Featured in this comparison are three fitness-focused GPS smartwatches for serious fitness enthusiasts; the Garmin Forerunner 645 vs 935 vs 945 specs and features – which is the best? While the Forerunner 945 is premium and more equipped smartwatch featuring more features, the Forerunner 645 and 935 are nice alternatives.
Table of Contents
Garmin Forerunner 645 vs 935 vs 945: Specifications Compared
| Product Info |
 Garmin Forerunner 645 Music Specifications, Features and Price |
 Garmin Forerunner 935 Specifications, Features and Price |
 Garmin Forerunner 945 Specifications, Features and Price |
|---|---|---|---|
| Price | $172.49 | $239.00 | $498.75 |
| ABOUT DEVICE | ABOUT DEVICE | ABOUT DEVICE | ABOUT DEVICE |
| Device name | Garmin Forerunner 645 Music | Garmin Forerunner 935 | Garmin Forerunner 945 |
| Device type | Fitness/Sport smartwatch | Fitness/Sport smartwatch | Fitness/Sport smartwatch |
| Gender | Unisex | Men | Men |
| Release date | November, 2017 | March, 2017 | April, 2019 |
| Predecessor | — | — | Garmin Forerunner 935 |
| Successor | — | Garmin Forerunner 945 | — |
| Versions | Garmin Forerunner 645, Garmin Forerunner 645 Music | Garmin Fenix 5, Garmin Fenix 5S, Garmin Fenix 5X | — |
| BODY | BODY | BODY | BODY |
| Dimension | 42.5 x 42.5 x 13.5 mm | 47 x 47 x 13.9 mm | 47 x 47 x 13.7 mm |
| Weight | 42.2 grams | 49 grams | 50 grams |
| Shape | Circular | Circular | Circular |
| Case material | Fiber-reinforced polymer | Fiber-reinforced polymer | Fiber-reinforced polymer |
| Strap material | Silicone | Silicone | Silicone |
| Bezel material | Stainless steel | Fiber-reinforced polymer | Fiber-reinforced polymer |
| Strap size | 20 mm | 22 mm | 22 mm |
| Screen protection | Corning Gorilla Glass 3 | Chemically strengthened glass | Corning Gorilla Glass DX |
| Water resistance | Yes, 5ATM | Yes, 5ATM | Yes, 5ATM |
| Durability test | — | — | — |
| Swim-proof | Yes, recommended | Yes, recommended | Yes, recommended |
| Color | Black, Rose-gold | Black | Black |
| DISPLAY | DISPLAY | DISPLAY | DISPLAY |
| Display size | 1.2 inches | 1.2 inches | 1.2 inches |
| Display type | LCD, Memory-in-pixel (MIP), transflective | LCD, Memory-in-pixel (MIP), transflective | LCD, Memory-in-pixel (MIP), transflective |
| Display resolution | 240 x 240 px | 240 x 240 px | 240 x 240 px |
| Pixel density | — | — | — |
| Always on | Yes | Yes | Yes |
| Custom watch face | Yes | Yes | Yes |
| Input type | (not touchscreen), 5 Physical buttons | 5 Physical buttons | (not touchscreen), 5 Physical buttons |
| CONNECTIVITY | CONNECTIVITY | CONNECTIVITY | CONNECTIVITY |
| Bluetooth | ANT+, Bluetooth | ANT+, Bluetooth | ANT+, Bluetooth |
| Bluetooth calling | No | No | No |
| GPS | Galileo, GLONASS, GPS | Galileo, GLONASS, GPS | Galileo, GLONASS, GPS |
| NFC | Yes | No | Yes |
| Wi-Fi | Yes, Wi-Fi 802.11 b/g/n | Yes, Wi-Fi 802.11 b/g/n | Yes, Wi-Fi 802.11 b/g/n |
| MEMORY | MEMORY | MEMORY | MEMORY |
| RAM | — | — | — |
| ROM | 4GB | 64MB | 8GB |
| Memory card slot | No | No | No |
| CELLULAR CONNECTIVITY | CELLULAR CONNECTIVITY | CELLULAR CONNECTIVITY | CELLULAR CONNECTIVITY |
| Technology | None | None | None |
| SIM type | None | None | None |
| Band | — | — | — |
| NOTIFICATIONS | NOTIFICATIONS | NOTIFICATIONS | NOTIFICATIONS |
| SMS alert | Yes | Yes | Yes |
| Calls alert | Yes | Yes | Yes |
| Email alert | Yes | Yes | Yes |
| Event reminder | Yes | Yes | Yes |
| Third-party apps alert | Yes | Yes | Yes |
| MEDIA | MEDIA | MEDIA | MEDIA |
| Audio | mp3/mp4 | No | mp3/mp4 |
| Bluetooth music | Yes | No | Yes |
| Loudspeaker | No | No | No |
| Microphone | No | No | No |
| Camera | No | No | No |
| Radio | No | No | No |
| SENSORS | SENSORS | SENSORS | SENSORS |
| Accelerometer | Yes | Yes | Yes |
| Altimeter | Yes | Yes | Yes |
| Ambient light | Yes | Yes | Yes |
| Barometer | Yes | Yes | Yes |
| Compass | Yes | Yes | Yes |
| ECG | No | No | No |
| Gyroscope | Yes | Yes | Yes |
| HRM | Yes | Yes | Yes |
| Pulse oximeter (SpO2) | No | No | Yes |
| Thermometer | Yes | Yes | Yes |
| Other sensors | — | — | — |
| ACTIVITY TRACKING | ACTIVITY TRACKING | ACTIVITY TRACKING | ACTIVITY TRACKING |
| Blood oxygen | No | — | Yes |
