Garmin Forerunner 745 vs Forerunner 645 – Product Comparison

Garmin Forerunner 745 vs Forerunner 645 – Product Comparison

The Garmin Forerunner 645 is a good quality GPS watch built primarily for runners. It has built-in music storage a solid selection of sports features, advanced running dynamics and support for Garmin running power. 

The Forerunner 745 is a significant upgrade on the Forerunner 645. Support for open water swimming, triathlon tracking, and cycling power meters are massive upgrades, but the list doesn’t end there. The FR745 also has a pulse oximeter (to measure blood oxygen levels),personalized workout recommendations, and a better battery life. 

In essence, the Forerunner 745 can do everything that he Forerunner 645 can, plus a whole lot more. The only reason to truly consider the FR645 is price. 

Table of Contents

Key Similarities - Forerunner 645 vs Forerunner 745

Forerunner 745

Forerunner 645

GPS, GLONASS & GALILEO

24/7 Activity Tracking

Advanced Sleep Tracking

Wrist-based HRM

Optical HRM Under Water

Indoor + Outdoor Running

Indoor + Outdoor Cycling

Indoor + Outdoor Rowing

Pool Swimming

Advanced Running Dynamics

Garmin Running Power

3rd Party Running Power

Music Storage

Payments from Watch

Garmin Running Coach

Barometric Altimeter

Gyroscope + Accelerometer + Compass

Bluetooth, ANT+, Wi-Fi

Garmin Connect IQ

Safety/Incident Detection

Point-to-Point Navigation

Screen Resolution

240 x 240 pixels

240 x 240 pixels

Display Size

1.2" (30.4 mm) diameter

1.2" (30.4 mm) diameter

Waterproof Rating

5 ATM

5 ATM

Music Storage Capacity

Up to 500 Songs

Up to 500 Songs

Smartwatch Battery Life

Up to 7 Days

Up to 7 Days

Topographical Maps

Golf Mode

Key Differences - Forerunner 645 vs Forerunner 745

FR745

FR645

Dimensions

43.8 x 43.8 x 13.3 mm

42.5 x 42.5 x 13.5 mm

Lens Material

Corning® Gorilla® Glass DX

Corning® Gorilla® Glass 3

Weight

47 grams

42.2 grams

GPS Battery

Up to 16 Hours

Up to 14 Hours

GPS Battery with Music

Up to 6 Hours

Up to 5 Hours

UltraTrac GPS Battery

Up to 21 Hours

Triathlon Mode

Open Water Swimming

Pulse Oximeter

Body Battery Score

Respiration Rate

Garmin PacePro

Garmin ClimbPro

Heat + Altitude Acclimation

Training Load + Training Focus

Daily Workout Suggestions

Main Reasons To Choose The Forerunner 645

Garmin_Forerunner_645_Main_Reasons

1. It's cheaper, and you might be able to find it on special

There is only one reason to choose the Forerunner 645. That reason is price.

To be more specific, it only makes sense to go for the FR645 if you can find it on special, and you have no interest in triathlon tracking. However, if the FR645 isn’t being discounted, you can unlock a huge number of benefits by upgrading to the FR745. It can literally do everything that the FR645 can do, plus a whole lot more. 

On this point, it’s worth noting that you should be able to find the non-music version of the Forerunner 645 for at least $100 cheaper than the FR745. If you’re not planning to use the music features and you don’t do triathlons, you can make a strong case for the value premise of the non-music FR645.

Main Reasons To Choose The Forerunner 745

Forerunner 745 Reasons

1. Open Water Swimming + Triathlon Tracking

Open water swimming and triathlon tracking tend to go hand-in-hand. If you opt for the Forerunner 745, you can unlock both of these features. To switch between each triathlon discipline, you simply need to push one button on the FR745. 

2. Garmin PacePro + Garmin ClimbPro

Garmin PacePro: PacePro offers pace guidance for  to help you stay on track during training. When PacePro is applied to a course loaded to your watch, it analyzes elevation changes along the course to calculate a pace strategy. The strategy calculates when to increase or decrease your pace along the course for the best overall pace. 

