Garmin Descent Mk3i 51mm vs Tactix 8 47mm AMOLED
Size, specs & wrist fit compared
Which one fits you
Under 18 cm (7.1 in) round, the Descent Mk3i 51mm's lugs overhang and the Tactix 8 47mm AMOLED's do not; the Tactix 8 47mm AMOLED fills the wrist at 17.5–19.5 cm, the Descent Mk3i 51mm at 19 cm and up.
What else differs
- Battery: 25 days for the Descent Mk3i 51mm against 16 days for the Tactix 8 47mm AMOLED in everyday use; 3.2 days for the Descent Mk3i 51mm against 47 hours for the Tactix 8 47mm AMOLED with GPS on.
2.6mm thinner, the Tactix 8 47mm AMOLED is the one that slides under a shirt cuff.
The Descent Mk3i 51mm is 4mm wider, 2.6mm thicker and 4.8g heavier than the Tactix 8 47mm AMOLED.
Descent Mk3i 51mm
Tactix 8 47mm AMOLED
Case width
51mm
47mm−4mm
Thickness
16.4mm
13.8mm−2.6mm
Weight
77.8g
73g−4.8g
Descent Mk3i 51mm or Tactix 8 47mm AMOLED by wrist size
| Wrist round (mm left each side) | Descent Mk3i 51mm≈58.5mm lug to lug, est. | Tactix 8 47mm AMOLED≈54mm lug to lug, est. |
|---|---|---|
| 14 cm / 5.5 in | Overhangs (6.7mm over) | Overhangs (4.4mm over) |
| 15 cm / 5.9 in | Overhangs (5.1mm over) | Overhangs (2.8mm over) |
| 16 cm / 6.3 in | Overhangs (3.4mm over) | Overhangs (1.2mm over) |
| 17 cm / 6.7 in | Overhangs (1.8mm over) | Bold (0.4mm) |
| 18 cm / 7.1 in | Overhangs (0.2mm over) | Sweet spot (2mm) |
| 19 cm / 7.5 in | Bold (1.4mm) | Sweet spot (3.6mm) |
| 20 cm / 7.9 in | Sweet spot (3mm) | Balanced (5.3mm) |
Switch or add watches
Garmin
Descent Mk3i 51mm
Garmin
Tactix 8 47mm AMOLED
As an Amazon Associate, WatchFitTool earns from qualifying purchases.
Battery life compared
Furthest apart in All systems with music mode, where the Descent Mk3i 51mm lasts 1.7× as long as the Tactix 8 47mm AMOLED (17 hours against 10 hours).
Descent Mk3i 51mmTactix 8 47mm AMOLED
Battery saver
31 days23 daysSmartwatch
25 days16 daysExpedition
24 days17 daysMax battery GPS
118 hours81 hoursGPS only
76 hours47 hoursDive
66 hours—All systems
55 hours38 hoursAll systems + multi-band
48 hours35 hoursDive with Air Integration
40 hours—All systems with music
17 hours10 hours
More comparisons
2D Dimension Schematics
- Garmin Descent Mk3i 51mm 51mm × ≈58.5mm (est.) · 16.4mm thick
- Garmin Tactix 8 47mm AMOLED 47mm × ≈54mm (est.) · 13.8mm thick
3D preview
Descent Mk3i 51mm vs Tactix 8 47mm AMOLED on a wrist
Specifications
The short version
7 key specs| Spec | GarminDescent Mk3i 51mm | GarminTactix 8 47mm AMOLED |
|---|---|---|
| Case Width | 51mm | 47mm |
| Thickness | 16.4mm | 13.8mm |
| Weight | 77.8g | 73g |
| Shape | Circular | Circular |
| Display type | AMOLED | AMOLED |
| Battery life | Smartwatch: Up to 25 days (10 days always-on) Battery Saver Watch Mode: Up to 31 days GPS Only: Up to 76 hours (56 hours always-on) All Satellite Systems: Up to 55 hours (43 hours always-on) All Satellite Systems + Multi-band: Up to 48 hours (38 hours always-on) All Satellite Systems + Music: Up to 17 hours Max Battery GPS: Up to 118 hours Expedition GPS: Up to 24 days Dive Mode: Up to 66 hours Dive Mode with Air Integration: Up to 40 hours | Smartwatch: Up to 16 days (7 days always-on) Battery Saver Watch Mode: Up to 23 days GPS Only: Up to 47 hours (37 hours always-on ) All Satellite Systems: Up to 38 hours (30 hours always-on) All Satellite Systems + Multi-band: Up to 35 hours (28 hours always-on)* All Satellite Systems + Music: Up to 10 hours Max Battery GPS: Up to 81 hours Expedition GPS: Up to 17 days *Assuming typical use with SatIQ technology |
