Comparison Garmin Forerunner 245 vs Garmin Forerunner 630

Types of sports and medical data collected by the gadget (plus some features of a similar purpose, such as sleep tracking, smart alarms, stress levels and women's calendar). Note that the features from this list can be found not only in specialized fitness trackers (see "Type"), but also in more traditional devices like smartwatches. Here are the most popular options:

— Pulse rate. Heart rate is one of the most important physiological parameters of a person. So that sports training is as effective as possible, the heart rate must be in a certain range (the specific value depends on the purpose of the training and the personal data of the user). And for some illnesses and treatments, a faster or slower heart rate can be an important signal, including a warning of danger.

— Pressure (tonometer). A sensor that measures the user's blood pressure. Note that the accuracy of such a sensor is usually quite low, the measurement error can be 10% or even more; so it will not replace a full-fledged medical tonometer. On the other hand, a gadget with this feature is quite capable of detecting a critical increase or decrease in pressure, which will allow you to take the necessary measures in a timely manner.

— ECG. A sen...sor that allows you to get detailed data about the work of the user's heart. Note that such a sensor is not a full-fledged electrocardiograph — in fact, it is an advanced type of heart rate monitor that can track the features of the heart rhythm. However, even this is enough to detect some dangerous phenomena — for example, atrial fibrillation, which at first is imperceptible to a person — and take appropriate measures in time.

— The blood oxygen. A sensor (the so-called pulse oximeter) that determines the saturation of the blood with oxygen (saturation); at the same time, the measurement is carried out by a non-invasive method — without punctures and other damage to the skin. Like most medical sensors in wearable gadgets, it is not accurate and is not a full-fledged medical device, but it is quite capable of responding to a critical decrease in the level of oxygen in the blood. It is believed that the presence of a pulse oximeter is relevant primarily for certain diseases, when saturation may decrease due to the disease itself or the characteristics of the treatment being taken. However, this feature can also be useful for quite healthy users who often travel at high altitudes — primarily climbers and aeronauts.

— Body temperature. The presence of a sensor for measuring temperature allows you to take measurements without the use of thermometers. Naturally, errors can occur, so a slight deviation from the norm may not be determined, but the device will easily fix a significant increase in temperature.

— T° of the environment. Even though smartwatches are worn on the body, the built-in sensors in them are usually designed to measure the ambient temperature. This information can be useful both for a general assessment of the surrounding conditions, and for specific purposes — in particular, weather forecasting. It is not uncommon for watches with this feature to also have a barometer (see "Navigation").

— Number of steps. The traditional pedometer is a feature for counting the number of steps taken by the user. These measurements usually use data from the accelerometer, and the results are quite accurate: most modern accelerometers are well calibrated and are quite capable of distinguishing tremors during steps from hand waves and other extraneous movements. The exception is trips in land transport: many wearable gadgets perceive shaking as steps, which should be taken into account when evaluating the results.

— Distance travelled. Measurement of the total distance traveled by the user. For this, either data from a pedometer or a GPS module are usually used (see "Navigation"); each option has its own merits. So, the pedometer is cheaper, it can be used even in rooms without windows, where the signal from satellites does not reach, and on simulators like treadmills, where the user does not move relative to the ground. GPS, in turn, gives higher accuracy, especially over long distances, and is not prone to false positives in vehicles. In some advanced gadgets, these methods can be combined — this is not cheap, but it allows you to combine the advantages of both options and achieve maximum accuracy.

— Movement speed. Determining the speed of the user's movement. As with distance travelled, measurement can be done in a variety of ways; see above for more details. Also note here that many gadgets with this feature are able not only to determine the current speed, but also to constantly record its value and display various indicators: the maximum achieved speed, the average value for training, etc.

— Energy spent (calories). Measurement of the number of calories burned by the user in the process of movement. These data are rather approximate, as they are calculated by indirect parameters (speed and range of movement, personal specs of a person, etc.). However, even this accuracy is quite enough to determine the overall effectiveness of training.