Garmin ClimbPro: ClimbPro detects the climb sections of a cycling course. When ClimbPro is activated, you will be able to see: 

  • The number of the climb including total climbs for the course
  • The distance remaining in the climb (Dist. to Go)
  • The ascent remaining for the climb (Asc. Remain.)
  • A chart showing the profile of the climb
  • The total climb distance
  • The remaining distance to each climb (Dist. to) 
  • Average gradient for each climb  (Grade)
  • Length of each climb

3. Pulse Oximeter

This wrist-based sensor  in the FR745 monitors blood oxygen saturation levels to provide a clearer picture of how you’re sleeping or how you’re adjusting to altitude.

4. Body Battery Score

Garmin’s body batter score combines your training data, sleeping data and heart rate data into one overarching metric called Body Battery Score. 

Most new Garmin’s (any watch with Garmin’s V3 elevate heart rate monitor) have the Body Batter Feature built-in. Unfortunately the FR645 was released a few months before the V3 heart rate monitor became the default setup for new Garmin activity trackers. 

5. Better Cycling Features + Cycling Power Meter Compatibility

The Forerunner 745 is a better sports watch for cyclists specifically. You can access additional cycling modes, functional threshold power, and cycling power meter compatibility. The bullet points below highlight the difference between the FR645 and the FR745 in terms of cycling features. 

FR645 Cycling Features

  • Cycling Alerts
  • Cycling Courses
  • Outdoor Cycling
  • Indoor Cycling
  • Race an activity
  • Compatible with Varia Vision
  • Compatible with Varia Radar
  • Compatible with Varia Lights
  • Speed and Cadence Sensor Support

FR745 Cycling Features

  • Cycling Alerts
  • Cycling Courses
  • Outdoor Cycling
  • Indoor Cycling
  • Race an activity
  • Compatible with Varia Vision
  • Compatible with Varia Radar
  • Compatible with Varia Lights
  • Speed and Cadence Sensor Support
  • Mountain Trail Biking
  • Bike Lap And Lap Maximum Power
  • Functional Threshold Power (FTP)
  • Cycling Power Meter Compatible
  • Advanced Vector Support

Sports Modes Comparison

FR645 Sports Modes

  1. Strength Training
  2. Cardio Training
  3. Elliptical Training
  4. Stair Stepping
  5. Floor Climbing
  6. Indoor Rowing
  7. Yoga
  8. Running
  9. Treadmill Running
  10. Indoor Track Running
  11. Trail Running
  12. Skiing
  13. Snowboarding
  14. XC Skiing
  15. Stand Up Paddleboarding
  16. Rowing
  17. Cycling
  18. Indoor Cycling
  19. Pool Swimming
  20. Walking

FR745 Sports Modes

  1. Strength Training
  2. Cardio Training
  3. Elliptical Training
  4. Stair Stepping
  5. Floor Climbing
  6. Indoor Rowing
  7. Yoga
  8. Running
  9. Treadmill Running
  10. Indoor Track Running
  11. Trail Running
  12. Skiing
  13. Snowboarding
  14. XC Skiing
  15. Stand Up Paddleboarding
  16. Rowing
  17. Cycling
  18. Indoor Cycling
  19. Pool Swimming
  20. Walking
  21. Pilates
  22. Outdoor Track Running
  23. Virtual Running
  24. Kayaking
  25. Mountain Biking
  26. Open Water Swimming
  27. Swimrun
  28. Triathlon Tracking

Final Thoughts

When you look at the combination of features, sports modes and fitness technology, it’s pretty clear that the Forerunner 745 is the winner of this product battle. Nevertheless, if you’re still on the fence at this point, these final buying tips may help: 

Go for the Forerunner 645 if: 

  • You have no interest in triathlon tracking
  • You can find the FR645 on special 
  • Running is your primary sport

Go for the Forerunner 745 if: 

  • You want the better sports watch overall
  • You want Garmin’s latest technology like the pulse oximeter and body battery score
  • You’re passionate about cycling
  • You’re a triathlete

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