In this article, we describe and then compare the 4 smart health watches with each other and compare their differences. If you do not have time to read everything, go directly to our Comparison Garmin Forerunner on these 4 models!
Garmin Forerunner 45, 245, 645 and 945: the hit series!
Garmin continues to innovate and brings us from discovery to discovery with each new watch release. With the Forerunner 645 released for 2025, the first of the x45 series, the American brand is integrating an mp3 player into its watch for the first time, catching up with the competition (Apple, Fitbit and Tom Tom in particular). No more bulky Smartphone port to attach to the arm: we can now run light with just a few bluetooth wireless headphones! Other innovative functions are added such as contactless payment Garmin Pay.
In 2024, Garmin completes the series with 3 new watches: the Forerunner 45 and 45S, 245 and 245 Music, and the Forerunner 945. These watches in fact replace 3 existing models, the Forerunner 35, 235 and 935 watches, which they take over the base and add new functions to it, in particular (depending on the model) music, Garmin Pay, a pulse oximeter, incident detection and assistance in the event of an incident.
Buy Garmin Forerunner 45, 245, 65 or 945 at the best price
Forerunner 45: essentials for runners, simple and economical
Forerunner 45: the essentials for running in a light and thin watch
The Forerunner 45 is an entry-level watch replacing the previous model, the Forerunner 35. It is compact, light, at a low price and was designed for casual athletes who are looking for the essentials of running functions. It is more than enough for many athletes who run for fun.
It has a color screen, an optical cardio on the wrist, GPS, smart health connected functions, activity monitoring with sleep and stress level analysis.
It measures VO2max (physical condition), offers a voice coach, the possibility of loading training sessions and interval training. It offers an incident detection and assistance function in the event of an incident.
Available in 2 case sizes (versions 45 and 45S), it adapts to all wrists including thin wrists (from 129 mm in circumference). Here is a watch that knows how to be discreet!
Learn more about the Forerunner 45 and 45S
Buy the Forerunner 45
Forerunner 245 and 245 Music: with GPS navigation and advanced training tools
Forerunner 245 Music: the best compromise for runners
Replacing the Forerunner 235, the Forerunner 245 is the model just above the Forerunner 45. It is available with or without an mp3 player (like the Forerunner 645). After the global success of the Forerunner 235, this is the watch that will most certainly hit the headlines for 2025 and 2023.
In addition to the functions of the Forerunner 45, it offers GPS navigation (GPS track, route tracking, etc.), advanced training tools, a compass, a pulse oximeter for measuring acclimatization to the heat, altitude and efforts.
Its price-performance ratio is excellent. Among the 4 models presented here, it is the best compromise for athletes who need advanced functions for training but who do not have a high budget.
Learn more about the Forerunner 245 and 245 Music
Buy the Forerunner 245
Forerunner 645 and 645 Music: Garmin Pay and more for the mountains
Forerunner 645 Music: with barometric altimeter, payment and music
Released for 2025, the Forerunner 645 is available with or without an mp3 player. Its steel bezel gives it a Fenix 5 look. It will therefore be better in town or at work than a Forerunner 245 or a Forerunner 945.
Its advantage compared to the Forerunner 245 is to carry a barometric altimeter and a thermometer, which makes it more interesting for mountain activities (trail, hiking, skiing, trekking).
It also has the Garmin Pay function, a gyroscope and offers segments and compatibility with Strava. However, it does not benefit from the novelties of the other models in the series: Body Battery, pulse oximeter, incident detection and assistance in the event of an incident, etc.
Buy the Forerunner 645
Forerunner 945: more maps, more complete sports watches for 2025
A complete watch for triathletes with cartography, Garmin Pay, GPS navigation, training tools
The Forerunner 945, successor to the Forerunner 935, is to date (2024) the most complete sports watch on the market.
In addition to the functions of previous models, it offers color mapping and cycle paths of Europe, 41,000 golf courses, an integrated mp3 player, the Garmin Pay payment solution, complete tools for training athletes and more . Its autonomy is also remarkable.
It is a multisport watch, designed for the practice of triathlon. This model is ideal for seasoned athletes, competitors, professionals and fans of statistics and advanced tools.