— The amount of fat burned. Measuring the amount of fat burned per workout. As in the case of calories (see above), the result of such measurements is quite approximate. However, in fact, absolute accuracy is not required, and fat loss data can be a powerful motivator.

— Activity time. A measurement of the total time during which the user is actively moving. In many models, such metering may provide additional options, such as fixing several periods of activity with breaks between them and determining the ratio between the time of movement and the time of rest.

— Smart alarm. An alarm clock that monitors the user's sleep phases and gives a signal to wake up at the optimal time for this. Human sleep consists of alternating phases, and waking up in the unfortunate phase creates a feeling of lethargy and fatigue, even if there was enough time to sleep. A smart alarm clock avoids such situations; its work is based on tracking the pulse, breathing rate and other parameters that differ depending on the phase of sleep. Note that the deviation of the signal from the set time can be up to half an hour, but this is usually a deviation towards an earlier rise. As a result, the risk of being late with a smart alarm clock is close to zero, and the lack of sleep time is compensated by the optimal moment of awakening.

— Sleep tracking. Sleep quality assessment is based on data from on-board sensors of fitness trackers or smartwatches. In particular, the heart rate monitor controls the number of contractions of the heart muscle, the accelerometer controls the user's movements. A blood oxygen sensor, if available on the wearable, improves the accuracy of sleep quality data collection. According to the readings of the sensors, the moments of entering and exiting the deep sleep phase are recorded. It is during this period that the restoration of the nervous system and the accumulation of energy for the coming day take place. In deep sleep, a person can completely reboot and gain strength, while in REM sleep, brain activity practically does not differ from the state of wakefulness. The sleep quality analysis feature helps you determine the best time to go to sleep and provides personalized recommendations to improve your night's sleep.

— The level of stress. The level of stress of the body allows you to evaluate the metric that determines the variability of the heartbeat — the difference in time between successive contractions of the heart muscle. Respiration rate, maximum oxygen consumption and excess oxygen consumption after exercise are also taken into account. The stress level score gives a clear picture of the user's experience during the day, however, the value of this parameter is in determining the most optimal body regimen for training. A high heart rate variability usually indicates you are in good shape for playing sports, while a low one can indicate fatigue, dehydration, or feeling unwell. All this directly affects the ability to train effectively. There are no clear units for measuring the level of stress — in smartwatches, the parameter is usually shown as a scale from 0 to 100, often indicating the number of hours the body is under stress and the time it takes to recover to a normal state.

— Women's calendar. The tool for tracking the menstrual cycle keeps abreast of the events of the expected dates of the menstrual period, allows you to determine the most favorable days for conception, helps to notice alarming symptoms in time and prevent many diseases in case of cycle disorders. Based on your total cycle length, the device calculates a predicted date for your next period. The women's calendar records cycle dates, fertility windows, and the day of ovulation. By adding your own notes to it, you can track fluctuations in sleep, appetite, fitness, mood changes and predict well-being for a particular day.

In addition to those described above, more specific types of measurements can be found in modern wearable gadgets.

This block contains both various navigation systems ( GPS, Galileo) and auxiliary features for them ( aGPS, GPS tracking, maps, compass, altimeter , barometer). More about them:

— GPS module. GPS satellite navigation module built right into the watch/tracker. The initial purpose of such a module is to determine the current geographic coordinates; but how this information will be used depends on the specific type and model of the gadget. For example, in some devices GPS is used only for measuring the distance traveled and/or speed of movement, while more advanced models support full navigation and are equipped with built-in maps. In addition, this feature is almost mandatory in children's beacons (see "Type") — it is GPS that is responsible for determining the location of the child.

