▷ Garmin Forerunner 645 Specs | Detailed Comparison To 735XT and 935

The Garmin Forerunner 645 is listed on Garmin’s website with the detailed specs BELOW.

Garmin Forerunner 645 Review MusicThe specifications are broadly ‘as expected’ several weeks ago.

A formal Garmin announcement is not now likely until around the time of CES2018.

This looks to me like the basic physical hardware of the Vivoactive 3 (with more buttons and no touch screen 😉 ) but also most tasty features of the Fenix 5/Forerunner 935 thrown in; perhaps warranting an upgrade from your Forerunner 630?

I’ll summarise the important differences and then you can read throught the detailed specs and comparisons, further below


  • It looks to have everything a running watch could ever ‘need’.
  • The bits of functionality it ‘misses’ out on are not core to running.
  • Personally I would prefer a sports watch appearance, but Garmin have probably made the right call with this design for the broad target market of runners
  • It’s expensive BUT the onboard MUSIC could make this a ‘Kerching moment’ for Garmin’s accountants.
  • The Forerunner 645 is clearly different from other Garmins in the Forerunner range.

Garmin 645 Bible ⌚ Garmin 645 Review Forerunner Music


  • New format compared to style of the Forerunner 630 / 235…very similar 5 button format as Garmin 935
  • Strong glass and overall ‘lightweight’
  • Standard bands
  • Same screen resolution as the Fenix 5/935 at 240x240px
  • Battery life looks low.
  • Lots of connectivity – probably every key function
  • Music with c800 onboard songs and BLE headphone connectivity
  • Garmin Pay (contactless effectively won’t be widely avaialble until 2018)
  • It’s a cycling watch BUT it will NOT support your power meter
  • It’s a pool swim watch BUT will not cache underwater HR from HRM-TRI. Not really designed for open water use with restricted functionality there.
  • It’s not a triathlon watch ie it does not have multi-sport profiles
  • It has no golf abilities
  • It has more limited hiking-type functionalities compared to the 935./Fenix 5
  • It has all the activity tracking functionality.
  • Supports both BLE and ANT+ sensors
  • Has almost all the clever Firstbeat physiological functionality
  • ‘Obviously’ it will support Garmin’s Running Power.


Best REI/Wiggle/PMC price is linked to. Prices approx $400-$450 or £480-£520 and UNlikely for non-Music to fall below $400 in 2019.


