​Garmin Forerunner 235 review

We put Garmin's new running watch with heart rate monitoring through its paces

The Garmin Forerunner 235 is the company's latest running watch with wrist-based heart rate monitoring built in. Coming less than a year after the Forerunner 225, it may seem like a simple incremental update.

But under-the-hood, Garmin has made big changes, cutting out Mio's tried and tested heart rate sensor in favour of its own tech.

It's a big step and risky one. And if you've read our Garmin Vivosmart HR review you'll know that we found substantial issues with its optical technology. But has it fixed them for the Forerunner 235? You'll have to read on to find out.

Garmin Forerunner 235: Design

Visually, the Forerunner 235's design isn't any kind of departure from Garmin's range of running watches, but it's still a fine looking device. We tested the version with the teal strap, which looks superb, and we were perfectly happy wearing it out and about. Sure, it might look a little silly with a suit, but it's actually one of the least offensive specialist sports watches out there.

It's light, too. Weighing just 42g it's easy to strap on and forget about, and was a welcome relief from other Garmin sports watches, especially the ridiculous Fenix 3 that we tested it against. If there's a downside to the Forerunner's svelte weight it feels a tad plasticky and flimsy, but that shouldn't put anyone off buying.

The Forerunner 235 boasts a 1.23-inch colour LCD screen with a resolution of 215 x 180 pixels. It's not winning any awards for visual prowess, but it does the job of displaying the time (it's always on so works as a proper watch) and stats such as running distance, time and pace and heart rate zones, where it uses the colour screen to best effect.

The strap is rubber with plenty of holes for adjustment, but the strap can be a tad annoying. The loop that tucks in the excess strap can slip back towards the buckle, leaving you with a flappy bit of rubber, which needs some adjustment every time you put it on.

That's not the only irritating quirk of the design. The start run button is positioned towards the top left and we found it snagged when putting on jackets and coats, inadvertently starting exercise sessions, which we'd then have to manually discard. We're not sure why it's such an issue with the 235, as it's not something that we've found with any of Garmin's other Forerunners. Perhaps it's a symptom of mid-winter wear.

There's no built in memory so you can't add your own music to finally leave your smartphone at home, and that's still the biggest plus for the TomTom Spark.

Garmin Forerunner 235: Running metrics

Forerunner watches are complicated affairs these days – and that's certainly true for the Forerunner 235. Part fitness tracker with a smattering of smartwatch skills, there's a lot going on under the hood, but let's start the review with its strongest suit: sports tracking.

The Forerunner has four sport modes: running, running indoor (GPS turned off), bike and a catch-all free tracking setting.

It's quick to access the modes by pressing the main button on the top right, and you'll have to stand around for a bit while it gets a GPS lock. We're pleased to say that the Garmin Forerunner 235 was consistently lightning quick to get its GPS connection, and outperformed the Fenix 3, which often left us standing in the street getting cold before getting a lock.

The run tracking is extremely comprehensive, although falls short of the metrics captured by the flagship Garmin Forerunner 630. You get pace, distance, time and calories (of course) as well as average heart rate, max heart rate, cadence and Training Effect (TE) which rates how effective the session was for you out of five. It's a great line up of features that caters for everyone short of elite athletes. All the snazzy VO2 analysis is left to the bigger, badder Garmins, although recovery time recommendations do feature after workout sessions.

You can access most of these metrics mid-run and you can tap the up or down button to control the metrics shown on screen. Cycle right through and you'll get a big heart rate screen, with an arrow that displays your current zone. This is a fantastic addition, but we'll come onto its usefulness in the next section.

Another feature worth highlighting is the Forerunner 235's ability to load workouts synced from the Garmin Connect web app. In the tool you can build workouts, setting your desired warm up time, workout time, distance or intensity, and warm down period, and have it sent to the watch.

To load a session head to the main menu and on the watch and choose Workouts to load your training plan. The watch will guide you through, ensuring you warm up properly and stick to your goals.

It's a nifty system, but we have to say that the TomTom Spark boasts a load more interesting workout features straight from the watch. With no web set up required, you can load previous routes and ghost runs, racing your previous PBs with live details on the wrist. There's nothing like this in the Garmin ecosystem, and that's a real shame.

Garmin Forerunner 235: HR accuracy

With an optical sensor built into the Forerunner 235, the natural thing to question is whether it's finally possible to ditch the chest strap. We took it out for some detailed analysis against a chest strap and we can thoroughly conclude….drum roll please…no, it's not – for serious runners at least.

