Garmin Forerunner 245 vs Forerunner 645 – key differences

Key differences Forerunner 245 vs Forerunner 645:

Since the announcement of the Garmin Forerunner 245. Users have been asking, what are the key differences between the Forerunner 245 vs Forerunner 645.

While the differences are small between both Garmin wearables, it is worth knowing the fundamental differences If you going to part with your hard earned cash; you want to make sure it is the right running watch for you.

Garmin Forerunner 245 vs Forerunner 645: DesignGarmin forerunner 245 vs Forerunner 645 firstbeat

The Forerunner 645 colours are;

  • Stainless steel and black band – Music only
  • Stainless steel with Cerise band – Music only
  • Slate grey with a black band – Music only
  • Rose gold with a black band – Music only
  • Stainless steel with sandstone band – Non-music

When looking at the Forerunner 645 vs Forerunner 245 in terms of design, it all comes down to personal taste.

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Forerunner 245 vs Forerunner 645 feature differencesGarmin forerunner 245 vs Forerunner 645 design

So at a high-level, I have broken them down into three areas, fitness, Firstbeat, smart and battery.

Garmin Forerunner 645 key features

  • Fitness
    • Barometric altimeter
    • Garmin Running Power
    • More data fields
    • Tracks 19 sports profiles.
  • Firstbeat
    • 11 Firstbeat features
      • Lactate Threshold
  • Smart
    • Garmin Pay contactless payments
    • Both Forerunner 645 variants have WiFi
    • Group track
    • Strava live segments
  • Battery
    • Smartwatch Mode: Up to 7 days,
    • GPS mode with music: Up to 5 hours
    • GPS mode without music Up to 14 hours

Garmin Forerunner 245 key features

  • Fitness
    • Pulse OX sensor along with new ELEVATE HR sensor
    • Tracks 16 sports profiles
  • Firstbeat
    • 11 Firstbeat features
      • Race Time Predictor
      • Body resources
  • Smart
    • Crash detection
  • Battery
    • Smartwatch Mode is up to 7 days
    • GPS mode with music is up to 6 hours
    • GPS mode without music is up to 24 hours

As comments have pointed out below, the Forerunner 645 has “race time predictor” However it’s not the same as found on the FR245 using Firstbeat.

Garmin Forerunner 245 vs Forerunner 645: fitnessGarmin forerunner 245 vs Forerunner 645 firstbeat

In terms of the fitness features, both Forerunner models are not so different in terms of sports tracking. However, the Forerunner 645 track’s a few more sports.

Garmin Forerunner 645 sports profiles

Running, Treadmill Running, Indoor Track, Strength Training, Cardio Training, Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing, Yoga, Skiing, Snowboarding, XC Skiing, Stand up Paddle boarding, Rowing, Biking, Indoor Biking, Pool Swimming and other

Garmin Forerunner 245 sports profiles

Outdoor run, Treadmill, Indoor Track, Bike outdoors, Pool Swim, Trail Run, Bike Indoors, Row Indoors, Walk outdoors, Walk Indoors, Strength, Cardio, Yoga, Elliptical, Stair Stepper, Other

The Forerunner 645 comes with barometric altimeter which should give you far more accurate elevation readings, and stairs climbed.

You also get Garmin running power when you connect a compatible accessory. The final difference is the ability to have more data fields during workouts.

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Another standout feature on the Forerunner 245 is the inclusion of Garmin’s new ELEVATE HR sensor with Pulse OX that features on the Forerunner 945.

Garmin Forerunner 245 vs Forerunner 645: FirstBeat

Turning to Firstbeat features. The Forerunner 245 has 11 features compared to the Forerunner 645’s 11. But

  • VO2max Fitness Level – Forerunner 245 and 645
  • Lactate Threshold – Forerunner 245 and 645
  • Training Effect: Aerobic – Forerunner 245 and 645
  • Training Effect: Anaerobic – Forerunner 245 and 645
  • Real-Time Performance Condition – Forerunner 245 and 645
  • Calories Burned – Forerunner 245 and 645
  • Training Load – Forerunner 245 and 645
  • Training Status – Forerunner 245 and 645
  • Quick Stress Level Test – Forerunner 245 and 645
  • All-day Stress & Recovery – Forerunner 245 and 645
  • Recovery Time Advisor – Forerunner 245 and 645
  • Lactate Threshold – Forerunner 645 Only
  • Body Resources – Forerunner 245 only
  • Race Time Predictor – Forerunner 245 only

Again, while the Forerunner 245 vs Forerunner 645 share similar Firstbeat features. The feature slit could prove vital to you

Body Resource – Forerunner 245

Garmin calls this feature body battery and takes the physical activity, stress, and recovery data and combines it. You then get a Body battery score to enable you to make better, more informed decisions based on your physical condition.

Race Time Predictor – Forerunner 245

They design the race Race Time Predictor to give you a head’s up on how long it will take you to complete several popular race distances. Distances include 5k, 10k, half-marathon and marathon.

Lactate Threshold – Forerunner 645

This data can be gathered during a guided test specifically designed to record the data needed to detect your Lactate Threshold, or it can be calculated from normal running activities that include enough quality heartbeat data from each zone.

Garmin Forerunner 245 vs Forerunner 645: smart featuresGarmin forerunner 245 vs Forerunner 645 smart

The smart features on both Forerunner watches are similar for things like call, text and app alerts. However, they have key differences that could swing it either way for you.

