What’s the Difference Between a Chronometer and a Chronograph?

By rolex
June 2, 2021
9 min read

This “chronograph versus chronometer” question is an important one. Positively, the majority of our repetitive perusers at MONOCHROME have the response to this inquiry. However, what might be said about the others, the ones who need to begin their horological venture and are coming to terms with the language? As we actually get posed this inquiry regularly, we believed that it is acceptable to explain the circumstance and to give a response to “what’s the difference between a chronometer and a chronograph?”

Chronometer versus Chronograph – Two completely unique concepts

The first thing to build up while tending to the subject of the difference between a chronometer and a chronograph is that we are discussing two completely various ideas. They are not the equivalent. In any case, they are not inverse. The terms chronometer and chronograph are exact terminologies, with exact definitions.

A chronometer checks the presentation of a watch and vouches that the watch development has been tried and constrained by an authority association, under characterized rules. It has nothing to do with the elements of a watch.

A chronograph alludes to an element of a watch, something it can do, a purported highlight or, in more horological language, a complication. As an update, a complication is any element in a mechanical watch past the basic presentation of hours, minutes or seconds – in this point of view, even the least complex date component is a complication.

What is a Chronometer?

To comprehend why the idea of “chronometer” was developed, we need to return to the rudiments of watchmaking. A mechanical watch, and all the more exactly its development is a piece of miniature mechanics. Like each mechanical motor depending on moving parts, it is influenced by interior and outer variables. On one hand, it is dependent upon contact, to the utilization of oils to lessen the grating and to general mileage. Much the same as the motor of a vehicle, its presentation will, fundamentally, decay after some time. Grating will build, oils will debase and the moving parts will be liable to wear.

A development is additionally dependent upon outer elements, similar to mugginess, heat/cold, pressing factor, attraction or gravity (the purpose for the innovation of the tourbillon… however that’s another subject). As it is a motor it won’t ever have the option to offer 100% execution, regardless of whether at a specific second or during its whole life cycle.

But what provoked the development of chronometry testing? Let’s return to rudiments. What is a watch? A gadget (mechanical for this situation) that shows the time. What is time? A fixed standard, a concurred and found the middle value of estimation of the length of our days, seasons or lives – all dependent on exact computations. In this manner, you have two adversarial ideas battling here: a definitive precision of time and the natural defect of a man-made mechanical gadget. Precision has been and is a progressing fixation for watchmakers, yet actually no human has had the option to pull off 100% exactness in estimating time, constantly, with a watch. Mechanical watches are and consistently will be off base. However, “how inaccurate?” is the issue that prompted the formation of the chronometer.

A chronometer, in its advanced definition, is a watch that has been tested and confirmed to fulfill certain precision guidelines. “Chronometer” isn’t simply a name that any watch brand can print on the dial of its watches. It is an authority classification, characterized by exact principles – including the ISO 3159 guidelines for “Timekeeping instruments – Wrist-chronometers with spring balance oscillator“, which lays down the meaning of the term “chronometer”, depicting the classes, the test program and the adequate least prerequisites for wrist chronometers.

Various nonpartisan authority certificate associations are permitted to test and verify watches, to give them (or not) the authority “chronometer” affirmation. This incorporates, for example, the Observatoire de Besançon in France, the Glashütte Observatory in Germany or the Japan Chronometer Inspection Institute. With respect to watches delivered in Switzerland, just a single authority association is permitted to affirm chronometers: the COSC, or Contrôle Officiel Suisse des Chronomètres.

Only the watches that have finished a progression of assessments characterized by the  COSC are permitted to have the word “chronometer” imprinted on their dials. How does the COSC deal with affirm watches as chronometers? Firstly, developments are shipped off the COSC by brands which need their watches to be ensured. At that point the COSC completes a progression of tests: “The checks performed by the COSC comprise of static tests acted in the lab. Every individual development/watch goes through a battery of tests explicit to every one of the four kinds, for a few successive days, in five positions and at three unique temperatures (8°, 23° and 38°C).