If your budget allows, this is the ideal sports watch, also available in a triathlon pack with quick assembly kit, additional black strap and 2 cardio chest belts (HRM-Tri and HRM-Swim).
Buy the Forerunner 945
The main differences between Forerunner 45, 245, 645 and 945
Characteristics
45
245
645
945
Price
•
••
•••
••••
Basic sports functions
•
•
•
•
Assistance
•
•
•
Mp3 player
•
•
•
Barometric altimeter
•
•
Advanced training tools
•
•
•
Garmin Pay
•
•
Pulse oximeter
•
•
Cartography
•
True multisports
•
Design and technical characteristics
Garmin offers 4 watches designed primarily for the running (hence the name of the series), the competition (for high-end models) or the triathlon (Forerunner 945). They are therefore light (32 g to 50 g) and all equipped with a comfortable silicone strap.
The Forerunner 645 stands out with its stainless steel bezel that makes it look like a Fenix 5 Plus. The Forerunner 45, the most compact in terms of case size and thickness, is also the most discreet. It was also provided in 2 case sizes (39.5 and 42 mm) to allow people with fine wrists to wear a watch that does not make a juggernaut.
Garmin also ensures that its watches are robust: apart from the entry-level model and its chemically reinforced glass, the other 3 models have an ultra-resistant Corning Gorilla glass.
The 4 watches are equipped with a anti-glare color screen of 208 x 208 px for the entry-level model and 240 x 240 px for the other models. Garmin still does not offer a touch screen, this would have been a plus for the Forerunner 945 and the handling of cards.
Characteristics
45
245
645
945
Case diameter
39.5 to 42 mm
42.3 mm
42.5 mm
47 mm
Thickness
11.4 mm
12.2 mm
13.5mm
13.7mm
Weight
32 to 36 g
38.5g
42.2 g
50g
Display size
26.3 mm
30.4 mm
30.4 mm
30.4 mm
Screen resolution (px)
208 x 208
240 x 240
240 x 240
240 x 240
Touchscreen
No
No
No
No
Color display
•
•
•
•
Glasses
Reinforced polymer
Stainless steel
Reinforced polymer
Glass
Chemically reinforced glass
Corning Gorilla 3
Corning Gorilla 3
Corning Gorilla 3
Sealing
5 ATM
5 ATM
5 ATM
5 ATM
Bracelet size
20 mm
20 mm
22 mm
Tool-free interchangeable strap
•
Bracelet material
Silicone
Silicone
Silicone
Silicone
Autonomy
Garmin significantly improves the autonomy of its latest watches thanks to a new Sony GPS chip less energy intensive. We thus reach 24 h in GPS mode for the Forerunner 245 and 36 h for the Forerunner 945 against only 14 h for the Forerunner 645 which is equipped with the old Mediatek chip.
For long races requiring a long battery life, Garmin offers a Ultratrac mode (energy saving) on 3 of the 4 watches. Only the Forerunner 45 does not benefit from it, but that seems logical for a watch intended for occasional use. This degraded mode (the GPS coordinates and the heart rate are only taken every minute instead of every second) allows to reach 60 hours of autonomy on the Forerunner 945. Note that the Forerunner 645 and the Forerunner 945 have a gyroscope that improves the accuracy of measurements in energy saving mode (the gyroscope detects changes in direction and allows you to extrapolate the GPS track).
Note also that these watches can be recharged without stopping the current recording. Unfortunately, recharging cannot be done with the watch on the wrist since the connector is located on the back of the watch …
Comparison Forerunner 45 vs 245 vs 645 vs 945: autonomy
Model
45
245
645
945
Watch mode
7 days
7 days
7 days
2 weeks
GPS mode
1 p.m.
24h
2 p.m.
36 h
GPS mode with music
6 a.m.
5 a.m.
10 a.m.
UltraTrac mode
Yes, duration NC
Yes, duration NC
60 h
Rechargeable during the activity
•
•
•
•
The sensors
The 4 watches are equipped with a compatible GPS chip GPS, GLONASS and Galileo, of a accelerometer for indoor distance measurements (carpet race), and a wrist heart rate monitoring Garmin Elevate ™.