Garmin Forerunner 645 smarts

The Forerunner 645 has Garmin pay, and while adoption is still slow in some parts of the world. If you opt for this watch, you could use it to make payments on from your wrist contactless.

You also get Group track and Strava live segments with the Forerunner 645. These features are useful for group events or competing on Strava with your friends.

Garmin Forerunner 245 smarts

Garmin has included safety and tracking features on the Forerunner 245.

This feature makes it easy to share your location with chosen contacts in case you need help. You can do this manually, or automatically with built-in incident detection.

Garmin Forerunner 245 vs Forerunner 645: battery lifeGarmin forerunner 645 vs Forerunner 245 battery life

As with sports watch, battery life is essential, and both offer impressive battery performance.

The Forerunner 645 offers battery performance of;

  • Smartwatch Mode: Up to 7 days,
  • GPS mode with music: Up to 5 hours
  • GPS mode without music Up to 14 hours

The Forerunner 245 offers battery performance of;

  • Smartwatch Mode is up to 7 days
  • GPS mode with music is up to 6 hours
  • GPS mode without music is up to 24 hours

Something else that is worth pointing out, Garmin says battery life will deplete quicker when using the Pulse Ox sensor for sleep tracking on the Forerunner 245

Garmin Forerunner 245 vs Forerunner 645: Price

Starting with the Forerunner 645, which begins at £349/$399 non-music,  up to £399/$449 for the music version.

Then the Forerunner 245 starts at £249/$299 non-music,  up to £299/$349 for the music version.

Garmin Forerunner 245 vs Forerunner 645: Which one?

My honest view on this is, it all comes down to individual preference and the features you want. While both Forerunner 245 vs Forerunner 645 offer similar features,  you need to take into account the key elements that will make a difference to you.

If it were me spending my money, then I would go for the FOrerunner 245 because I don’t use Garmin Pay and the extra features on the 245 win it for me.

Why Buy a Forerunner 645?Why buy the Forerunner 645 vs Forerunner 245

The forerunner 645 offers several reasons to buy from a fitness perspective with Running power support, Barometric altimeter or the Strava live segments.
If the fitness features are not tempting enough, then you also have Garmin Pay for making payments from your wrist, contactless.
You also get more sports profiles to choose from along with the ability to have more data fields.
Buy the Forerunner 645 from Wiggle
Why buy a Forerunner 245?Why buy the Forerunner 245 vs Forerunner 645

Turning to the Forerunner 245 which offers some impressive features from the new ELEVATE HR sensor with Pulse OX. You also get UltraTrac mode which will extend battery life

You also get more Firstbeat features with the Forerunner 245 over the Forerunner 645. So if you need these extra features, then this watch could be the right choice.

If safety is important to you, then the incident detection is there when you need to alert someone of an emergency.

Buy the Forerunner 245 from Wiggle

So that’s a wrap, and I hope this Forerunner 245 vs Forerunner 645 comparison was useful. If you have questions or a comment, please them below and subscribe to receive a notification when the full reviews land.

Editors note – we have updated the article to reflect changes via firmware updates

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19 COMMENTS

  1. Is not clear you article , which is better.
    From my perspective 245 because:
    Body Resources
    Respiration Rate
    Race Time Predictor

    • I don’t think it’s right for me to say which is best. It’s all down to the user to make a decision on what features are right for them

      • Hi. My FR645 has always have a Race Time Predictor based on the VO2max it detected. Is the FR245 RTP any different?

        • Your cardiorespiratory fitness level (VO2max) offers good insight into your ability to maintain a certain level of performance over a period of time. VO2max provides a strong basis for predicting how you will perform in in an endurance event, but your VO2max isn’t the only thing that matters. The work you do to prepare should be considered too.

          To improve the reliability of your predicted finish times, Firstbeat takes a number of additional considerations into account. These include long- and short-term trends in your weekly running mileage totals. Similarly, Training Load trends are factored into the analysis, along with specific details like how longer runs contributed to your overall load.

          Race Time Predictions are automatically updated as your situation changes.

  2. I have the 645M and it does have race predictor and Ultratrac.

    I don’t see incident tracking and I have 5.2 firmware.

  3. I’m running with a Garmin 230 and want to upgrade to get music and the wrist based heart monitor. I don’t carry my phone when I run. With both the 245 and 645 music available at the same price in the UK I’m stumped on which one to go for. I like the idea of Garmin Pay but as far as I can see my bank, First Direct, doesn’t currently support it. I recreationally run half marathons with the odd full thrown in. I wear I regular watch normally so only wear my Garmin to run and don’t bother with smart notifications. Decisions, decisions…

    • Like you, I am with First Direct and I can confirm Garmin Pay is not supported.

      I also saw that the other day the 645 is the same price, I think the link at the bottom of this article takes you to wiggle with it at that price.

      I suppose it’s all down to personal choice. I have a Fenix 5x Plus and a Apple Watch as my everyday watches and I still use my phone for contactless payments via Apple Pay.

      If you only use the Garmin to run then very little point in getting a watch for Garmin Pay

  4. FirstBeat have confirmed to me today that Respiratory Rate is not on the new 245, has been removed on the website as well. Was a listing error, so 245 just has the 2 extra FirstBeat metrics.

    Just an FYI.

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Jon Ratcliffe
I have a huge passion for technology having worked in the sector for over 18 years in a variety of roles. I cover Wearables, tech and smart home. My reviews and information will talk about how the product works in reality and not just what the marketing departments want you to think.

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