Garmin Forerunner 645 MusicGarmin Forerunner 735XTGarmin Forerunner 935
Top-end running WatchTri-Lite WatchSuper Tri Watch
Headline RRP USA$450$350$500
Lens MaterialCorning® Gorilla® Glass 3chemically strengthened glasschemically strengthened glass
Bezel Materialstainless steelfiber-reinforced polymer
Case materialfiber-reinforced polymer
QuickFit™ watch band compatibleyes (22 mm)
Quick Release Bandsyes (20 mm, Industry standard)
Strap materialsiliconesiliconesilicone
Physical size42.5 x 42.5 x 13.5 mm44.5 x 44.5 x 11.9 mm47 x 47 x 13.9 mm
Weight42.2 g40.2 g49 g
Water rating5 ATM5 ATM5 ATM
Display typesunlight-visible, transflective memory-in-pixel (MIP)sunlight-visible, transflective memory-in-pixel (MIP)sunlight-visible, transflective memory-in-pixel (MIP)
Display size1.2″ (30.4 mm) diameter1.23″ (31.1 mm) diameter1.2″ (30.4 mm) diameter
Display resolution240 x 240 pixels215 x 180 pixels240 x 240 pixels
Color display Yes  Yes  Yes
Battery lifeSmartwatch Mode: Up to 7 daysSmartwatch Mode: Up to 11 daysSmartwatch Mode: Up to 2 weeks
GPS mode with music: Up to 5 hoursGPS mode: Up to 14 hoursGPS/HR mode: Up to 24 hours
UltraTrac™ mode: Up to 24 hours without wrist heart rateUltraTrac™ mode: Up to 60 hours without wrist heart rate
Memory/History200 hours of activity data80 hours of activity data64 MB
Clock Features
GPS Time SyncYesYesYes
Automatic daylight saving timeYesYesYes
Alarm clockYesYesYes
Sunrise/sunset timesYesYesYes
Face It™ watch face creatorYesYesYes
Garmin Elevate™ wrist heart rate monitorYesYesYes
Barometric altimeterYesNoYes
Daily Smart Features
ConnectivityBluetooth®, ANT+®, Wi-Fi®YesBluetooth® Smart, ANT+®, Wi-Fi®
Connect IQ™ (downloadable watch faces, data fields, widgets and apps)YesYesYes
Smart notificationsYesYesYes
Text response/reject phone call with text (Android™ only)YesNoNo
Music controlsYesYesYes
Plays Onboard MusicYesNoNo
Music Storageup to 800 songsNoNo
Find My PhoneYesYesYes
Find My WatchYesYesYes
VIRB® remoteYesYesYes
Smartphone compatibilityiPhone® and Android™YesiPhone®, Android™, Windows®
Compatible with Garmin Connect™ MobileYesYesYes
Garmin Pay™YesNoNo
Activity Tracking Features
Step counterYesYesYes
Move bar (displays on device after a period of inactivity; walk for a couple of minutes to reset it)YesYesYes
Auto goal (learns your activity level and assigns a daily step goal)YesYesYes
Sleep monitoring (monitors total sleep and periods of movement or restful sleep)YesYesYes
Calories burnedYesYesYes
Floors climbedYesYesYes
Distance traveledYesYesYes
Intensity minutesYesYesYes
Move IQ™YesNoYes
Fitness Ageyes (in app)Noyes (in app)
Fitness Equipment/Gym
Preloaded gym activity profilesStrength Training, Cardio Training, Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing and YogaIndoor Rowing, Strength Training and Cardio Training
Cardio workoutsYesYes
Strength workoutsYesYes
Automatic rep countingYesYes
Training, Planning and Analysis Features
GPS speed and distanceYesYesYes
Customizable data pagesYesYesYes
Customizable activity profilesYesYesYes
Auto Pause®YesYesYes
Advanced workoutsYesYesYes
Downloadable training plansYesYesYes
Auto Lap®YesYesYes
Manual lapYesYesYes
Virtual PartnerYesYesYes
Configurable lap alertsYesYesYes
V02 maxYesYesYes
Training Status (lets you see if you’re training effectively by tracking your training history and fitness level trend.)YesNoYes
Training Load (your total training load for the last 7 days calculated from estimated EPOC)YesNoYes
Training Effect (aerobic)YesYesYes
Training Effect (anaerobic)YesNoYes
Customizable alertsYesYesYes
Audio promptsYesYesYes
Finish timeYesYesYes
Race an ActivityYesYesYes
Auto multisport activitiesYesYesYes
Manual multisport activitiesYesYesYes
Course guidanceYesYesYes
Segments (Live, Garmin)YesYesYes
Strava features (Beacon, live segments)YesYesYes
Group LiveTrackYesNoYes
Touch and/or button lockYesYesYes
Hot keysNoNoYes
Auto scrollYesYesYes
Activity history on watchYesYesYes
Heart Rate Features
HR zonesYesYesYes
HR alertsYesYesYes
HR caloriesYesYesYes
% HR maxYesYesYes
% HRRYesYesYes
Recovery timeYesYesYes
Auto max HRYesYesYes
HRV stress test (measures your heart rate variability while standing still, for 3 minutes, to provide you with an estimated stress level; the scale of this is 1 to 100; low scores indicate lower stress levels)yes (with compatible accessory)yes (with compatible accessory)yes (with compatible accessory)
Records heart rate while swimmingNoyes (with HRM-Tri™ or HRM-Swim™)yes (with HRM-Tri™ and HRM-Swim™)
HR Broadcast (broadcasts HR data over ANT+™ to paired devices)YesYesYes
Running Features
Preloaded run profilesRunning, Treadmill Running, Indoor TrackyesRunning, Indoor Running, Trail Running
GPS-based distance, time and paceYesYesYes
Running dynamics (with accessory)YesYesYes
Vertical oscillation and ratio with accessory)YesYesYes
Ground contact time and balance (with accessory)YesYesYes
Stride length with accessory)YesYesYes
Performance conditionYesYesYes
Lactate threshold (with accessory)YesYesYes
Run workoutsYesYesYes
Race predictorYesYesYes
Foot pod capableYesYesYes
Outdoor Recreation Features
Preloaded outdoor recreation profilesSkiing, Snowboarding, XC Skiing, Stand up Paddleboarding, RowingHiking, Climbing, Skiing, Snowboarding, XC Skiing, Stand Up Paddleboarding, Rowing, Jumpmaster, Tactical
Point-to-point navigationYesYesYes
Bread crumb trail in real timeYesYesYes
Back to startYesYesYes
UltraTrac modeYesNoYes
Elevation profileYesNoYes
Distance to destinationYesYesYes
Barometric trend indicatorNoNoYes
Storm alertNoNoYes
Trail run auto climbNoNoYes
Vertical speedYesNoYes
Total ascent/descentYesNoYes
Compatible with BaseCamp™YesNoYes
GPS coordinatesYesYesYes
Projected waypointNoNoYes
Sight ‘N GoNoNoYes
Area calculationNoNoyes (via Connect IQ™)
Hunt/fish calendarNoNoyes (via Connect IQ™)
Sun and moon informationNoNoyes (via Connect IQ™)
Dual grid coordinatesNoNoYes
Cycling Features
Preloaded cycling profilesBiking, Indoor BikingyesBiking, Indoor Biking, Mountain Biking
Bike lap and lap maximum power (with power sensor)No PowerYesYes
Race an activityYesYesYes
Time/distance alerts (triggers alarm when you reach goal)YesYesYes
Interval trainingYesYesYes
FTP (with accessory)NoYesYes
Compatible with Vector™ (power meter)No Cycling PowerYesYes
Power meter compatible (displays power data from compatible third-party ANT+™-enabled power meters)No Cycling PowerYesYes
Compatible with Varia Vision™ (head-mounted display)YesYesYes
Compatible with Varia™ radar (rear-facing radar)YesYesYes
Compatible with Varia™ lightsYesYesYes
Speed and cadence sensor support (with sensor)yes (ANT+® and Bluetooth® Smart)ANT+ Onlyyes (ANT+® and Bluetooth® Smart sensors)
Swimming Features
Preloaded swim profilesPool SwimmingPool Swimming, Open Water SwimmingPool Swimming, Open Water Swimming
Pool swim metrics (lengths, distance, pace, stroke count/rate, calories)YesYesYes
Stroke type detection (freestyle, backstroke, breaststroke, butterfly)YesYesYes
Swim efficiency (SWOLF)YesYesYes
Drill loggingYesYesYes
Pool swim workoutsYesYesYes
Open-water swim metrics (distance, pace, stroke count/rate, stroke distance, calories)NoYesYes
Heart rate (real-time during rests, interval and session stats during rests, and automatic heart rate download post-swim)Noyes (with HRM-Tri™ and HRM-Swim™)yes (with HRM-Tri™ and HRM-Swim™)