For precise measurements of the heart rate and associated physiological measurements (VO2max, recovery, calories burned, etc.), it is better to use a chest strap. Each of these watches is compatible with an external belt, but if you want to reuse your HRM-Run belt, you will have to acquire the Forerunner 245 or one of the models above. For use in triathlon, the Forerunner 945 is compatible with the HRM-Tri and HRM-Swim belts.
For triathletes, Garmin offers a triathlon pack consisting of a quick assembly kit (the same as that of the Forerunner 935. You can therefore reuse it if you buy a Forerunner 945), 2 chest belts (HRM-Tri and HRM -Swim) and an additional black bracelet.
The barometer indicates the pressure and its variation. It can detect a change in weather and alert the user if there is a risk of thunderstorm. The barometric altimeter uses the barometer to assess altitude and vertical speed much more accurately than GPS. The Forerunner 645 and the Forerunner 945 are fitted with this. These watches are therefore more suitable for mountain outings (outdoor, trek, trail, hike).
Pulse oximeter measures blood oxygen saturation (SpO2 value). It is used to assess acclimatization to heat, to altitude at exertion and to assess the quality of sleep. This is a plus for high-level training when training at altitudes or temperatures different from the place of competition or for mountaineers who evolve at high altitudes.
Comparison Forerunner 45 vs 245 vs 645 vs 945: the sensors
Characteristics
45
245
645
945
GPS, GLONASS, Galileo
•
•
•
•
Wrist wrist
•
•
•
•
Accelerometer
•
•
•
•
Compass
•
•
•
Barometric altimeter
•
•
Gyroscope
•
•
Thermometer
•
•
Pulse oximeter
•
•
HRM-Dual
•
•
•
•
HRM-Run
•
•
•
HRM-Swim, HRM-Tri
•
Footpod
•
•
•
•
Cadence & speed sensor
•
•
•
•
Bike power sensor (Vector, etc.)
•
Temperature sensor
•
•
•
Connectivity
The 4 watches compared are smart health connected watches. They can be coupled to a Smartphone, to external sensors or to certain objects that can be controlled remotely (camera, etc.). Connectivity is via Bluetooth (connection to a Smartphone), ANT + (for external sensors) or even Wi-Fi (for downloading or listening to music streaming).
Music on the wrist (on-board mp3 player) on 3 models
Formerly exclusive to the Forerunner 645 Music, the mp3 player is now available on the new mid-range and above Garmin watches. This function is however optional (count 50 € more) except on the high-end model. The mp3 player allows you to listen to music from your watch and wireless Bluetooth headphones without having to carry a Smartphone! Garmin offers streaming listening via a paid Spotify or Deezer subscription (you must however use a Smartphone or Wi-Fi access for network connectivity). You can also download your favorite playlists for offline listening during sports.
The Forerunner 245 Music and 645 Music can carry up to 500 songs. The Forerunner 945 offers a capacity of approximately 1,000 songs.
Garmin Pay contactless payment
Garmin Pay is a contactless payment solution that allows you to pay for small purchases using an NFC (Near Field Communication) chip integrated into the watch (as in smartphones and recent bank cards). Garmin Pay is available in participating stores and provided you have a bank card from a participating bank. Even if this solution is still limited, more and more French banks participate in the system (see the list).Garmin Pay allows you to pay for small purchases even without a GPS connection.
To take advantage of this practical function, you will need to acquire one of the high-end models: Forerunner 645 or Forerunner 945.
Access to information (weather, etc.) and control of a VIRB camera
The 4 Garmin watches compared offer all the connectivity, including Smart notifications (call, email and SMS notification), access to calendar, weather and music control on a Smartphone (the Smartphone is used for play the music but the control (on, off, volume control, etc.) is done from the watch). They offer a “Find my phone” and “Find my watch” function. The Connect IQ ™ platform also allows the download of watch faces, widgets and various applications.
Aside from the Forerunner 45, the other 3 models also allow you to refuse an incoming call or answer by an SMS (on Andoid only).
These watches make it possible to be followed on the Internet, for certain models, to benefit from assistance in the event of an incident (see assistance functions below).
Finally, the Forerunner 245, 645 and 945 can control a VIRB camera remotely.