| Blood Pressure | No | No | No |
| Calories | Yes | Yes | Yes |
| Distance | Yes | Yes | Yes |
| ECG tracking | No | No | No |
| Heart rate monitoring | Yes | Yes | Yes |
| Sleep tracking | Yes | Yes | Yes |
| Steps | Yes | Yes | Yes |
| Floors climbed | Yes | Yes | Yes |
| Stress | Yes | Yes | Yes |
| Incidental fall detection | Yes | No | Yes |
| Menstrual cycle | No | Yes | Yes |
| VO2 Max | Yes | Yes | Yes |
| Swim-tracking | Yes | Yes | Yes |
| Underwater heart rate tracking | No | No | Yes |
| On-screen workout | No | No | No |
| Sport modes | Yes | Yes | Yes |
| BATTERY | BATTERY | BATTERY | BATTERY |
| Battery type | non-removable Lithium-polymer | non-removable Lithium-polymer | non-removable Lithium-polymer |
| Battery capacity | — | — | — |
| Battery life | GPS with music: 5hrs, Smartwatch mode: 7 days | GPS/HR mode: Up to 24 hours, Smartwatch mode: Up to 2 weeks, Ultratrac: up to 60hrs | GPS with music: up to 10hrs, Smartwatch mode: Up to 2 weeks, Ultratrac: up to 60hrs |
| Charging type | Charging dock | Charging dock | Charging dock |
| Charging time | 1-2 hours | 1-2 hours | 1-2 hours |
| Solar power | No | No | No |
| PLATFORM | PLATFORM | PLATFORM | PLATFORM |
| Chipset | — | — | — |
| CPU | — | — | — |
| GPU | — | — | — |
| Operating system | Proprietary OS | Proprietary OS | Proprietary OS |
| MISC | MISC | MISC | MISC |
| Companion app | Garmin Connect | Garmin Connect | Garmin Connect |
| Compatibility | Android, iOS | Android, iOS | Android, iOS |
| Payment system | Garmin Pay | None | Garmin Pay |
| Interchangeable strap | 20mm, Yes | 22 mm, Yes | 22 mm, Yes |
| Voice command | No | No | No |
| Find my phone | Yes | Yes | Yes |
| Box content | Charger, Garmin Forerunner 645 Music, Manual, Straps | Charger, Garmin Forerunner 935, Manual, Straps | Charger, Garmin Forerunner 945, Manual, Straps |
| Price | $172.49 | $239.00 | $498.75 |
Garmin Forerunner 645 vs 935 vs 945: Fitness Tracking Features
| Garmin Forerunner 645 | Garmin Forerunner 935 | Garmin Forerunner 945 | |
| Activity Tracking Features Steps counter, floors climbed, fitness age, Move IQ intensity minutes and distanced traveled. | Yes | Yes | Yes |
| Body Battery Energy Monitor Lets you see your body’s energy levels throughout the day so you can find the best times for activity and rest. | No | No | Yes |
| Pulse OX Sensor The Pulse Ox sensor gauges your blood oxygen saturation during the day and as you sleep to show how well your body is absorbing oxygen. | No | No | Yes |
| Stress Tracking Helps you find out if you’re having a calm, balanced or stressful day. Relax reminders will even prompt you to do a short breathing activity when you’re feeling stressed. | Yes | Yes | Yes |
| Menstrual Cycle Tracking Lets you use the Garmin Connect™ app to track your cycle, log physical and emotional symptoms and learn about training and nutrition during each phase of your cycle. Even get cycle tracking information on your wrist. | No | Yes | Yes |
| Hydration Tracking Log your daily fluid intake as a reminder to stay hydrated. You can even have an auto goal for hydration that adjusts based on how much sweat you lose during activities — even underwater. | No | No | Yes |
| Respiration Tracking See how you’re breathing throughout the day, during sleep and during breath-work and yoga activities. | No | No | Yes |
| Advanced Sleep Monitoring Get a full picture of how you’re sleeping, with a breakdown of your light, deep and REM sleep stages as well as Pulse Ox and respiration data | Yes | Yes | Yes |
| Heart Rate Tracking The watch constantly samples your heart rate2 and will alert you if it stays high while you’re at rest. It also helps gauge how hard you work during activities even underwater. | Yes | Yes | Yes |
| Mindful Breathing When you want to relax or focus, you can start a breath-work activity, and this watch will track your stress and respiration to help you get a better understanding of how you’re breathing. | No | No | No |
| On-Screen Animated Workout Modes Easy-to-follow, animated cardio, strength, yoga and Pilates workouts come preloaded on the watch, and you can download more from the Garmin Connect app. | No | No | No |