The data was slightly odd, and we found that the Forerunner 235's HR reading was very slow to get up to speed at the beginning of runs. Most sessions saw it lag 20-30bpm behind the Fenix 3 with a paired chest strap for the first five to ten minutes, before it caught up. So long as your pace remained steady, it would then stay fairly close to the strap reading.

However, if you then stopped and restarted, the Forerunner would take more time to calibrate to your heart rate once again.

The graphs below show the Garmin Forerunner 235 versus a Fenix 3 with chest strap on the same run.

For the most part the graphs follow each other closely but on both charts you can see an unnatural curve at the beginning of the run and after the rest period. This shows the lag that we described, although anecdotally from a number of runs with the two devices, it spent most of the run within five beats of the strap.

It's certainly not strong enough for tracking high intensity interval sessions (HIIT) or getting really granular with your sessions. We'd cautiously use it as a guide to our effort during long runs.

We don't have enough data yet to ascertain whether the Forerunner 235 is more or less accurate than the Forerunner 225, which uses Mio's technology rather than its own – but we're working on drilling down into that soon.

At this point it's worth taking a minute to process all this information. It's important to remember that you can pair a Garmin chest strap with the Forerunner 235, so you can still get the benefits of the device and accurate training tracking. But that means you're buying the Forerunner 235 for its 24/7 abilities – so if you're not interested that that aspect, pick a cheaper Garmin tracker such as the Forerunner 230.

And there's one more aspect to consider. If you want HR data to colour your workouts stats but can live without top accuracy then the Forerunner's HR data is good enough. Just don't rely on it.

Garmin Forerunner 235: Activity tracking

As well as hardcore run tracking, the Forerunner 235 is also designed to be used as a daily activity tracker. This isn't new ground for running watches – most Forerunners do it, as does the TomTom Spark. However, the Forerunner 235 really raises the bar, for a number of reasons.

Firstly, the design helps. By actually looking decent and not horrifically bulky, you might actually be tempted to wear the Forerunner 235 all-day, every day. Wearing it to bed may be a step too far, but it's possible. You could never say that about the TomTom Spark.

The next reason for its fitness tracking success is technological. Unlike the Spark or any of the other Forerunners, the 235 makes use of the optical HR sensor 24/7, and will keep a record of your heart rate throughout the day. Tap the down button and you'll be treated to a read out of your heart rate over the last 4 hours, with current and resting heart rate called out. It's easy to keep an eye on your stats – but our only complaint is that resting heart rate isn't called out within the app, and it can't be tracked over time.

Tap down again, and you'll get a breakdown of your steps, progress against the step goal, distance travelled in your day and calories burned.

That's not the summation of the activity tracking, and you'll see extra metrics in the Garmin Connect app. From there head to the Snapshots screen and swipe through to view active calories, sleep (and a summary of the last seven days), activities and weekly intensity minutes.

All-in-all the activity tracking is highly impressive and certainly one of the best we've seen from a dedicated running watch. The leader in this respect is the Fitbit Surge, which has the benefit of the company's expertise in activity tracking, but can't hold a candle to the Forerunner when it comes to real training.

Garmin Forerunner 235: Notifications

The Forerunner 235 is also capable of displaying notifications and calendar updates from a connected smartphone, meaning you can see calls, texts and other messages straight from the wrist.

While it doesn't offer any of the finesse or customisation options of a proper smartwatch, it's a simple yet effective system that ensures you're less likely to miss calls and saves you time reaching for your smartphone needlessly.

You only get the first line of a message or text, so it's hardly a proper smartwatch competitor, but works well enough.

If you press the down button and cycle past the fitness tracking screens you'll see a breakdown of your day's calendar appointments and get a weather forecast, too. Keep cycling through and you'll see a list of notifications, and pressing the run button means you can recall them straight from the watch, so you can see what you missed.

It's a surprisingly complete and useful array of smart features for such a fitness focused running watch, and for that we applaud Garmin's simple approach.

Garmin Forerunner 235: App

The Garmin Forerunner 235 is compatible with the Garmin Connect mobile app– available for iOS and Android – and you can also use it with a PC/Mac if you install the Express software.

We've written about Garmin Connect extensively, and the mobile and web services are completely different. The web tool is fantastic and filled with incredibly detailed tools for building workouts, setting routes and getting the most out of your data.

The mobile app, on the other hand, is a slightly different beast. Designed for digesting post-workout and daily activity data, it's not the best designed experience, and it can be a downright confusing at times.

But you can't say it's not in-depth. In Snapshots you can swipe through seven pages of activity data, and you can review pages of data on runs and cycles and look at graphs on aspects of your performance, too. It's messy, it's overwhelming, but it doesn't disappoint when it comes to the nitty-gritty.