Summary table of the differences between the 4 models
Forerunner 45, 245, 645 and 945 compared: connectivity
Function
45
245
645
945
Smart notifications
•
•
•
•
Answer / reject call with SMS (Android only)
•
•
•
Calendar
•
•
•
•
Weather forecast
•
•
•
•
Smartphone music control
•
•
•
•
On-board mp3 player
•
•
•
Music storage capacity (number of songs)
~ 500
~ 500
~ 500
Garmin Pay payment function
•
•
Find My Phone Function
•
•
•
•
Find my watch function
•
•
•
•
VIRB camera remote control
•
•
•
Functions for training and performance analysis
These functions, which are increasingly present on sports watches, provide invaluable assistance to athletes for training and performance monitoring. Garmin offers a set of more or less sophisticated functions depending on the model. On the mid-range and high-end models, these tools are a serious help for athletes of all levels. We find in particular:
Basic functions: speed, distance, training schedule, interval training, various tools for training and improving your training.
Race dynamics: relevant information to analyze a running outing and improve the following outings
Physiological measures: measurements obtained from heart rate data (VO2max, recovery, lactic threshold, load, etc.)
The exploitation of the heart rate: to work on endurance, power, threshold etc. but also lose fat and monitoring its progress.
The entry-level Forerunner 45 watch offers the essential functions for running, nothing more, but it’s already very good for most casual athletes.
Intermediate models (mid-range 245 and high-end 645) provide many functions and will be more than enough for most athletes looking for advanced training tools. There is very little difference between these 2 models.
The Forerunner 945 brings a few additional functions that will be of particular interest to competitors and triathletes.
Basic functions
Comparison Forerunner 45 vs 245 vs 645 vs 945: functions for training and analysis
Characteristics
45
245
645
945
GPS speed and distance
•
•
•
•
Course recording
•
•
•
•
Personalization of data pages and activity profiles
•
•
•
•
Split training
•
•
•
•
Advanced training
•
•
•
•
Downloadable training programs
•
•
•
•
Race time predictor
•
•
•
•
Audio instructions
•
•
•
•
Auto Lap
•
•
•
•
Manual circuit
•
•
•
•
Configurable circuit alerts
•
•
•
Virtual Partner
•
•
•
Virtual racer
•
•
•
Strava functions
•
•
Automatic and manual multisports
•
Race dynamics
Aside from the Forerunner 45, the other 3 watches provide running dynamics that allow you to analyze your stride and improve your running technique. These measures require the use of an additional accessory, the Running Dynamics Pod, to clip on the belt.
Comparison Forerunner 45 vs 245 vs 645 vs 945: racing dynamics
Characteristics
45
245
645
945
Ground contact time
•
•
•
Balance of ground contact time
•
•
•
Cadence
•
•
•
•
Stride length
•
•
•
Vertical oscillation
•
•
•
Vertical ratio
•
•
•
Physiological measurements
Garmin uses the algorithms of the company Firstbeat to exploit the data of heart rate and to provide many physiological measurements. These data make it possible to closely follow the evolution of the progress made and to optimize its training. The watch uses the optical sensor on the wrist to obtain this information. For more reliable measurements, it is best to use a chest belt.
The Forerunner 945 offers some additional data that will interest top athletes. The value of the lactic threshold, the effort Review (allows to see if the organism is ready for a fast race or if on the contrary, it would be better to do a lighter training to recover), the training load objective (impacts of training on the body over the last 7 days) allow training to be optimized without the need for advanced knowledge.
Comparison Forerunner 45 vs 245 vs 645 vs 945: physiological measures
Characteristics
45
245
645
945
VO2max
•
•
•
•
Race duration forecast
•
•
•
Aerobic training effect
•
•
•
Anaerobic Training Effect
•
•
•
Recovery time
•
•
•
Training load
•
•
•
Training status
•
•
•
Training load target
•
Stress Review
•
Main benefit (Training Effect labels)
•
Lactic threshold
•
Breath rate
•
Heat and temperature acclimation
•
•
The exploitation of the heart rate
In addition to the exploitation of the heart rate and its variability to provide the physiological measures mentioned above, the measurement and analysis of the pulse make it possible to assess performance, monitoring its progress, train effectively (work at the threshold , land, increase in VO2max, etc.). Each model measures the heart rate continuously on the wrist or via a chest belt (not supplied). Some models allow you to train at a percentage of your maximum heart rate or reserve frequency.
