Garmin Forerunner® 245 vs Garmin Forerunner® 645Size, Specs & Wrist Fit Compared
The Garmin Forerunner® 245 and Garmin Forerunner® 645 share a near-identical 42.3mm case, so wrist presence comes down to thickness, lug-to-lug and weight.
The Garmin Forerunner® 245 is the slimmer of the two (12.2mm vs 13.5mm), so it slides under a cuff more easily.
On the wrist the Garmin Forerunner® 245 feels lighter (38.5g vs 41.8g, case only).
Specification Comparison
| Spec | GarminForerunner® 245 | GarminForerunner® 645 |
|---|---|---|
| Case Width | 42.3mm | 42.5mm |
| Thickness | 12.2mm | 13.5mm |
| Weight | 38.5g | 41.8g |
| Shape | Circular | Circular |
| GPS | Yes | Yes |
| Battery Life | Smartwatch Mode: Up to 7 daysGPS mode: Up to 24 hours | Smartwatch Mode: Up to 7 daysGPS mode: Up to 14 hours |
| Display | Sunlight-visible, transflective memory-in-pixel (MIP) | — |
| Released | 2019 | 2018 |
Full Specification Comparison
160 specs| Spec | Garmin Forerunner® 245 | Garmin Forerunner® 645 |
|---|---|---|
| Overview | ||
| Family | Garmin | Garmin |
| General | ||
| Battery life | Smartwatch Mode: Up to 7 daysGPS mode: Up to 24 hours | Smartwatch Mode: Up to 7 daysGPS mode: Up to 14 hours |
| Display Size | 1.2" (30.4 mm) diameter | 1.2" (30.4 mm) diameter |
| Color display | Yes | Yes |
| Lens Material | Corning® Gorilla® Glass 3 | Corning® Gorilla® Glass 3 |
| Bezel Material | fiber-reinforced polymer | stainless steel |
| Memory/History | 4 GB | 200 hours of activity data |
| Strap material | silicone | silicone |
| Charging method | Garmin proprietary plug charger | — |
| Display resolution | 240 x 240 pixels | 240 x 240 pixels |
| Quick Release bands | yes (20 mm, Industry standard) | yes (20 mm, Industry standard) |
| Sensors | ||
| GPS | Yes | Yes |
| Compass | Yes | Yes |
| GLONASS | Yes | Yes |
| Galileo | Yes | Yes |
| Thermometer | yes (tempe™ sensor required) | Yes |
| Accelerometer | Yes | Yes |
| Pulse Ox Blood Oxygen Saturation Monitor | Yes | — |
| Garmin Elevate™ wrist heart rate monitor | Yes | Yes |
| Gyroscope | — | Yes |
| Barometric altimeter | — | Yes |
| Product Info | ||
| Main SKU | 010-02120-00 | 010-01863-00 |
| Product ID | 628939 | 591311 |
| Product Name | Forerunner® 245 | Forerunner® 645 |
| Release Date | 4/30/2019 | 1/9/2018 |
| Product Variation | Slate Gray | Black with Stainless Hardware |
| Clock Features | ||
| Timer | Yes | Yes |
| Stopwatch | Yes | Yes |
| Time/date | Yes | Yes |
| Alarm clock | Yes | Yes |
| GPS Time Sync | Yes | Yes |
| Sunrise/sunset times | Yes | Yes |
| Automatic daylight saving time | Yes | Yes |
| Cycling Features | ||
| Courses | Yes | Yes |
| Race an activity | Yes | Yes |
| Compatible with Varia™ lights | Yes | Yes |
| Speed and cadence sensor support (w/sensor) | Yes | Yes |
| Compatible with Varia™ radar (rear-facing radar) | Yes | Yes |
| Compatible with Varia Vision™ (head-mounted display) | Yes | Yes |
| Alerts (triggers alarm when you reach goals including time, distance, heart rate or calories) | Yes | Yes |
| Running Features | ||
| Run workouts | Yes | Yes |
| Race predictor | Yes | Yes |
| Foot pod capable | Yes | Yes |
| Running dynamics | yes (with compatible accessory) | Yes |
| Performance condition | Yes | Yes |
| Run/Walk/Stand detection | Yes | — |
| Stride length (real time) | yes (with compatible accessory) | — |
| PacePro™ Pacing Strategies | Yes | — |
| Vertical oscillation and ratio | yes (with compatible accessory) | — |