Garmin Forerunner 235: Battery life

The Garmin Forerunner 235's battery life is highly impressive and lasted over a week on a single charge, with a couple of runs thrown in. A 5 mile run hardly made a dent on the battery – roughly 5% in total – so we'd have no qualms in recommending it for ultrarunners.

Garmin Forerunner 235
By Garmin
The Garmin Forerunner 235 is a solid running watch that blends top sports metrics with excellent 24/7 daily activity tracking and a lovely design. It's disappointing that the accuracy of the built-in HR monitor isn't good enough for proper high intensity workouts but it's still capable of colouring workout data for less hardcore runners and you can still pair with an ANT+ chest strap to get really serious. Pair this data with the resting heart rate info and you have a powerful tool for tracking every aspect of your health data. The device has less fun workout modes (ghost races and challenges) than the TomTom Spark but Garmin's ecosystem, sports metrics ad activity tracking are much more powerful.

  • Looks great
  • Superb activity tracking
  • Well rounded running stats
  • Optical HR tech not accurate enough
  • Garmin Connect app confusing
  • Missing fun training modes

What do you think?

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  • Xenupy·

    "All the snazzy VO2 analysis is left to the bigger, badder Garmins"... Wrong... I have it in my wrist... You miss one or two big things about this device... Connect IQ software is great and fullfill alot of things (hike, walk, gym etc...)... The fantastic connection to myfitnesspal... Everthing is connected, like food, calories etc... For exemple, i have one iHealth scale that is partner to myfitnesspal, and not to garmin connect... But because the connection (partners) my weight is connect to garmin software...

    I exchange tomtom spark because the ecosystem (it lacks alot of things) and surge because it is not accurate enough... This device fit my needs perfectly...

  • Xenupy·

    and, about the hr tracking in the wrist, if its not accurate enough (for me is the same as tomtom spark)  you can buy a chest strap and be happy and accurate... Hope this help someone...

  • Reckless·

    You guys are too picky. MIssing fun training modes? What does that even mean?

    You mention the Optical HR tech is not accurate enough yet no where in the article does it say you can pair an Ant+ HRM to it. Which was mentioned in your article about optical sensors.

    "The Garmin Forerunner 235 is a fantastic device, which will pair with ANT+ chest straps for those HIIT sessions. It's not the technology's failings that sits uncomfortably with us, it's that Garmin and Fitbit aren't being as open as Under Armour about what their tech can and can't do."

    • j.stables·

      Fun training modes were mentioned further up the review. Spark lets you run against your previous PBs, which is awesome.

      Have added a line about the ANT+ as you're right, it's important info. 

  • widespreadbliss·

    Thanks for the article/review and for to the additional commentators. I really appreciate the information.  I am thrilled to be getting this watch today.  I've been piece-milling between a very old Garmin, a fitbit and my iphone.  I think (hope) this watch is going to be the one go-to device to cover all of my novice needs.   

    Most of my runs are on a treadmill during Orange Theory classes so I am excited about the indoor running profile.  I hope that the watch will track that well enough to help me continue to push my pace.  

    Thanks again to all for taking the time to share your insights on the watch!

  • tsbrainw·

    I'm considering this watch and the VivoActive. Both of them support Smart Notification but do FR235 shows the whole message and have vibration for incoming notification?

  • Zireael·

    Hey guys, can I use this to record my gym workouts? (X-trainer, some resistance machines, rowing, watt bike etc.) I've got the Runner 2 cardio at the moment but not very happy with it as I find the daily steps tracking very inaccurate and it's not possible to change workout types in the TomTom app (or I haven't found the right button yet). Thanks!

  • gollbham·

    There are problems with battery life, especially when HRM and GPS are turned on.  Currently Garmin is working to resolve that problem.  So better to stay away until fixes are done.

    • xntriktq·

      I received this watch as a Christmas gift to replace my old 310xt. I only used it for running and rarely got the battery to last more than 4 hours total. After three months, the battery stopped taking a charge all together, and it was returned to Garmin. I am due to receive a refurbed unit this week and sure hope that battery issue is resolved. I have triathalon friends who have the 920xt, and they use it for texts, weather forcasts, regular watch, and their three sports, and get a routine 24 hours of batter life. If this watch comes back with the same problems, will buy a 920xt....

      • ndnd·

        Turn the GPS off. It's drains the battery a lot.

  • Football_Ref·

    Can someone tell me if the 235 has a stopwatch function that will alarm and vibrate particularly say at 45 minutes? I'm a Football Referee and would like it to warn me when the game time is up.

