“Chronograph” is the most widely used watch complication to measure elapsed time while indicating the current time. While the function makes a watch an essential tool watch, it is also the cool look that it offers, which is why people often choose to don a chronograph timepiece. Take a look at the top 10 factors to consider before you buy a perfect chrono for you. 

Lawyers and others who sell units of time can track billable hours. Or you can pass the time by measuring intervals spent stuck in traffic, watching TV commercials, or waiting for the doctor/dentist. Other uses require that the watch have particular features. For example, most chronographs can’t be operated underwater, and many can’t time hours-long events. Some chronographs are designed to run continuously, while others are not (more on this later). Choose carefully if these are the features you desire.

In-house chronographs are typically integrated, not modular, in design, and a column wheel usually occupies central command (more on these concepts below). In-house movements can offer fine functional finishing, careful adjustment, and the resulting smooth feel of quality. They can also be beautiful to behold. In-house production gives brands the freedom to produce singular designs and offers control over every step in the manufacturing process. Chronographs with in-house movements tend to be rather dear, and service can be costly as well. The service is also likely to take a long time and be performed far away. 

Third-party movements offer their own advantages. Most have been around for a while, or they are based on tried-and-true designs, so they are extremely reliable. Service is relatively inexpensive and can usually be handled without sending your watch overseas. Replacement parts are in ready supply. These movements are generally quite sturdy, and they can be excellent timekeepers. (ETA offers mechanical movements in various grades, and as you move up the quality ladder, the timekeeping improves. The top level is COSC-certified.) 

The third-party movements are produced in large quantities, so they are not exclusive. They exhibit little or no handwork. Their components are often stamped, not milled. They are rarely beautiful to behold. They tend to employ mechanisms designed primarily to reduce costs. Some of these calibres can be found in watches costing from hundreds of dollars to several thousand, even reaching five figures. 

When it comes to chronograph movement design, purists prefer integrated to modular, because the integrated variety is designed to be a chronograph from the ground up. That means all components are optimized for that use. That can be important because a chronograph can be a “heavy” complication that requires significant power to operate. If engaging the chronograph generates a drag the base calibre was not designed to handle, that can affect timekeeping, which means the chronograph can’t measure elapsed time accurately (though most of us would never notice the split-second error). Modular movements, also called sandwich or piggyback designs, begin with a base calibre and add a chronograph mechanism mounted on a separate plate, usually on the dial side. If you want a nice view of the chronograph through the display back, an integrated movement is the way to go.

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Imagine what would happen if you could activate the reset mechanism while the chronograph was running. There are different systems, and each has its supporters and detractors. The traditional system, favoured by purists, is the column wheel, so named because the key component looks like a wheel lying on its side with a series of small, vertical columns rising from it. Each push of a button causes the wheel to turn, and as it turns, the columns, and the spaces in between, move in small increments. This action moves the ends of levers that rest against the column wheel, and the levers control the chronograph’s start, stop and reset functions. Column wheels are traditional, expensive to manufacture and adjust, and difficult to service. They also look great, and they provide a very smooth push-piece feel. In other words, they’re made to order for luxury chronographs. So, if you care about tradition, a nice view through the display back, and the approval of purists, the column wheel is for you.

The column wheel and cam issue orders, but other components further downstream transmit the mainspring’s energy to the stopwatch, and once again, there are competing systems. The traditional system uses horizontal or lateral coupling to transmit energy. When the start button is depressed, a wheel mounted on a moveable bridge or lever slides horizontally to link the fourth wheel, which rotates once per minute, with the chronograph centre wheel, which drives the chronograph seconds hand. The intermediate sliding wheel is required because if the fourth wheel meshes directly with the chronograph centre wheel, the chronograph wheel (and the seconds hand it activates) would run counterclockwise.

The horizontal meshing system is aesthetically pleasing because it enables the owner to watch the chronograph engaging and disengaging. However, meshing teeth can cause the chronograph seconds hand to jump when it starts, and because the teeth used for chronograph coupling have a different shape, or profile, than teeth used for continuous power transmission, regular or continuous chronograph use can cause the teeth to wear. The extra wheels in this system can also sap the mainspring’s energy, affecting the balance wheel’s amplitude, and so, timekeeping. The other main contender in this arena is known as the vertical clutch. Though not as aesthetically pleasing, this system offers some advantages. It reduces chronograph drag, the chronograph seconds hand does not jump when started, and the chronograph can run continuously without causing excessive wear.

In simple terms, in the vertical system, the chronograph is always “in mesh” with the timekeeping wheel train, and a clutch engages and disengages the chronograph. The clutch means smooth starts for the chronograph seconds hand, and the  “always in mesh” feature means that starting the chronograph does not generate significant additional drag. The drawbacks include cost, poor aesthetics, and the fact that the vertical clutch can be difficult to service. If you’re a traditionalist who will happily trade a bit of precision for the joy of watching your chronograph in action, the horizontal coupling system is for you. If you’re more concerned with precise starts and stops, or if you like to leave your chronograph running all the time, consider the vertical clutch variety.

There is a direct relationship between a movement’s frequency and the size of the fractions of a second it can measure. The higher the frequency, the smaller the fractions. So, as the average frequencies for wristwatch movements have increased over the years, chronographs based on those movements have become able to measure smaller and smaller fractions of seconds. Movement frequencies are often expressed in vibrations per hour or vph. This relates to the speed of the balance wheel’s oscillations. Viewed from above, the balance wheel swings back and forth, left and right. Each swing to the left or to the right is a vibration. Each vibration, or beat, causes the seconds hand to make one jump forward.