Fly In The Ointment


The 645 is super exciting. However my worry is that it looks a bit too much like the Vivoactive 3. And maybe it is a bit too much like the Vivoactive 3. If so this could be a Houston moment…I hope not.

Read this to see what I mean:

Garmin Vivoactive 3 Review – Detailed | Apple Watch Competitor


If you are keen for the most tech awesome running watch right now then it would have to be the Garmin 935 (reviewed here) but, be warned, that the 645 has music and Garmin Pay


Best REI/Wiggle/PMC price is linked to. Prices approx $400-$450 or £480-£520 and UNlikely for non-Music to fall below $400 in 2019.

Reader-Powered Content

This content is not sponsored. It’s mostly me behind the labour of love which is this site and I appreciate everyone who follows, subscribes or Buys Me A Coffee ❤️ Alternatively please buy the reviewed product from my partners. Thank you! FTC: Affiliate Disclosure: Links pay commission. As an Amazon Associate, I earn from qualifying purchases.

65 thoughts on “▷ Garmin Forerunner 645 Specs | Detailed Comparison To 735XT and 935

      1. Says iHeart Radio. You can download for offline play.

        “iHeartRadio: All Your Favorite Music. All our Favorite Stations

        iHeartRadio has unlimited music and thousands of radio stations all in one app. Sign up for a free trial of iHeartRadio All Access today to take your favorite radio stations, music, news, podcasts, sports, talk and comedy shows offline while you run. Get your 30-day trial here.”

      2. I saw the mention of iHeartRadio, though I’d be very disappointed if that’s the only streaming service that can sync with the 645. If that’s indeed the case, I’d personally wait until other services are offered or perhaps pass entirely on the 645.

  1. Great,that’s my present sorted out, delighted they have dropped the touchscreen was one of the main reasons i returned my 630 previously and got a 235 instead. The silver ring out the outside looks a bit like the 405 touchring, hope they are not bringing that back.

    1. it’s not 100% yet but that’s how it looks to me.
      we need to just check it’s a bit better than the VA3 before we let you spend your hard-earned cash tho 😉 Please keep Mr Visa at bay for now 🙂

      1. May I ask why you don’t like a touchscreen ? I own a 620 and I am so used to touch the screen when I want to switch between data fields. To me, it seems easier when running. I didn’t buy the 935 almost only because of this but maybe I’m wrong.

