: the position in which you leave it overnight affects the result, so if it’s running fast, you can leave it face up, and if it’s running slow, with the crown facing upwards.

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.

Value and depreciation: which watches hold their value

Almost all watches are an expense, not an investment, and it’s best to buy them with that in mind. That said, there are clear patterns: models from brands with a rich history and limited production runs retain their value better on the second-hand market, whilst fashion brands lose between a 60 and 80 per cent as soon as they leave the shop. Affordable watches with an established reputation (the classics from Seiko, Casio or Orient) rarely fall much below the initial price range because their starting price is already low. The paperwork, the box and the condition of the strap affect the selling price more than people realise.

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Frequently asked questions about automatic watches

Is a quartz watch or an automatic watch better?

For accuracy and peace of mind, choose a quartz watch: ±15 seconds a month and a battery change every 2–4 years. For long-term value, choose a mechanical watch with a sliding seconds hand and automatic winding, with a tolerance of between –10 and +30 seconds a day and a service every 5–8 years.

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.

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.

Is a GMT watch worth it?

Only if you travel or speak to people in a different time zone frequently: the fourth hand lets you see a second time at a glance. If it’s just for aesthetic reasons, a true GMT function makes the watch considerably more expensive than the same three-hand model, and the function will end up going unused.

How much do I need to spend on an automatic watch?

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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