Garmin · 2018
Forerunner® 645 MusicSize, Dimensions & Wrist Fit
The Garmin Forerunner® 645 Music sits best on flat wrist widths of about 45–61mm (≈ 12.0–16.3cm wrist circumference). Adjust the slider below to check your wrist.
Affiliate disclosure: As an Amazon Associate, WatchFitTool earns from qualifying purchases. If you buy through links on this page, we may earn a commission at no extra cost to you. Learn more.
The Forerunner® 645 Music in short
The figures that decide whether this watch suits you, pulled out of the full specification sheet further down.
- Rated for 5 hours of use per charge.
- 13.5mm thick. Thicker than 68% of 43mm watches — it will sit noticeably high on the wrist.
- 1.2" (30.4 mm) diameter display.
- Corning® Gorilla® Glass 3 case, Corning® Gorilla® Glass 3 glass.
Does the Forerunner® 645 Music fit your wrist?
Drag the slider to your wrist width and see the Forerunner® 645 Music overlaid at true scale. Lug-to-lug — not case diameter — decides whether a watch overhangs your wrist.
Happy with the fit? Check current availability for the Forerunner® 645 Music.
Check offer2D Dimension Schematics
The Forerunner® 645 Music drawn to scale — from above, and in profile against the wrist.
- Garmin Forerunner® 645 Music42.5mm · 13.5mm thick
3D preview
Garmin Forerunner® 645 Music on a wrist
On an arm sized to your own wrist — the view a product photo never gives you.
Shapes are built from published measurements, not manufacturer 3D models — accurate proportions, generic dial.
Forerunner® 645 Music battery life
The runtime the manufacturer publishes for everyday use.
- Smartwatch5 hours
How the Forerunner® 645 Music ranks on battery
Against the 260 Garmin watches in our database, ranked on each figure Garmin publishes.
- Everyday use7 days#205 of 249
- GPS tracking14 hours#190 of 235
Forerunner® 645 Music specifications
The figures that decide a purchase, followed by every line Garmin publishes.
- Battery life
- Smartwatch Mode: Up to 7 daysGPS mode without music: Up to 14 hoursGPS mode with music: Up to 5 hours
- Display
- 1.2" (30.4 mm) diameter
- Resolution
- 240 x 240 pixels
- Bezel
- Stainless steel
- Glass
- Corning® Gorilla® Glass 3
- Strap
- Silicone
- Storage
- 200 hours of activity data
Full specification sheet
141 published lines across 18 groups, unedited
Overview
- Family
- Garmin
General
- Battery life
- Smartwatch Mode: Up to 7 daysGPS mode without music: Up to 14 hoursGPS mode with music: Up to 5 hours
- Display Size
- 1.2" (30.4 mm) diameter
- Lens material
- Corning® Gorilla® Glass 3
- Bezel material
- Stainless steel
- Colour display
- Memory/history
- 200 hours of activity data
- Strap material
- Silicone
- Display Resolution
- 240 x 240 pixels
- Quick release bands
- Yes (20 mm, Industry standard)
Sensors
- GPS
- Compass
- GLONASS
- Galileo
- Gyroscope
- Thermometer
- Accelerometer
- Barometric altimeter
- Garmin Elevate™ wrist heart rate monitor
Product Info
- Main SKU
- 010-01863-30
- Product ID
- 612476
- Product Name
- Forerunner® 645 Music
- Release Date
- 1/9/2018
- Product Variation
- With Black Coloured Band
Clock features
- Timer
- Stopwatch
- Time/date
- Alarm clock
- GPS time sync
- Sunrise/sunset times
- Automatic daylight saving time
Cycling features
- Courses
- Race an activity
- Compatible with Varia™ lights
- Speed and cadence sensor support (w/sensor)
- Compatible with Varia™ radar (rear-facing radar)
- Compatible with Varia Vision™ (head-mounted display)
- Alerts (triggers alarm when you reach goals including time, distance, heart rate or calories)
Running features
- Run workouts
- Race predictor
- Foot pod capable
- Running dynamics
- Yes (with compatible accessory)
- Performance condition
- Stride length (real time)
- Yes (with compatible accessory)
- Vertical oscillation and ratio
- Yes (with compatible accessory)
- Ground contact time and balance
- Yes (with compatible accessory)
- GPS-based distance, time and pace
- Cadence (provides real-time number of steps per minute)
What You'll Love
- Garmin Pay™
- Training Status
Activity profiles
- Gym
- Strength Training, Cardio Training, Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing and Yoga
- Swim
- Pool Swimming
- Cycling
- Biking, Indoor Biking
- Outdoor recreation
- Skiing, Snowboarding, XC Skiing, Stand up Paddleboarding, Rowing
Swimming features
- Countdown start
- Pool swim workouts
- Drill logging (pool swim only)
- "Repeat on" rest timer (pool swim only)
- Basic rest timer (up from 0) (pool swim only)