  2. As a 935 owner I won’t be changing but if I was buying from scratch today then it would be a contender. I’m mostly a runner these days, I do cycle but don’t use a power meter and I don’t swim in any meaningful way. The music feature is something that I want badly but I have fears about how usable the Garmin interface will be (both in terms of getting music onto the device and playing it on the move – I only actually want basic shuffle all functionality while running). And then comes along the big dealbreaker for me (if correct), battery life. Goodbye to charging once a week or less as with my 935. I’ve done the daily (or every other day) charging with an Apple Watch and don’t want to go back to that. Same old Garmin really. I know they need to give a reason for people to buy the expensive devices, but with 5 hour GPS I’d be marginal for completing a marathon before my watch died (I said I run, I didn’t say i was fast!!!). In short, if I was buying then I’d choose the 935 again and continue with my iPod shuffle for a while longer

  3. Wow, that thing is DoA. Other than on-board music (the first in an obvious trend of watches to come with music storage) it doesn’t fit ANY niche at all. biking with no power, swimming with no HR cache, no triathlon…and just 50 bucks cheaper than the vastly superior 935, which is going have a price drop around the launch of the 645…

    I’m sorry for the incoming Hyperbole…but the watch is a Frankenstein monstrosity of a device. It’s almost like Garmin was milling around in their workshop and took all the odds and ends from every other watch they made in the last year, took a bit of glue and duct tape and “VIOLA!”

    You have the 645.

    1. It’s as bad as all the other gimmicks at these crazy prices. At least we should praise the fact that is targeted at the disappearing niche of (semi) serious runners and not at the general group of fitness users with disposable income in their pockets who because they wear lycra and sport a $500 watch they see themselves as athletes… LOL

      1. hey that’s me you’re describing there 😉
        but yes, i agree with your sentiment.
        my concern is kind of related in that if it’s like the VA3 then it’s not really a sports watch but rather a 247 watch with gret runnign features. the music WILL be really appealing to LOTS of people…probably this products saving grace.

  4. The new 645 watch is not on Garmin’s website anymore. As a runner only, it looks like it has more than I need and all there can be today in a GPS watch. The music and the stronger glass are a big plus and the smaller size will be much better for my small wrist.

      1. For runners only this would be a great high-end watch (even at $450) if the battery life is better than listed above. We’ll see. For me (primarily a runner who wants daily activity tracking and notifications), recharging more than once a week doesn’t differentiate much from alternatives (i.e., 935). Perhaps that’s their plan!

      2. Battery life for TomTom Runner3 is 5 hours with GPS+HR+music, while 9 hours for GPS+HR only. If that’s the same for the FR645, then it’s acceptable, but far from good for a 450 EUR watch .

      3. good point MArc, I was going to double check that same comparison myself.
        so we could probably still see 8-11 hours for the 645 in non-music mode.
        put the gps in ‘worst’ mode
        add a decent footpod
        use a hrm

        and then maybe its even more.

  5. Good timing, a fall at a hill running event at the w/end has left my 620 with a big scrape across its face (& me with a few stitches on my forehead!) so think I know what my xmas present to myself will be 🙂

  6. The big plus it seems is they have finally added a baro altimeter to their top running watch which is a huge plus. To people running up and down a lot that’s very nice also not having to rely to altitude adjustments on the websites. Touch screen on the 630 was good with some head scratchy features (like you cant just block the screen and not the buttons) – could have left it with improvements. Music check… Optical Heart Rate… serious runners will still use chest straps for sessions that matter

  7. I’ve been waiting since june for this release to finally decide which Garmin watch to buy.
    The 935 feels overkill since since I’m predominantly a runner (albeit slowish) but the features listed don’t fully convince.

    Guess I’ll wait for your in-depth review and comparison (wink-wink) before the final decision.

  8. Why is this music feature so desired? You lose battery life and your phone will do it better. Are you not going to carry a phone then when you run? Also, any update on a successor to the 235? I was hoping the 245 would be out by now…Thanks!

    1. personally i run with music 0.01% of the time. but i see a LOT of people running with music. say 50%.

      245..nope nothng. it’s one of those ‘obivous’ things that will happen. obvious apart from the timing. but it will be no later than q1.2018 i reckon

      1. Right I am not saying people don’t run with music – but why would you want a dumbed down version of music on your watch when you have your phone that has everything? Do people not carry a phone when they run? Bah – I was holding out for a running watch instead of buying the 235. The 935 seems like overkill for me and this 645 has music which I don’t want/need. Do you have any info on what the 245 would have? Thanks!