Comparison Forerunner 45 vs 245 vs 645 vs 945: the exploitation of the heart rate
Characteristics
45
245
645
945
HR zones
•
•
•
•
Heart rate alarms
•
•
•
•
Calories based on heart rate
•
•
•
•
Percentage of HR max
•
•
•
Percentage of reserve CF
•
•
•
Record HR during swimming
•
Sports functions
The Forerunner series has been specially designed for indoor or indoor running. However, each model has other sports profiles such as cycling, swimming. The higher you go upmarket, the more the number of sports on offer. The Forerunner 945 is designed for triathlon and golf but it is also perfect for hiking, trail, outdoor, cycling, exploration. The Forerunner 645, with its advanced tools, is suitable for mountain and outdoor, skiing, in addition to cycling, swimming and running. The Forerunner 45 and 245 models are more intended for running but can be used for cycling, swimming, indoor sports.
The big differences between the 4 models are mainly related to the on-board sensors:
Forerunner 45: most of the functions for running with the possibility of coupling some external sensors to the watch (cadence, speed, footpod).
Forerunner 245: very complete functions for running, cycling, swimming, training programming, GPS navigation. The pulse oximeter takes into account the blood oxygen level in the measurements.
Forerunner 645: the very complete functions of the 245 with height and altitude measurements in addition but without the new features introduced for 2025 (pulse oximeter for example, new sports profiles, etc.).
Forerunner 945: designed for triathlon, it offers all the functions of the models below with, in addition, color mapping and cycle paths of Europe, complete functions for golf and 41,000 preloaded courses, more help tools for athletes, taking into account the blood oxygen level to assess the body’s acclimatization to the effort and to external parameters (temperature, altitude).
Forerunner 45, 245, 645 and 945 compared: sports functions
The 4 watches have an “activity tracker” function for daily monitoring (number of steps taken during the day, calories burned, distance traveled, number of intensive minutes) including a detailed sleep analysis (number of hours , sleep levels, movements), the evaluation of the stress level, the level of effort (the body’s capacity to produce an intensive effort) and, with the exception of the Forerunner 645, a Body Battery function which evaluates the level of bodily energy.
Models 645 and 945, equipped with a barometric altimeter, additionally count the number of climbed stages.
Comparison Forerunner 45, 245, 645 and 945 : activity monitoring
Function
45
245
645
945
Number of steps
•
•
•
•
Step objectives based on previous activities
•
•
•
•
Calories burned
•
•
•
•
Intensive minutes
•
•
•
•
Gravis floors
•
•
Detailed sleep analysis
•
•
•
•
Physical age
•
•
•
•
Monitor Body Battery
•
•
•
Stress measurement
•
•
•
•
Daily effort monitoring
•
•
•
•
Assistance and security
On watches released for 2025 (Forerunner 45, 245 and 945), like the Apple Watch 4 and its fall detection function, Garmin offers a new incident detection function and assistance in the event of incident. The watch can, for example, detect a fall and automatically initiate an assistance request procedure (calling a number, transmitting the name of the user and his GPS coordinates). These functions require pairing with a Smartphone.
The 4 watches compared also have the LiveTrack function which allows to be tracked from a PC or a Smartphone. The Forerunner 945 goes further with the Group LiveTrack function. This function allows a group of users wearing a Garmin watch equipped with this function to know the position of each member of the group.
Forerunner 45, 245, 645 and 945 compared: monitoring and security functions
Function
45
245
645
945
LiveTrack
•
•
•
•
Group LiveTrack
•
Incident detection
•
•
•
Assistance in the event of an incident
•
•
•
Real-time event sharing (Android only)
•
•
•
Our opinion: Garmin Forerunner 45, 245, 645 or 945: which one to choose?
First of all, you should know that Garmin watches are reliable watches, very complete and offering an intuitive interface. With these recent models (Forerunner 645 released for 2025 and other watches released for 2025), there is little risk of regretting its purchase.
You should also know that the Forerunner, as its name suggests, is primarily designed for the practice of running or, for the Forerunner 945, triathlon (a triathlon kit is available for sale and the watch is offered in pack with an HRM-Tri and HRM-Swim belt). If running is not your main activity or you do not have the budget for the Forerunner 945 multisport watch, turn to another model instead.