The most common frequency for modern mechanical movements is 28,800 vph. To calculate how many vibrations that is per second, divide that rate by 3,600, which is the number of seconds in an hour (remember that vph is vibrations per hour). The answer is eight, which means that the movement is capable of measuring time to 1/8 of a second. Similarly, a watch with a frequency of 18,000 vph can time events to the nearest 1/5 of a second. A frequency of 21,600 vph yields an accuracy of 1/6 of a second. A watch with a frequency of 36,000 vph can time events to the nearest 1/10 of a second. If the fellows making 1 Hz or 7,200 vph, movements (they include the companies Grönefeld and Antoine Martin) ever decide to produce a chronograph, it will measure only half-seconds. Having mastered this bit of math, it is important to keep in mind that the movement frequency does not always translate directly to the motion of the chronograph seconds hand. That’s because the manufacturer can use gear ratios to change the rate at which the chronograph seconds hand moves around the dial. A chronograph with a 28,800 vph movement might be (and often is) geared to actually measure 1/5-second increments on the dial, not 1/8-second.

If you need a chronograph that can measure specific intervals, such as 1/10s of a second, pay attention to both the movement frequency and the chronograph seconds track on the dial to make sure they meet your needs.

Anything one watchmaker can invent, another can make more complicated, which leads us to some exotic forms of the chronograph: the flyback and the rattrapante. The flyback, sometimes called the split-seconds flyback, can be used as a traditional chronograph, but a special feature allows the user to stop, reset, and restart the chronograph with a single push of a button, usually the one at 4 o’clock. The flyback’s drawback is that the reset mechanism makes it difficult to get a precise elapsed-time reading. When you depress the 4 o’clock push-piece, the chronograph seconds hand does not pause for you to take a reading – it instantly flies back to zero. If you’re looking at a finish line to judge when to push the button, you can’t also be looking at the watch to get the elapsed time. The flyback is much more useful when measuring fractions of a second is not required. For example, if a pilot has to execute a series of turns at specified time intervals, he can quickly reset and restart the chronograph before making each turn. Another exotic option is the rattrapante chronograph, also known as the split-seconds or doppelchronograph. Rattrapante means “catch up” or “catch again” in French, and doppelchronograph means “double chronograph” in German.

These watches have two chronograph seconds hands, one on top of the other. One, the rattrapante hand, can be operated independently of the other by means of a third push-piece, usually located at 8 or 10 o’clock. The extra seconds hand allows the timing of a second event, or splits within a single event, though with one significant limitation. For example, in a 100-yard dash, you can start the chronograph, push the button at 8 or 10 o’clock when the first runner crosses the finish line, and the button at 2 o’clock when another runner crosses the finish line. The two chronograph seconds hands will show the two runners’ times. Pushing the rattrapante button again causes the rattrapante hand to catch up to the primary chronograph seconds hand, which is how your time splits in a longer race. For example, in a one-mile race, you might press the rattrapante button each time the runner passes a quarter-mile marker, reading the time for that split. After reading the time, you can press the rattrapante button again to reunite the chronograph seconds hands, until the next quarter-mile marker comes up. The limitation is that the rattrapante hand has no minutes counter of its own. So, you can time two events, or split within a longer event, as long as the rattrapante hand does not have to measure more than one minute.

It’s a hard fact of life that some of the best-looking and most popular modern chronographs, and many classic vintage models, do not have a date. Think Rolex Daytona, Omega Speedy Pro, IWC Portuguese, and vintage chronographs from Rolex, Patek Philippe, Breitling, and many others. Some of us want a date display, but the chronograph that has captured our hearts does not have one. That leaves the cell phone option, which, in our view, is acceptable, even for a true watch aficionado. As long as you’re wearing a watch, what you do with your phone is your business.

If you want to find out if you can live without a date display on your wrist, take a daily-wear watch and change the date so it’s wrong. Or, put a tiny bit of tape on the crystal to block the date. If after a week you have not experienced withdrawal, you’re ready for that chronograph sans date.

Adding a scale to a chronograph dial or bezel expands the range of information the timepiece can convey. Think of these scales as primitive apps that increase the chronograph’s usefulness.

One set of scales is based on the relationships between time, speed, and distance – if you know two values, you can calculate the third, and the scale makes the calculation for you. For example, a tachymeter allows you to calculate speed over a known distance, typically kilometres or miles. Most tachymeter scales start at 400, located at about eight seconds on the dial, and end at 60, at 60 seconds, or 12 o’clock. 

The tachymeter can only measure for one minute, and it is typically graduated to show only a certain range of speeds (for example, between 60 and 400 kilometres per hour). The speeds of runners (too slow) and supersonic jets (too fast) fall outside the tachymeter’s range.

A telemeter allows the user to calculate distance based on known speed and time. The scale is graduated using the speed of sound through the atmosphere. The scale allows the user to determine the distance to an event that can be both seen and heard. The two most widely cited examples are lightning and artillery fire. The user starts the chronograph upon seeing the flash of light and stops the chronograph when he hears the sound. The approximate distance to the event can then be read off the scale. Miles and kilometres are the most common units of distance.

Pulsometers and asthmometers work on the same principle to indicate a patient’s pulse or respiration rate, respectively. The scale is typically explained on the dial. For example, it may read “Gradué pour 30 pulsations'' or “Graduated for 5 respirations.” The user starts the chronograph and stops it when the indicated number of heartbeats or breaths has been counted. The seconds hand will point to the number of beats or breaths per minute on the scale.