— aGPS. An auxiliary feature that allows you to speed up the start of the main GPS receiver. To work for its main purpose, such a receiver must update data on the location of navigation satellites; Obtaining this data in the classical way, directly from the satellites themselves, can take quite a long time (up to several minutes). This is especially true for the so-called "cold start" — when the receiver starts up after a long break in opera...tion, and the data stored in it has become completely outdated. aGPS (Assisted GPS) allows you to receive up-to-date service information from a mobile operator — from the nearest base station (this feature is supported by most operators nowadays). This can greatly speed up the startup process.

— GLONASS. This system is a Russian alternative to the American GPS. However it provides somewhat less accuracy, so GLONASS support is usually provided in addition to the GPS module. Simultaneous use of two systems, in turn, improves positioning accuracy.

— Galileo. European satellite navigation system, created as an alternative to the American GPS. Note that it is under the control of civilian departments, not the military. With a full fleet of 24 active satellites, the system gives an accuracy of up to 1 m in public mode and up to 20 cm with the GHA service. Working in conjunction with GPS, the Galileo system provides a more accurate position measurement, especially in densely populated areas.

— Maps. The feature of displaying topographic maps of the area with heights, relief and types of vegetation on the clock screen. Preinstalled maps are used for visual GPS navigation without being tied to a smartphone. Often, the ability to display maps is implemented in tactical smartwatches with a focus on tourism.

— GPS tracking. Many watches with the possibility of laying routes have the feature of guiding by the GPS track. At the same time, the wearable gadget acts as a navigator around the area, showing the route on the screen and suggesting where it is necessary to turn in one direction or another. Some smartwatches with a pronounced touristic bias also have a “Return Route” programme that allows you to go back along an already traveled route. In GPS tracker mode, trackpoints are usually recorded automatically based on the selected fixing interval. You can also mark a track point manually at any time.

— Compass. A classic compass is a device that indicates the direction to the cardinal points. Wearable gadgets usually use an electronic compass — a miniature magnetic sensor, the data from which, if necessary, are displayed on the display.

— Altimeter. A feature that allows you to determine the current altitude of the user's location. Note that the principle and format of the altimeter may be different. So, some models use barometer data for height measurements, others use information from a GPS sensor; the height itself can be determined relative to sea level, relative to some reference point, or in any of these ways, at the choice of the user. These details should be clarified separately.

— Barometer. A feature that allows you to determine the current atmospheric pressure. One of the applications of the barometer is weather forecasting: for example, a sharp drop in pressure usually signals the approach of bad weather. In addition, information from this sensor can be used to operate the altimeter (see above); and even if the gadget does not have an altimeter, the height difference between two points on the ground can be easily calculated from the pressure difference between them.

The size of the display installed in the gadget; for round screens, respectively, the diameter is indicated.

A larger screen, on the one hand, is more convenient to use, on the other hand, it significantly affects the dimensions of the entire device, which is especially critical for wearable gadgets. Therefore, manufacturers choose the display size in accordance with the purpose and functionality of each specific model — so that there is enough space on the screen and the device itself is not too bulky.

It is also worth mentioning that screens with a similar size may have different aspect ratios. For example, traditional smartwatches are usually equipped with square or round panels, while in fitness trackers, screens are often made elongated in height.

Screen size in dots (pixels) horizontally and vertically. In general, this is one of the indicators that determine the image quality: the higher the resolution, the clearer and smoother the picture on the screen (with the same size), the less noticeable are the individual dots. On the other hand, an increase in the number of pixels affects the cost of displays, their power consumption and requirements for a hardware platform (more powerful hardware is required, which itself will cost more). In addition, the specifics of using smartwatches is such that there is simply no need to install high-resolution screens in them. Therefore, modern wrist accessories use displays with a relatively low resolution: for example, 320x320 with a size of about 1.6" is considered quite sufficient even for premium watches.

The density of dots on the screen of the gadget, namely, the number of pixels that are on each inch of the panel vertically or horizontally.