| Released | 2023 | 2025 |
Where the specifications differ
40 differences| Spec | Garmin Descent Mk3i 51mm | Garmin Tactix 8 47mm AMOLED |
|---|---|---|
| General | ||
| Battery life | Smartwatch: Up to 25 days (10 days always-on) Battery Saver Watch Mode: Up to 31 days GPS Only: Up to 76 hours (56 hours always-on) All Satellite Systems: Up to 55 hours (43 hours always-on) All Satellite Systems + Multi-band: Up to 48 hours (38 hours always-on) All Satellite Systems + Music: Up to 17 hours Max Battery GPS: Up to 118 hours Expedition GPS: Up to 24 days Dive Mode: Up to 66 hours Dive Mode with Air Integration: Up to 40 hours | Smartwatch: Up to 16 days (7 days always-on) Battery Saver Watch Mode: Up to 23 days GPS Only: Up to 47 hours (37 hours always-on ) All Satellite Systems: Up to 38 hours (30 hours always-on) All Satellite Systems + Multi-band: Up to 35 hours (28 hours always-on)* All Satellite Systems + Music: Up to 10 hours Max Battery GPS: Up to 81 hours Expedition GPS: Up to 17 days *Assuming typical use with SatIQ technology |
| Display Size | 1.4” diameter (35.56 mm) | 1.4” (35.56 mm) diameter |
| Bezel Material | Diamond-like Carbon (DLC) coated titanium | titanium |
| Strap material | silicone or DLC coated titanium | silicone |
| Charging method | Garmin proprietary clip charger | Garmin proprietary plug charger |
| QuickFit® watch band compatible | yes (26 mm) | included (22 mm) |
| Sensors | ||
| Depth sensor | Yes | yes (to 40 m) |
| Product Info | ||
| Main SKU | 010-02752-10 | 010-03405-00 |
| Product ID | 852159 | 1828661 |
| Product Name | Descent™ Mk3i – 51 mm | tactix® 8 – 47 mm, AMOLED |
| Release Date | 11/15/2023 | 2/14/2025 |
| Product Variation | Carbon Gray DLC Titanium with Black Silicone Band | Includes Applied Ballistics Ultralight™ Solver |
| Diving Features | ||
| PO2 | Up to 2.0 with customizable deco PO2 setting | Up to 1.6 with customizable Deco settings |
| Backlight | yes (configurable time and intensity; auto-on at depth) | yes (configurable intensity; always on) |
| Gas mixes | Air, Nitrox and Trimix, up to 100% O2; 1 bottom gas and up to 11 deco and/or backup gasses. | Air, Nitrox (21-40% Oxygen) |
| Deep Stops | yes (using custom gradient factors) | yes (using custom Gradient Factors) |
| Safety Stop | yes (customizable off/3min/5min) | yes (customizable Off/3min/5min) |
| Dive planner | yes (basic NDL + multi-gas deco planner) | yes (Basic NDL & Gas Planner) |
| Alerts & alarms | Audible and vibration alarms for ascent rate, PO2, CNS/OTU, NDL, deco, gas switching, tank pressure, gas consumption rate. Customizable (up to 40) audible and/or vibration per dive mode, based on depth or time | yes (vibration only) |