- Stroke type detection (freestyle, backstroke, breaststroke, butterfly) (pool swim only)
- Pool swim metrics (lengths, distance, pace, stroke count, swim efficiency (SWOLF), calories)
Outdoor recreation
- TracBack®
- Back to start
- UltraTrac mode
- Vertical speed
- GPS coordinates
- Elevation profile
- Total ascent/descent
- Distance to destination
- Point-to-point navigation
- Breadcrumb trail in real time
Daily smart features
- Calendar
- Connectivity
- Bluetooth®, ANT+®, Wi-Fi®
- Find my phone
- Find my watch
- Weather forecasts
- Smart Notifications
- VIRB® camera remote
- Smartphone compatibility
- iPhone® and Android™
- Controls smartphone music
- Plays and controls watch music
- Compatible with Garmin Connect™ Mobile
- Text response/reject phone call with text (Android™ only)
- Connect IQ™ (downloadable watch faces, data fields, widgets and apps)
Activity tracking features
- TrueUp™
- Move IQ™
- Step counter
- Floors climbed
- Calories Burned
- Intensity minutes
- Distance travelled
- Automatic rep counting
- Garmin Connect™ Challenges app
- Yes (optional Connect IQ app)
- Auto goal (learns your activity level and assigns a daily step goal)
- Move alerts (displays on device after a period of inactivity; walk for a couple of minutes to reset it)
Workout and Training Plans
- Cardio workouts
- Strength workouts
Health & Wellness Monitoring
- Sleep
- Yes (Advanced)
- Hydration
- Yes (in Garmin Connect™ and optional Connect IQ™ widget)
- Fitness Age
- Yes (in app)
- All-day Stress
- Women's Health
- Yes (in Garmin Connect™ and optional Connect IQ™ widget)
- Resting heart rate
- Relaxation Breathing Timer
- Wrist-based heart rate (constant, every second)
Safety and tracking features
- Incident Detection during select activities
Kid activity tracking features
- Toe-to-Toe™ Challenges app
- Yes (optional Connect IQ Toe-to-Toe™ Challenges app)
Training, planning and analysis features
- % HRR
- % HR Max
- HR Zones
- HR Alerts
- Auto Lap®
- Manual lap
- Auto Max HR
- Auto scroll
- Finish time
- HR Calories
- Voice alerts
- Physio TrueUp
- Recovery Time
- Training Load
- VO2 Max (Run)
- Course guidance
- Training Effect
- Virtual partner
- Race an activity
- Advanced workouts
- Interval training
- Customisable alerts
- Garmin Live Segments
- Strava Live Segments
- Customisable screen(s)
- GPS speed and distance
- Configurable lap alerts
- Touch and/or button lock
- Activity history on watch
- Downloadable training plans
- Training Effect (Anaerobic)
- Customisable activity profiles
- Auto Pause® automatic timer halt
- HR Broadcast (broadcasts HR data over ANT+® to paired devices)
Alternatives to the Forerunner® 645 Music
Watches that cover a similar amount of wrist, with the measurements that separate them.
Garmin
Forerunner® 645
- Width
- 42.5mm
- Thick
- 13.5mm
- Weight
- 41.8g
Garmin
Forerunner 170
- Width
- 42.6mm
- Thick
- 11.9mm
- Weight
- 41g
Garmin
Forerunner 170 Music
- Width
- 42.6mm
- Thick
- 11.9mm
- Weight
- 41g
Garmin
Forerunner 70
- Width
- 42.6mm
- Thick
- 11.9mm
- Weight
- 40g
Garmin
Forerunner 570 - 42mm
- Width
- 42.4mm
- Thick
- 12.9mm
- Weight
- 42g
Garmin
Forerunner® 245
- Width
- 42.3mm
- Thick
- 12.2mm
- Weight
- 38.5g
Forerunner® 645 Music — Frequently Asked Questions
Will the Garmin Forerunner® 645 Music fit my wrist?
The Garmin Forerunner® 645 Music looks balanced on flat wrist widths of roughly 45–61mm (about 12.0–16.3cm circumference). Drag the slider above to check it against your own measurement.
How long does the Garmin Forerunner® 645 Music battery last?
Garmin rates it at 5 hours per charge in everyday use.
How does the Garmin Forerunner® 645 Music battery compare with other Garmin watches?
At 7 days in everyday use it ranks #205 of the 249 Garmin watches in our database — below the middle of the range. The full ranking, including GPS and power-saving figures, is on our Garmin battery life comparison.
Is the Garmin Forerunner® 645 Music thick for a 43mm watch?
At 13.5mm, thicker than 68% of 43mm watches — it will sit noticeably high on the wrist. Thickness, not case width, is what decides whether a watch catches on a shirt cuff.
What other watches are the same size as the Garmin Forerunner® 645 Music?
OnePlus Watch 3 43mm, Oppo Watch X2 Mini, Omega Speedmaster Moonphase Stainless Steel / Black Meteorite / Bracelet, Zenith Defy Extreme Diver Shadow / Bracelet all sit within half a millimetre of the Garmin Forerunner® 645 Music's 42.5mm case, so they cover the same amount of wrist.