      2. saves 2 devices. garmin will have done market research.
        when i have to carry a smartphoen to handle some bizarre sensor it is a real PITA..i really dont like carrying a phone.
        why dumbed down? quality will be the same if you think about it
        you are a 245 man i reckon

      3. Yes just don’t want to sacrifice battery for music. But in any case, do you have any info on what to expect from the 245?

      4. no info. but look at the other post compareing 235/630 and 645 and then you can extrapolate what will be taken out of the 645 to make the 245. I might do that as a post but I am running out of time as I have to make a honest living elsewhere!!

    2. I run with music about 95% of the time, so a watch with music storage does appeal to me. I currently carry a phone for the sole purpose of music, it would be nice to carry one fewer device. It’s likely that I fit squarely into the “semi-serious runner” market segment that Garmin is targeting with the 645.

    3. Call me crazy but I do not want to carry a 6 inch phone with case and a magnetic plate under the case(for easier hookup in the car) every time I run. I just want to run free…but with music. 😉

    4. I assume most people would prefer to run without a phone if possible. I do. What this is missing is some sort of LTE capability for emergency access, like the Apple Watch. Otherwise, it’d be a home run.

    1. 90% chance i’d say
      OR garmin could rationalise that they have the price right for the 645 compared to the range and so no need to go to the expense of making, packaging and selling a another variant.

  9. if SANS music the battery is up in the 15 hour range, and the BARO gives a reasonable vert reading, I’ll be there. Otherwise, I’m hopping over to the Suunto Spartan range…

  10. You have ‘type-o’ in the title. 745XT… I wish I had… 🙂
    Nevertheless I think that 645 is watch I was looking for BUT… with so weak battery and for so much money I would again consider choosing 935 over 645. BUT (again 🙂 I bought 3 weeks ago with a big discount the 735XT run Bundle version for 320 Euros and the price performance ratio is the best what I could “squeeze” from it.

  11. is there any sportwatch that has voice guidance feature for running? such as what freeletics run app does? or pulsometer app which telling the HR reading periodically.. or strava which periodically inform current stats..

    am using Garmin VAHR currently.. not really a fan in listening music while running.. yet still carrying phone and BT headset for voice guidance feature..

  12. I use my 735 for 99% of my outdoor runs and cycling, and a VA3 for most everything else (strength, yoga, treadmill runs, activity tracking)

    I would really like to get back to a one watch solution and the 645 as described here would do that for me. Especially if there is a non-music version or with music disabled it can get “GPS on” battery life similar to the 735.

    The VA3 is an “almost there” device for me but I’m not a fan of the touchscreen interface, particularly with the strength training app, and the short-ish battery life for someone who does between 7 and 13 hours of GPS activities a week.

    I wore my 735 24/7 for most of 2017 so going with the 935 wouldn’t be a big problem but I do like the looks of the VA3 so a better, more full featured, running watch with the VA3’s looks would check all of the boxes in my wish list.

    1. still not sure if a non-music version will be available. i’d imagine either version are same on battery life comapred to when the MUSIC version is not playing music.
      agree with your interface comments

    2. Thanks for this post; I almost bought either watch (735xt/va3). The forerunner 645 slightly slimmer without music would be my wish. I just found my forerunner 101, but care not to wear.

      1. what do you mean the 645 is slipping? it looks like it is supposed to ship march 5. is a garmin 245 still 100% going to come out? And what would be the main difference between it and the 645 – would it be cheaper?

      2. i think it was planned earlier than 5march. (from memory)
        main differences? no-one knows for sure outside of Garmin’s channels. but likely: no high end functions and removal of one or two useful training features.
        yes for sure it will be cheaper eg 630 vs 235

      3. but my question is how do you know with 100% certainity that a 245 model is coming out? has Garmin confirmed it is?

      4. There has been no press release about a 245.
        When a press release is issued then the details are simultaneously released. THAT is the only confirmation we will get.
        FWIW: I would bet LOTS of money that there will be a cut down Forerunner 645 called “245” or similar. I am not a gambler.

      5. So a 245 then is just speculation…. and if the 245 is supposed to be a “stripped” down version of the 645, what would they price it at? Because the cheapest 645 (non music) is $399. The original retail price of the 235 was $329. To me it wouldn’t make sense for them to release anything over $300 for the 245 – otherwise you would just buy the 645 at $399. Right?

  13. Thanks for the details! I notice one mistake in the comparaison table: Forerunner 645 don’t have Hot Keys…

  14. Excellent post but I was wondering if you could write a litte more
    on this subject? I’d be very grateful if you could elaborate
    a little bit further. Cheers!

Comments are closed.