    • rexanma·

      Yes, go to Activity settings-alerts-ass new-time-choose your time!

      I hope it helped

  • Football_Ref·

    Can the watch face be changed to an analogue screen?

    What is the likelihood of accurately tracking running distance on a football field with all of the short back and forth running?

  • DishonestGarmin·

    I have a case open with Garmin at the moment, the optical HRM on the wrist is an absolute joke. I got sold on the running, riding, "other" activity settings (meaning gym, HIIT, AMRAP) sessions. I have Jabra Pulse headphones, and a MyZone chest strap whilst doing a training session, both the Jabra and MyZone were around 180-184bpm, whilst the Garmin 235 was showing 48bpm!! 
    Its also the second replacement 235 as I thought due to its complete inaccuracy it was faulty, but the replacement is just as inaccurate. Garmin need to be honest about its optical wrist HRM and say its only a guide and it only works whilst walking, running or riding, not any "Other" exercises, or they'll be heading down the same legal path as FitBit are.

    I'm going to return mine, Garmin aren't serious about data for athletes.

  • Kym·

    I have the Garmin 235, I've had issues ever since I bought it with connections to phone, the app which takes a couple of times to connect, charging afterwards the date and time changing plus recently the face cracked and I have not hit or dropped it. The charger is also tight. I've emailed Garmin and they have only offered me to replace at 50%off not a complete replacement.so no I would not buy this garmin235.

  • FishBrewRun·

    I've had mine about 10 days. I do not use any of the smart functionality except for the voice updates which are sent to my smartphone and I then hear over my bluetooth headphones.

    I've had a couple of quirks with it. 1) the heart rate was stuck at 66 bpm. This is a common problem. This was fixed by holding down the power button until the phone shuts down completely and then powering it back up. 2) the auto time/date was off, this was cured by going outside and putting it in Run and letting it satellite sync.

    It does occaisionally lose the connection to the phone but it does eventually reconnect and sync. I set mine to sync manually to save battery, it's only a couple of clicks when I want to sync.

    Battery life is amazing, I'm pretty sure they've got this nailed down now. I'm getting about a week with 50k of runs. I would like to run against my past PRs, that's about all I'm missing.

  • darchand·

    would really like to know how the HRM accuracy stacks up against the 225 with its Mio sensor, as I'm considering upgrading from the 225, and that's my only hesitation.

  • KBoom·

    Can you use the GPS without the heart rate monitor being on?

    • selki·

      Yes, you can.

  • Isaline·

    I wonder how the new garmin vivoactive HR will perform? When I look to all the features this has.

    It seems to be so great that this could probably replace the 235?

  • Disgruntled·

    Out of the blue, the watch just stops measuring heart rate and sleep. Then you get 'insights' feeling you that your sleep patterns are irregular. 

    If you don't record as runs, the heart monitor shows only normal activity. As noted earlier, the heart rate monitor can also decide it wants to show you flatlining at a given rate. 

    I like some aspects of the watch, but I'm being treated like a lab rat who is paying for the privilege to be tested. Get the updates to work properly, get the synchronisation between watch and phone to work and get the heart rate monitor to actually measure the heart rate properly. 

    • cuvball·

      So I'm not the only one experiencing this issue. Seems recent...

  • Suzeyq·

    Can you control the music on your smartphone using the watch?  Or do you have to pull your smartphone out to play, pause, etc?

  • Elissa·

    Does anybody know if you can keep your mileage running and use an additional timer? Like if I am doing a long run with pace miles and I need to track total time run and mileage separately AND I want to track pace and lap work and have a new timer going? Does that make sense?

  • Gym·

    I own this watch and I would like to congratulate you on this article.

    This is definitely the most accurate review of the 235 I've read - and I've read a lot.


  • cuvball·

    I'm on my second version of the 235, as the first went back with inability to sync up. I've had version 2 for 6 months and up until the past 2 weeks, the HRM has been spot on. However, it's now stopped reading HR during any activity and when not in activity mode, the HR it reads is suspiciously low or flatlined (I'd love to be at 74 HR immediately after a sprint). I've manually shut off/on 2x without a fix. Emailed Garmin too. So frustrating. 

  • rs_ca·

    I recently purchased the 235.  I've noticed that it can take many minutes for it to get the main screen (sometimes 15 minutes.)  The garmin logo shows on the watch face (it vibrates) and then the logo disappears.  And this continues to repeat itself.  The only way I can quickly get the watch turned on is if I plug it in to an outlet and then unplug it.  Any suggestions would be appreciated.

