Garmin Forerunner 645 Music - Unisex 5059-923
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Garmin Forerunner 645 Music - Unisex


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Show Description

Run free: no cords, no chest strap, no wallet. The Forerunner 645 Music stores up to 500 songs and plays them over Bluetooth so there are no cords to hold you back. The Elevate optical heart-rate monitor reads your pulse information straight off your wrist. GPS and an internal accelerometer track running metrics like speed and distance information, turning your movement into data and making sure you get credit for your work in the gym and on the trails. If you're going to carry your phone anyway, pair the 645 with the free Garmin Connect app to review your performance, receive notifications, control certain other apps, and more. Strava live segment integration (requires Strava premium) uses the power of your smartphone to show you nearby segments as you run. On-the-fly integration means that you no longer have to pre-load your segments, though starred segments will still appear like you’re used to.

  • Built-in activity modes for biking, running, walking, swimming (indoor only), strength training (with rep counter), and more (no multisport mode).
  • Download playlists and podcasts via Spotify, iHeartRadio or Deezer streaming services, or drag and drop MP3s from your computer through Garmin Express.
  • Playlists synced from streaming services can be easily updated on your watch when in range of known Wi-Fi networks.
  • Holds up to 500 songs (depending on music quality), or 3.5GB of music data.
  • Lap data can be configured to come through your headphones, letting you know your pace, speed and more.
  • Garmin Pay™ contact-less payment system (coming soon), will let you pay for purchases through convenience of NFC. By linking credit cards to your Garmin account though Garmin Connect, you can make payments with your watch (if supported by your bank).
  • Internet Live Tracking during activities (through a connected smartphone) allows you to share your location and heart rate with friends, family or coaches.
  • Equipped with Garmin’s new lower-profile Elevate™ optical heart-rate monitor, which provides more reliable constant heart-rate data and allows you to train without a chest strap.
  • Optical heart-rate sensors measure changes in blood volume under the skin and work best when worn snugly, 1 to 3 finger-widths above your wrist bone.
  • Firstbeat™ bullet provides physiological metrics including VO2 max, lactate threshold (requires a heart-rate chest strap, sold separately), race predictor, recovery advisor and performance indicator.
  • Strava Segment integration – both pre-loaded and on-the-fly (through connection with your phone) – lets you know when your starred segment is about to begin and shows instantaneous data, not just of your performance in the moment, but also how it compares to your PR and the current KOM or QOM, and then provides results once the segment is complete (requires Strava premium).
  • Navigate through courses created or downloaded through Garmin Connect or Strava.
  • Training status uses data from past workouts to learn your fitness level and tell you whether or not the training you are doing is productive.
  • Broadcasts your heart rate over ANT+ so other devices can pick it up.
  • Through 24/7 activity tracking, Forerunner 645 learns your activity level and helps guide you towards a more active lifestyle.
  • Move bar reminds you to move after being stationary for too long.
  • On-board sleep tracking mode monitors your rest, letting you see your total sleep hours as well as periods of movement and restful sleep in your Garmin Connect profile.
  • Weekly intensity minutes are displayed against the ideal of 150 needed to maintain a healthy life.
  • Intuitive 5-button interface is easy to use in any weather.
  • Automatically sync your data to a paired smartphone running the free Garmin Connect app.
  • Compatible with all smartphones featuring Bluetooth 4.0 (iPhone 4S or higher, and Android 4.3 or higher).
  • Connects with ANT+ and Bluetooth Smart sensors, from foot pods to speed and cadence pods (but not power meters).
  • Connect IQ support allows you to download apps, templates, data fields, watch faces, and other features.
  • Barometric altimeter helps you track your ascents, descents and total elevation changes.
  • Always-on colour display is bright and clear in any conditions.
  • Internal memory stores up to 200 hours of activities. Garmin Connect will store all of your activity data.
  • User-friendly strap changes, thanks to quick-release pins.
  • Rechargeable lithium ion battery lasts up to 12 hours in GPS mode or 5 hours in GPS and music mode, and up to 7 days in smartwatch mode.
  • In the box: Forerunner 645 Music, charging cable and documentation.

Tech specs

Show Tech specs
Ideal for
  • Running
  • Fitness and training
Face material

Polycarbonate is inexpensive and light, with good clarity and wear-resistance. Mineral crystal glass offers greater clarity and significantly greater wear-resistance. Sapphire crystal is better still for clarity and wear-resistance.

Mineral crystal glass
Wrist strap material Silicone
IPX rating

Indicates the degree of protection against liquid. IP X1: Dripping water while in normal operating orientation; IP X4: Splashing water; IP X5: Water jets; IP X6: Powerful water jets; IP X7: Immersion up to 1m ≤ 30 minutes; IP X8: Suitable for submersion as specified by manufacturer.

Built-in memory 4GB
Dimensions 4.3 x 4.3 x 1.4cm
Countdown timer Yes
Stopwatch Yes
Electronic compass

An electronic compass allows the user to view their heading in situations where they are either standing still or moving too slowly for the GPS to detect.

12/24 hour format Yes
  • USB
  • Wireless
Lug width 20mm
Low battery warning Yes
Calorie consumption

Calculated based on data from a heart rate monitor.

App compatibility

An online community where members upload, analyze and share activity data.

  • Garmin Connect
  • Third party apps
Add maps capability

These units allow you to add maps, so you can mark and name waypoints and create routes on your PC, and then upload the map of your choice to your GPS.

Programmable workouts

Want an easy jog? A fast-paced ride? A workout with lots of variety to keep you on your toes? With programmable workouts you can tailor your training to match whatever you are looking for on a particular day.

New lap auto start

Automatically triggers a new lap after reaching a specified difference.

Heart rate monitor Yes
Distance/time alarm Yes
Interval training Yes
Bluetooth Yes
Auto pause

Automatically pauses timer when you stop or go below a specified pace.

Heart rate in real time

Displays beats per minute during activity.

Calories in real time

Displays calorie expenditure during activity, based on heart rate monitor data.

Speed/cadence sensor

Monitors pedalling cadence and measures pedalling strokes per minute.

Sold separately
Battery life 5-160 h
Chest strap Sold separately
Metric/imperial units format Yes
Power meter

Displays output in watts as you ride.

Not compatible
Unit to unit transfer

Shares data wirelessly between compatible units.


A basic set of map data that is included with the GPS. Basemap detail may vary from unit to unit.

Area calculation No
Tide tables No
Battery power indicator Yes
Data card Not accepted
Foot pod

Attaches to your shoe, captures your running data (i.e., pace, distance), and transmits it to your heart rate monitor or GPS.

Sold separately
Touch screen No
Heart rate target zones

Displays heart rate zones during activity.

Barometric altimeter

Barometer function helps forecast weather trends. An altimeter can provide one line of position for location on a topo map, useful if the GPS isn't working.

Coded signal

A coded instrument ensures no interference between your chest strap and your watch, necessary if you are training in busy gyms or trails where other signals may be encountered.

Workout history Yes
Wireless sync Yes
WiFi Yes
Button lock Yes
Batteries Lithium-ion (included)
Haptic feedback Yes
Case diameter 43mm
Virtual partner

Allows user to monitor training goals with either a virtual partner or alarms.

Pause timer

Pauses the timer when slowing or stopping, and automatically resumes when moving again.

Replaceable wrist strap Yes
Pace alarm

An alarm that notifies you if you vary from a pre-set pace.

ANT+ compatible

Ensures seamless digital wireless communication between ANT+ devices. For example, data from an ultra-low power wireless sensor can be displayed on a bike computer or smartphone, then downloaded to a PC, etc.

Made in Taiwan