| Ground contact time and balance | yes (with compatible accessory) | — |
| GPS-based distance, time and pace | Yes | Yes |
| Cadence (provides real-time number of steps per minute) | Yes | Yes |
| What You'll Love | ||
| Display type | Sunlight-visible, transflective memory-in-pixel (MIP) | — |
| Water rating | 5 ATM | — |
| Training status | Yes | Yes |
| Pulse Ox blood oxygen | yes (spot-check and optionally in sleep) | — |
| Battery life (smartwatch mode) | Up to 7 days | — |
| Garmin Pay™ | — | Yes |
| Activity Profiles | ||
| Gym | Strength, Cardio, Elliptical Training, Stair Stepping, Indoor Rowing | Strength, Cardio and Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing and Yoga |
| Swim | Pool Swimming | Pool Swimming |
| Cycling | Biking, Indoor Biking | Biking, Indoor Biking |
| Wellness | Walking, Yoga | — |
| Indoor running | Treadmill Running, Indoor Track Running, Virtual Running | — |
| Outdoor running | Running, Outdoor Track Running, Trail Running | — |
| Outdoor recreation | — | Skiing, Snowboarding, XC Skiing, Stand up Paddleboarding, Rowing |
| Swimming Features | ||
| Pool swim workouts | Yes | Yes |
| Auto rest (pool swim only) | Yes | — |
| Drill logging (pool swim only) | Yes | Yes |
| Underwater wrist-based heart rate | Yes | — |
| "Repeat on" rest timer (pool swim only) | Yes | Yes |
| Basic rest timer (up from 0) (pool swim only) | Yes | Yes |
| Stroke type detection (freestyle, backstroke, breaststroke, butterfly) (pool swim only) | Yes | Yes |
| Pool swim metrics (lengths, distance, pace, stroke count, swim efficiency (SWOLF), calories) | Yes | Yes |
| Countdown start (pool swim only) | — | Yes |
| Outdoor Recreation | ||
| TracBack® | Yes | Yes |
| Back to start | Yes | Yes |
| UltraTrac mode | Yes | Yes |
| GPS coordinates | Yes | Yes |
| Distance to destination | Yes | Yes |
| Point-to-point navigation | Yes | Yes |
| Bread crumb trail in real time | Yes | Yes |
| Vertical speed | — | Yes |
| Elevation profile | — | Yes |
| Total ascent/descent | — | Yes |
| Daily Smart Features | ||
| Calendar | Yes | Yes |
| Connectivity | Bluetooth®, ANT+® | Bluetooth®, ANT+®, Wi-Fi® |
| Find My Phone | Yes | Yes |
| Find My Watch | Yes | Yes |
| VIRB® Remote | Yes | Yes |
| Weather forecasts | Yes | Yes |
| Smart Notifications | Yes | Yes |
| Smartphone compatibility | iPhone® and Android™ | iPhone® and Android™ |
| Controls smartphone music | Yes | Yes |
| Pairs with Garmin Connect™ Mobile | Yes | Yes |
| Text response/reject phone call with text (Android™ only) | Yes | Yes |
| Connect IQ™ (downloadable watch faces, data fields and apps) | Yes | Yes |
| Activity Tracking Features | ||
| TrueUp™ | Yes | Yes |
| Move IQ™ | Yes | Yes |
| Step counter | Yes | Yes |
| Calories burned | Yes | Yes |
| Distance traveled | Yes | Yes |
| Intensity minutes | Yes | Yes |
| Automatic rep counting | Yes | Yes |
| Garmin Connect™ Challenges app | yes (optional Connect IQ app) | yes (optional Connect IQ app) |
| Move alerts (displays on device after a period of inactivity) | Yes | Yes |
| Auto goal (learns your activity level and assigns a daily step goal) | Yes | Yes |
| Floors climbed | — | Yes |
| Workout and Training Plans | ||
| Cardio workouts | Yes | Yes |
| Strength workouts | Yes | Yes |
| Health & Wellness Monitoring | ||
| Sleep | yes (advanced) | yes (advanced) |
| Hydration | yes (in Garmin Connect™ and optional Connect IQ™ widget) | yes (in Garmin Connect™ and optional Connect IQ™ widget) |