| Preloaded Workout Modes Track all the ways you move with more than 20 preloaded GPS and indoor sports apps — including walking, running, cycling, pool swimming, golf and more. | Yes | Yes | Yes |
| Garmin Coach Get a personal running coach on your wrist, for free, to help you train for your next 5K, 10K or half-marathon. | Yes | Yes | Yes |
| Safety and Tracking Features When your watch and phone are paired, your live location can be sent to your contacts manually or — during outdoor activities — automatically with built-in incident detection. Also Livetrack, Group LiveTrack and Live event sharing allow you to invite other to join you in your training. | Yes, lacks Group LiveTrack, Assistance and Live event sharing | Yes, lacks Assistance, Live event sharing, and incidental fall detection | Yes |
| Gym & Fitness Equipment Available gym profiles; Strength, Cardio and Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing, Pilates and Yoga. | Fewer | Fewer | More |
| Training, Planning and Analysis Features Available run profiles; Running, Treadmill Running, Indoor Track Running, Trail Running. GPS speed and distance, customizable activity profiles, advanced training, VO2 Max., heat and altitude acclimation, training load, training effect, auto and manual mutisport activities, Garmin and Strava live segments. | Fewer | Fewer | More |
| ClimbPro Feature Use ClimbPro ascent planner on downloaded courses to see real-time information on your current and upcoming climbs, including gradient, distance and elevation gain. | No | No | Yes |
| Outdoor Recreation Features Outdoor recreational features include hiking, climbing, mountain biking, skiing, snowboarding, XC skiing, stand up paddleboarding, rowing, kayaking, jumpmaster, tactical | Fewer | Fewer | More |
| Multi-GNSS Support Access multiple global navigation satellite systems (GPS, GLONASS and Galileo) to track in more challenging environments than GPS alone. | Yes | Yes | Yes |
| TOPO Maps Preloaded Topographical (TOPO) maps allow you use TOPO maps with Trendline Popularity Routing to find the best routes and navigate your adventures effortlessly | No | No | Yes |
| Ski Maps Preloaded Ski maps allow you view run names and difficulty ratings for 2,000 worldwide ski resorts. | No | No | No |
| Round-trip Routing Enter a distance you want to travel, and get suggested routes that will bring you back to your starting point. Trendline™ popularity routing helps you find the best local paths. | No | No | Yes |
| Turn-by-turn Navigation Follow a route or course with help from turn-by-turn directions, which let you know ahead of time when the next turn is coming. | Yes | Yes | Yes |
| ABC sensors Navigate your next trail with ABC sensors, including an altimeter for elevation data, barometer to monitor weather and three-axis electronic compass | Yes | Yes | Yes |
| Running Features Available run profiles include running, treadmill running, indoor track running, trail running | Fewer | Fewer | More |
| PACEPRO Technology A first-of-its-kind PacePro feature helps keep you on pace with grade-adjusted guidance as you run a course. | No | No | Yes |
| Golf Courses Access full-color CourseView maps for more than 41,000 golf courses around the world, and get button targeting and the PlaysLike Distance feature. | No | Yes | Yes |
| Swimming Features Available swimming profiles; pool swimming, open water swimming, swimming/running. Other features include; tracks metrics such as distance, pace, stroke count, stroke distance and SWOLF. | Fewer | Fewer | More |
| Underwater Wrist-based Heart Rate Tracking Features underwater wrist-based heart rate tracking that helps you manage your swimming intensity. | No | No | Yes |
| Altimeter Floors climbed | Yes | Yes | Yes |
Garmin Forerunner 645 vs 935 vs 945: Battery Life
| Forerunner 645 | Forerunner 935 | Forerunner 945 |
| Smartwatch Mode: Up to 7 days GPS mode with music: Up to 5 hours GPS mode without music: Up to 14 hours |
Smartwatch Mode: Up to 2 weeks GPS/HR mode: Up to 24 hours UltraTrac™ mode: Up to 60 hours without wrist heart rate |
Smartwatch Mode: Up to 2 weeks GPS mode with music: Up to 10 hours GPS mode without music: Up to 36 hours |
Garmin Forerunner 645 vs 935 vs 945: Editor’s Pick