  • fadias·

    Can anyone tell me if the watch sounds or vibrate if we reach our day steps goal? And how work the moving alert? Thanks.

  • leechengjie·

    Is the strap of the Forerunner 235 reversible? I notice the strap has a different color on the inside and outside. I like the red accents and buttons of the watch face but not the red strap. If the red side can be reversed to face inwards with the black side facing out, that will be perfect.

  • shmuelyosef·

    Was the Optical HR sensor tested on a hairy arm? I'm curious if this makes a difference, as I am a bit gorilla-like!

  • CTrunner·

    Had the watch 10 days and everything worked great and then the heart rate monitor stopped working. Was on the phone with tech support and he basically told me that it was an internal software glitch and I needed to return it. The heart rate monitor is the biggest reason why I bought this watch. I owned the 620 and loved it. You could touch the screen to make a selection and then suddenly it stopped working as well. I could only time one event and then after I saved the event, the watch would go blank.

  • par1x·

    very disappointed with accuracy on h/rate monitor. I can be at 165 - 170 bpm and watch will register around 135. Have tried all the positions and tighter on the wrist yada yada..

    fitbit is more accurate .

    will be asking Garmin to give me a strap as the built in monitor is next to useless unless you are just interested in resting heart rate

  • Charlie-Brown·

    i am very happy in general terms but i wonder if the h rate monitor is accurate enough. I ran half marathon and giving me max 177 when i was not pacing at all fast....so more like in the 150/160 area. How much does the sweat impact accuracy? How reliable are these gadgets?

  • iael·

    Hi! I really appreciate the review, I find it really helpful!

    I have a question though, right now I'm training for a marathon and i frequently cycle and I've been thinking of buying a sports smat watch.

    Between this one (a runner friend is a BIG fan of this watch) and the Suunto Spart Sport, which one would you recommend me?

  • exerji·


    My primary use of the Forerunner 235, if I buy, will be to track steps throughout the day (as it connects to my Insurer for points; and they accept it from only a handful of devices, Garmin being one; no support for Android Wear 2.0 yet). The so called Activity Tracking - is it accurate enough? For instance, are there horror stories of someone making brief wrist movements while on a desk and they getting clocked as steps ? I may keep GPS on for 2-3 hrs each evening, to track walks I undertake and help save the tracks. Equally, I'd like to import GPX files into the watch and help me stay on track, even if offers only a limited ability, in terms of visibility. I cycle a few times a year and I'd like to get good statistics of it - even if I forget to switch on the cycling app (will Activity tracking take care of it ?). 

    In future, I would end up using it for running too, hopefully! I am not thinking of Forerunner 230 because I value GPS! I do get torn between Vivosmart HR (becaue it has got Move IQ app that detects movements automatically a bit like Google Fit) and Forerunner 235.

  • exerji·


    My primary use of the Forerunner 235, if I buy, will be to track steps throughout the day (as it connects to my Insurer for points; and they accept it from only a handful of devices, Garmin being one; no support for Android Wear 2.0 yet). The so called Activity Tracking - is it accurate enough? For instance, are there horror stories of someone making brief wrist movements while on a desk and they getting clocked as steps ? I may keep GPS on for 2-3 hrs each evening, to track walks I undertake and help save the tracks. Equally, I'd like to import GPX files into the watch and help me stay on track, even if offers only a limited ability, in terms of visibility. I cycle a few times a year and I'd like to get good statistics of it - even if I forget to switch on the cycling app (will Activity tracking take care of it ?).

    In future, I would end up using it for running too, hopefully! I am not thinking of Forerunner 230 because I value GPS! I do get torn between Vivosmart HR (becaue it has got Move IQ app that detects movements automatically a bit like Google Fit) and Forerunner 235.

  • Leerunner·

    Great device as long as you get one that works. I'm in a running club and own one of these. Not had any problems with mine (until now!) but others have had nothing but problems. Now I've managed to crack the screen. Garmin want to charge me £85 to supply me with a refurb as they "don't do repairs". No doubt the next person will get a refurb of mine that "can't be repaired". 

  • Leerunner·

    A great watch as long as you don't have any issues. I know several people with one of these in my running club and all have had problems. The problems have mainly been with accuracy or recording. 

    I have somehow broken the glass in my screen (over night in my sleep?!). Garmin don't offer repairs but will replace it with a refurbished model at a cost of £85! It's less than a year old so I want the screen replaced (which I'm happy to pay for). No doubt, the next person would get a refurbished version of my watch - that's "not repairable". 

    Steer clear of Garmin guys. 

  • Nick43·

    Does the Garmin 235 have a very basic map like the earlier forerunners?