The higher the PPI, the higher the detail of the screen, the clearer and smoother the image is. On the other hand, this indicator affects the price accordingly. Therefore, the higher the density of points, the more advanced, usually, this gadget is in terms of general capabilities. However, when choosing a screen, manufacturers take into account the general purpose and functionality of the device; so that even a small number of PPIs usually does not interfere with comfortable use.

The material from which the transparent cover of the display is made.

— Plastic. Inexpensive, moreover, quite durable and impact-resistant material: even with a strong impact, the plastic is more likely to crack than crumble into fragments. At the same time, scratches easily appear on such a surface, and over time it inevitably becomes cloudy. Because of this, plastic is found predominantly in inexpensive wearable gadgets.

— Glass. In this case, it can mean both classic silicate glass (the same as, for example, in windows), and some original types of impact-resistant glass that are not related to Gorilla Glass(see below). Regular glass costs more than plastic, but not by much, and it looks better and stays clear longer due to its scratch resistance. The main disadvantages of this material are fragility and a tendency to crumble into sharp fragments upon impact. Impact-resistant glass types are devoid of this drawback to one degree or another, but they are also more expensive. According to the price category of the gadget, you can quite accurately determine what kind of glass it uses — ordinary or shock-resistant.

— Sapphire. The coating made of synthetic sapphire is used exclusively in premium-class gadgets — this is due to the complexity of its production and, accordingly, the high cost. On the practical s...ide, sapphire is extremely scratch resistant (it is only possible to scratch such glass with a diamond or special tools), but at the same time it is fragile and easily breaks from impact.

— Gorilla glass. A family of shock-resistant glass types created by Corning and widely used in modern electronics, including wearable gadgets. In addition to strength, Gorilla Glass is also distinguished by good scratch resistance, while being relatively inexpensive (by the standards of such a coating), which has led to their popularity. However, the specific properties of such glass depend on its version; Here are the options that are relevant for modern wearable devices:

• Gorilla Glass v3. The oldest current version was released in 2013. Nevertheless, even such a coating is noticeably superior to traditional glass (not to mention plastic) in terms of transparency and scratch resistance.
• Gorilla Glass v4. Version released in 2014. A key feature was that the development of this coating focused on impact resistance (whereas previous generations focused mainly on scratch resistance). As a result, the glass turned out to be twice as strong as in version 3, despite the fact that its thickness was only 0.4 mm.
• Gorilla Glass SR+. The first version of Gorilla Glass, designed specifically for smartwatches and other miniature wearable gadgets; presented in 2016. According to the creators, the scratch resistance of such coatings approaches those of sapphire glass while maintaining the main advantages of Gorilla Glass — high strength and transparency. In general, for this material, superiority over "alternative options" is claimed by 70% in terms of strength specs and by 25% in terms of optical properties.
• Gorilla Glass DX. Another type of glass, specially designed for wearable devices. It was released in 2018 at the same time as the DX+ version (see below). Of the key improvements in Gorilla Glass DX, in particular, increased anti-reflective properties and an increase in the contrast level of the visible image by 50% are announced; the latter, among other things, allows you to reduce the actual brightness and, accordingly, the power consumption of screens without compromising image quality, which is especially important for miniature wearable devices. And this material differs from the DX+ type coating, on the one hand, by lower scratch resistance, and, on the other hand, by higher anti-reflective specs.
• Gorilla Glass DX+. Almost the same as the original version of DX, related to the same specialization — wearable wearable gadgets and other miniature devices. At the same time, DX + has a higher scratch resistance, but has slightly worse anti-reflective specs. Otherwise, these types of coverage are almost identical.

The time that the gadget can work on one battery charge (or the supplied battery) in normal use.

Normal mode, as a rule, means working with a relatively low load. At this time, the display can display some data, and basic functions can also work (counting steps, periodically checking heart rate, etc.), but in any case, power consumption is low. Therefore, the operating time in normal mode can be quite impressive, up to several weeks, or even months. However, when choosing, it doesn’t hurt to also pay attention to the stated time in active mode (see below) — especially if a long operating time is critical, or you plan to use the gadget intensively. The actual autonomy of the device will most likely be somewhere in between these two values, depending on the actual load. If only the time in normal mode is indicated for the gadget, you should choose with a certain reserve.