| 3-axis dive compass | yes (with adjustable heading, quick change to 90R, 90L and reciprocal). Indicates degrees and direction back to set heading | yes (with adjustable heading, quick change to 90R, 90L, and Reciprocal. Indicates degrees and direction back to set heading) |
| Decompression model | Bühlmann ZHL-16c with gradient factors | Bühlmann ZHL-16c w/ Gradient Factors |
| Custom end-dive timeout | yes (20s to 10 m) | yes (20 sec to 10 min) |
| Customizable conservatism | yes (low/medium/high or custom using gradient factors) | yes (Low/Medium/High) |
| Surface diver status widget | yes (surface interval, N2/HE loading, CNS, OTU and tissue compartment status) | yes (surface Interval, no fly time, N2 loading, CNS, OTU, and Tissue Compartment status) |
| Dive activity maximum operating depth | 200 meters | 40 meters |
| Running Features | ||
| Ground contact time and balance | Yes | yes (GCT balance with accessory) |
| What You'll Love | ||
| Water rating | Dive (200 meters) | 10 ATM |
| Training status | yes (improved) | Yes |
| Battery life (smartwatch mode) | Up to 25 days (10 days always-on) | Up to 16 days (7 days always-on) |
| Activity Profiles | ||
| Gym | Strength, HIIT, Cardio, Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing | Strength, HIIT, Cardio, Elliptical Training, Stair Stepping, Floor Climbing, Indoor Rowing, Jump Roping |
| On the Water | Stand Up Paddleboarding, Rowing, Kayaking, Surfing, Kiteboarding, Windsurfing, Fishing, Boating, Sailing, Sail Racing, Water Skiing, Wakeboarding, Wakesurfing, Tubing, Snorkeling, Sailing Expedition, Whitewater | Stand Up Paddleboarding, Rowing, Kayaking, Surfing, Kiteboarding, Windsurfing, Fishing, Boating, Sailing, Water Skiing, Wakeboarding, Wakesurfing, Tubing, Snorkeling, Whitewater |
| Snow & winter | Skiing, Snowboarding, Backcountry Snowboarding, XC Classic Skiing, Backcountry Skiing, Ice Skating, Snowshoeing | Skiing, Snowboarding, Backcountry Snowboarding, XC Classic Skiing, XC Skate Skiing, Backcountry Skiing, Ice Skating, Snowshoeing |
| Outdoor recreation | Hiking, Indoor Climbing, Bouldering, Climbing, Hunting, Horseback Riding, Golfing, Disc Golf, Archery | Hiking, Rucking, Indoor Climbing, Bouldering, Climbing, Hunting, Horseback Riding, Golfing, Disc Golf, Archery |
| Other activity profiles | Jumpmaster, Tactical, Inline Skating | Flying, Jumpmaster, Tactical, Inline Skating |
| Tactical Features | ||
| Ballistics solver | yes (unlock required) | Yes |
| Outdoor Recreation | ||
| Preloaded road and trail maps | Yes | yes (Sapphire Editions only) |
| Daily Smart Features | ||
| Connectivity | Bluetooth®, ANT+®, Wi-Fi®, Subwave™ | Bluetooth®, ANT+®, Wi-Fi® |
| Health & Wellness Monitoring | ||
| Hydration | yes (in Garmin Connect™) | yes (in Garmin Connect™ and optional Connect IQ™ widget) |
| Fitness age | yes (in app) | Yes |
| Women's health | yes (in Garmin Connect™) | yes (in Garmin Connect™ and optional Connect IQ™ widget) |
The other 281 specifications both list are identical.
Full Garmin Descent Mk3i 51mm specifications →Full Garmin Tactix 8 47mm AMOLED specifications →