The design: rather sporty with the exception of the Forerunner 645
Note that with the exception of the Forerunner 645, with a more elegant look, the other models have a rather sporty design. Even if they are intended for 24-hour use, check that this aspect will not cause you concern for use in the city or at work. The Fenix 5 Plus, available in 3 sizes of cases and bracelets in leather, titanium, steel, fabric or even silicone, is perhaps a better choice if you are looking for elegance. It will be just a little heavier than its equivalent, the Forerunner 945.
Budget versus functions offered
Your choice will depend on the budget you wish to allocate and of course the functions sought.
For a large number of occasional athletes, the Forerunner 45 is a very good choice for very correct monitoring and a reasonable price. It is an entry-level model comparable to the watches of the competition but still offering certain advanced functions such as assistance in the event of an incident, incident detection, a Body Battery function, level assessment stress, LiveTrack and more. Another interesting point: the watch is available in 2 case sizes. People with fine wrists will therefore appreciate a more discreet watch to wear.
The Forerunner 245 or 245 Music seems to us a wiser choice: for an additional € 100, the watch offers numerous functions to help athletes, metrics (race dynamics, physiological measurements), a pulse oximeter and, for still 50 € more, an mp3 player (practical if you like to run to music).
A little more expensive, the Forerunner 645 or 645 Music offers a barometric altimeter. This tool is essential for mountain activities (hiking, trail). But apart from this additional sensor and a more elegant look, the watch does not offer much more advantages than a Forerunner 245 if it is not the solution of contactless payment Garmin Pay.
At the top of the range, the Forerunner 945 is today the queen of sports watches. Very complete, even a little too much for the use that most athletes will make of it, it will satisfy demanding athletes, competitors and professionals. It is clearly the watch to buy for triathlon and competition, if you can afford it. Its disadvantage, compared to the Fenix 5 Plus, is that it is offered in a single case size, which can be a disadvantage for people with thin wrists. The Fenix 5 Plus is a better choice from this point of view, pending the next Fenix 6 which should see the light of day for 2025. The Forerunner 945 also benefits from an mp3 player and a payment solution, useful functions .
Autonomy
Autonomy is an important point to take into account in your purchase. That of the Forerunner 45 and the Forerunner 645 (old GPS chip more energy-hungry) is a bit weak, even if the latter model benefits from an UltraTrac mode. If you plan on long outings or if you are unable to recharge your watch frequently, the Forerunner 245 or Forerunner 945 is a better choice with a range of 24 to 36 hours in GPS mode. For greater autonomy, the Forerunner 945 offers an energy saving mode and a gyroscope for better measurement accuracy despite the spacing of the GPS readings.
Training tools
For complete sports aid functions, we recommend the 645 and 945 models which offer similar powerful and very complete functions. The Forerunner 945 offers more tools with its oximeter, the Body Battery function, more physiological measurements. It’s up to you to see if these functions will be really useful for you.
Sports: running and triathlon
Triathletes will not hesitate: the Forerunner 945 must be chosen. It is the only multisport watch among the 4 compared. It allows you to move from one activity to another without stopping the recording. The less sophisticated and less expensive Forerunner 735 XT would be enough for many triathletes. Unfortunately, Garmin does not wish to renew this model … The alternative, as a recent watch, remains the Suunto 5, a mid-range watch offering tools that are easy to use by neophytes. See also our comparison of the best current triathlon watches.
As for the external sensors, the Forerunner 945 is the only watch in the lot that is compatible with the HRM-Tri (triathlon) and HRM-Swim (swimming) chest belts and with a power sensor for the bicycle. A point to take into account for swimmers and cyclists.
In order to help you in your choice, we offer the summary table below.
Garmin Forerunner 45, 245, 645 and 945 compared: how to choose?
Characteristics
45
245
645
945
Price
•
••
•••
••••
Public
Beginners, occasional athletes
Beginners to confirmed
Regular or demanding athletes, seeking performance
Pros, athletes seeking performance, fans of statistics
triathletes
Recommended sports
Running
Running, cycling, swimming
Running, trail, bike, swimming, outdoor, hiking, skiing