| Fitness age | yes (in app) | yes (in app) |
| All-day stress | Yes | Yes |
| Women's health | yes (in Garmin Connect™ and optional Connect IQ™ widget) | yes (in Garmin Connect™ and optional Connect IQ™ widget) |
| Resting heart rate | Yes | Yes |
| Abnormal heart rate alerts | yes (high and low) | — |
| Relaxation breathing timer | Yes | Yes |
| Body Battery™ energy monitor | Yes | — |
| Wrist-based heart rate (constant, every second) | Yes | Yes |
| Safety and Tracking Features | ||
| Assistance | Yes | — |
| Live Event Sharing | Android™ Only | — |
| Incident Detection during select activities | Yes | — |
| Incident detection alert on phone for wearables | Yes | — |
| Kid Activity Tracking Features | ||
| Toe-to-Toe™ Challenges app | yes (optional Connect IQ Toe-to-Toe™ Challenges app) | yes (optional Connect IQ Toe-to-Toe™ Challenges app) |
| Training, Planning and Analysis Features | ||
| % HRR | Yes | Yes |
| % HR max | Yes | Yes |
| HR zones | Yes | Yes |
| HR alerts | Yes | Yes |
| Manual lap | Yes | Yes |
| Auto max HR | Yes | Yes |
| Auto scroll | Yes | Yes |
| Finish time | Yes | Yes |
| HR calories | Yes | Yes |
| Voice alerts | Yes | Yes |
| Custom alerts | Yes | Yes |
| Physio TrueUp | Yes | Yes |
| Recovery time | Yes | Yes |
| Training load | Yes | Yes |
| VO2 Max (Run) | Yes | Yes |
| Course guidance | Yes | Yes |
| Training effect | Yes | Yes |
| Virtual Partner | Yes | Yes |
| Race an Activity | Yes | Yes |
| Advanced workouts | Yes | Yes |
| Interval training | Yes | Yes |
| GPS speed and distance | Yes | Yes |
| Improved recovery time | Yes | — |
| Configurable lap alerts | Yes | Yes |
| Customizable data pages | Yes | Yes |
| Touch and/or button lock | Yes | Yes |
| Activity history on watch | Yes | Yes |
| Downloadable training plans | Yes | Yes |
| Training effect (anaerobic) | Yes | Yes |
| HRM running pace and distance | Yes | — |
| Customizable activity profiles | Yes | Yes |
| Auto Pause® automatic timer halt | Yes | Yes |
| Auto Lap® interval tracking feature | Yes | Yes |
| HR broadcast (broadcasts HR data over ANT+® to paired devices) | yes (using ANT+ or BLE) | Yes |
| Garmin Live Segments | — | Yes |
| Strava Live Segments | — | Yes |
Wrist Fit
Garmin Forerunner® 245
Sits best on wrists ~45–60mm wide (≈ 12.0–16.0cm circumference).
Garmin Forerunner® 645
Sits best on wrists ~45–61mm wide (≈ 12.0–16.3cm circumference).
2D Dimension Schematics
Accurate scale drawings based on case dimensions. Drag to pan, Ctrl+scroll to zoom. Works for every watch regardless of photo availability.
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Product Photos
Side-by-side product images at matched scale.
Garmin Forerunner® 245 (010-02120-00)
42.3mm × 42.3mm
Garmin Forerunner® 645 (010-01863-00)
42.5mm × 42.5mm
Frequently Asked Questions
Is the Garmin Forerunner® 245 bigger than the Garmin Forerunner® 645?
The Garmin Forerunner® 645 is bigger — 42.5mm vs 42.3mm case width.
Which fits a smaller wrist better, the Garmin Forerunner® 245 or the Garmin Forerunner® 645?
The Garmin Forerunner® 245 suits wrists around 45–60mm wide, and the Garmin Forerunner® 645 around 45–61mm. The one with the smaller lower bound is the safer pick for a small wrist.
Can I see the Garmin Forerunner® 245 and Garmin Forerunner® 645 side by side at true scale?
Yes — the schematics and photos above show both watches at matched scale, and our fit tool overlays each on your wrist width.
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