The time that the gadget is able to work on one charge of the battery in the active mode of use.

For watch-phones (see “Type”), this usually means a talk mode, for other gadgets, an intensive work mode when numerous features and sensors are used and there is a constant exchange of data with a smartphone/tablet. However, the specific understanding of the "active mode" for different manufacturers may vary: some indicate the time at maximum performance (that is, in fact, guaranteed battery life), others — in some kind of "average mode". However, anyway, this is a fairly clear parameter that describes the battery life of a particular model quite well (and is much closer to real indicators than the time in normal mode mentioned above).

Note that for models with a GPS sensor (see "Navigation"), the specifications may additionally specify the time of active operation using such a sensor. See "Operating time (GPS)" for details.

The material from which the body of the gadget is made. Some models are available in several versions, made of different materials — for example, aluminium or steel; for such cases, all available options are indicated in the specs at once.

— Plastic. Plastic is often considered a low-cost option, but this is not true in the case of wearable gadgets: such devices can use different types of plastic, including very advanced, durable and reliable ones. So the overall quality of such a case, usually, directly depends on the price category of the device. The common advantages of all types of plastic are relatively low weight, resistance to moisture, the ability to give the body any colour and shape, as well as low thermal conductivity.

— Metal. Cases made of metal, for which the manufacturer, for some reason, did not specify the specific composition. However, most often in such cases we are talking about aluminium or steel, see below for more details on both. But high-end materials such as gold or titanium are rarely hidden under the modest term "metal" — they are usually indicated directly in the specifications. Anyway, in general, metal cases are somewhat stronger and more reliable than plastic ones, they also look more solid, but they are also more expens...ive.

— Steel. Usually, stainless steel is used for wearable gadgets. It is highly durable and reliable, does not corrode, looks stylish and neat, and is relatively inexpensive — cheaper than many aluminium alloys, not to mention titanium. One of the peculiarities of steel cases is rather heavy weight, but it can be both a disadvantage and an advantage: a massive case creates an additional feeling of reliability and solidity. It should be noted that most gadgets with steel cases have round dials and a traditional design, which is well suited even to a business style, but occasionally there are exceptions.

— Aluminium. Aluminium alloys combine high strength and low weight — much less than steel. But this material is somewhat more expensive. It is also considered well suited for bright youth gadgets, although it is occasionally used in more traditional devices.

— Rubber. A material found in some models of children's beacons and fitness trackers (see "Type"), but almost never used in other types of wearable gadgets. One of the key advantages of rubber is softness, which gives a certain degree of impact protection and makes the case as safe as possible; both are especially important for children's devices. In addition, such a case can be easily made waterproof and even completely sealed, as well as made in any colour. On the other hand, plastic has practically the same advantages (except for softness), and rubber costs a little more (although it is noticeably cheaper than metals).

— Titanium. Titanium alloys are premium materials and are rarely used, mainly in top-tier models of “extreme” gadgets. This material is light and at the same time extremely durable, besides it perfectly holds its shape when struck; however, titanium costs much more than the same aluminium, despite the fact that high reliability is not so often decisive.

— Gold. Gold or gold-plated case turns the gadget into a stylish fashion accessory. Such a case is very expensive, but this cannot be called a disadvantage: the price of the device emphasizes the status of the owner.

— Ceramics. Special high-strength ceramics is another premium material that not only performs a practical function, but also demonstrates the high level of the gadget and the solidity of its owner. On the practical side, in addition to strength and reliability, this material has extremely high scratch resistance, which allows it to retain its looks for a very long time even in not very favorable conditions. At the same time, ceramics do not tolerate strong point impacts.