Then, for 15 days (wristwatches and pocket watches), the developments go through day by day tests. Consistently, including ends of the week, the instruments are estimated and reassembled. Based on the estimations, 7 disposal models are calculated. If and just if the 7 measures are met, the development/watch is affirmed as a chronometer. The rules are:

  • average every day rate
  • mean variety in rates
  • greatest variety in rates
  • the difference between rates in flat and vertical positions
  • largest variety in rates
  • variation in rate contingent upon temperature
  • rate resumption

Each of the tests is acted in 5 positions – 3 o’clock, 6 o’clock, 9 o’clock, dial on top, dial on the base. The following are the base prerequisites for a watch to be confirmed chronometer:

The generally natural of the prerequisites (and the least complex to comprehend) is the normal every day rate. only It isn’t sufficiently adequate to make a watch a chronometer, however this reference builds up a day by day deviation pace of – 4 seconds/+6 seconds as a base. This implies that lone mechanical watches with a room for give and take underneath 0,005% can be ensured as a chronometer… You said exact, we say amazingly precise.

What is a Chronograph?

On the opposite of a chronometer, a chronograph has nothing to do with the precision of the development. A chronograph is an extra capacity – a complication – added to the essential showcase (hours, minutes, seconds). If the watch is exact has nothing to do with the term chronograph. The chronograph is what might be compared to the route framework or the warmed seats in a vehicle. It’s a piece of the alternatives list, something more you can add to make your vehicle more commonsense or more comfortable… But it won’t make it more productive or perform better.

What is a chronograph? As indicated by the COSC, chronographs are “instruments furnished with a component enacted by push-pieces and empowering the estimation of a brief timeframe. Such an instrument is known as a chronograph or chronoscope” or likewise a stopwatch. A chronograph is an instrument where an autonomous range seconds hand can be begun, halted, and got back to zero by progressive tension on the pushers (or anything that can impel the chronograph system). In present day watches, it as a rule comprises signs for the slipped by minutes and hours, notwithstanding the seconds.

The term chronograph comes from the old Greek khronográphos, which means “time recording”. However, gráphō has a more exact importance, which is “writing”. Truth be told, the absolute soonest chronographs depended on turning plates covered with paper, on which a pen was in a real sense composing (or recording) the slipped by times. This is the idea that Nicolas Mathieu Rieussec created – and as he was the first to really commercialize this composing instrument, the name chronograph stuck. Be that as it may, he was not the creator of the stopwatch – the first chronograph was imagined by Louis Moinet in 1816, exclusively for working with galactic hardware. See underneath the Rieussec gadget (left) and the Moinet Compteur de Tierce (right).

Modern-day chronographs are standard watches that demonstrate the time just as an extra capacity to gauge brief timeframes. These watches can be perceived by the pushers on their cases (normally two of them, one situated at 2 o’clock, one situated at 4 o’clock) and their dials with 2 or 3 sub-counters. With them, and without influencing the sign of the current time, you can begin an autonomous instrument to record passed times, stop this capacity when the occasion is done and reset the system to begin another planning session.

Mechanical chronographs are complex instruments that require a great deal of innovative work, just as talented watchmakers to be assembled and adjusted.

Can a watch be both a Chronograph and a Chronometer?

Yes and no… To makes things understood (as per the COSC), a chronograph all alone can’t be confirmed a chronometer, as the capacity of a chronograph is to gauge brief timeframes – the span of a specific occasion. As of now, there is no norm to guarantee the precision of a chronograph alone. In the current case, “chronograph alone” implies sports instruments (like stopwatches) that just have a chronograph work, without the sign of the current time. These are not watches essentially, yet basic time-estimating instruments.

As for watches outfitted with a chronograph, they can be chronometer guaranteed in the event that they comply with the necessities we laid out before. In this unique situation, the chronograph is simply viewed as an extra capacity and has no effect on the tests did by the COSC. The lone prerequisite is that the watch – accordingly the estimation of the current time – is acclimated to a high precision.

Various watches right now available are the two chronometers and chronographs. For example, the Rolex Daytona is a chronograph and simultaneously (as all Rolex watches) a high precision chronometer, guaranteed by the COSC. Same goes for the Omega Speedmaster Automatic with the type 9900, the Breitling Navitimer with Caliber B01 , the  Chopard Mille Miglia  or the  Porsche Design Monobloc Actuator . In any case, a chronograph isn’t essentially a chronometer – truth be told, most chronographs aren’t chronometer-certified.


In short, a chronograph is a complication to quantify brief timeframes and a chronometer is a high-precision watch, confirmed by an authority association. They are diverse however not enemy concepts.