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Circular 45mm smartwatch in Mystic Black with stainless steel case and leather strap

SAMSUNG

SAMSUNG Galaxy Watch3 45mm Mystic Black SM-R840NZKAXAC

SKU CH-NCZF-6AKPJ

45mm smartwatch with 360×360 Super AMOLED display, Bluetooth 5.0, GPS, heart-rate and ECG sensors, 1GB RAM and 8GB storage, stainless steel case, leather strap, 5ATM water resistance.

  • Connection optionsWi-Fi, Bluetooth, GPS
  • Size45 mm
  • Supported platformsAndroid / IOS
  • Built-in sensorsAccelerometer, Barometer, Gyro Sensor, Light Sensor, Optical
  • Display resolution360 × 360
  • Display typeSuper AMOLED
  • 45 mm stainless steel case with premium leather strap for a refined look
  • 360 x 360 Super AMOLED always-on display protected by Corning Gorilla Glass DX
  • Built-in GPS, Bluetooth 5.0 and Wi-Fi for phone-free connectivity
  • Comprehensive health sensors including optical heart rate, electrical heart sensor and barometer
  • 5ATM and IP68 water resistance plus military-grade durability for tough conditions

Premium 45mm smart watch

The Samsung Galaxy Watch3 in Mystic Black pairs a stainless-steel case with a premium leather strap and a 360 x 360 Super AMOLED display protected by Corning Gorilla Glass DX. It runs a Tizen Based Wearable OS 5.5 on 1GB RAM and 8GB internal storage, with Bluetooth 5.0, Wi-Fi and GPS connectivity. Sensors include an accelerometer, barometer, gyro sensor, light sensor, optical heart rate sensor and electrical heart sensor. The watch carries 5ATM and IP68 water and dust resistance.

Upgrade from basic fitness bands

Moving to this watch adds a full-colour always-on display, built-in storage for music and apps, and an electrical heart sensor for on-wrist ECG readings. The jump is worth it when you want standalone GPS tracking, contactless payments and sleep analysis without carrying a phone.

Suits Android and iOS users wanting premium health

This model fits buyers who value a classic round design, rotating bezel navigation and advanced wellness metrics in a single device. It is not for users who need cellular calling without a paired phone, or for athletes who require multi-band GNSS for precise trail mapping.

How it compares

Measured against everything we stock in Smartwatches & Wearables, at today’s prices. Recalculated every night.

Price $419.99
Pricier than about 92% of the 2,527 comparable items (median $44.99).

Specifications

Product
Brand nameSamsung
Product lineGalaxy Watch3
Model nameSM-R840NZKAXAC
Product colorMystic Black
Product typeSmart Watch
Storage
Internal storage1 GB RAM and 8 GB internal storage
Display
Display resolution360 × 360
Display typeSuper AMOLED
TouchscreenYes
Connectivity
Connection optionsWi-Fi, Bluetooth, GPS
Wireless connectivityYes
Bluetooth support5.0
Size & build
Size45 mm
Overall height1.82 in (4.62 cm)
Overall width1.77 in (4.5 cm)
Product depth0.44 in (1.12 cm)
Product weight1.9 oz
Compatibility
Supported platformsAndroid / IOS
In the box
Included itemsSamsung Galaxy Watch3 Bluetooth Smart Watch and Wireless Charger
More details
Built-in sensorsAccelerometer, Barometer, Gyro Sensor, Light Sensor, Optical Heart Rate Sensor, Electrical Heart Sensor

Questions about this item

What wrist size fits the 45mm stainless steel case with the premium leather strap?

The case measures 1.77 inches wide and 1.82 inches tall with a depth of 0.44 inches; the leather strap adjusts to fit most wrists comfortably.

How do I pair the Galaxy Watch3 via Bluetooth 5.0 to my phone, and what step is often missed?

Open the Galaxy Wearable app on Android or iOS, follow the on-screen pairing prompts, and grant all sensor permissions — skipping permission setup disables heart-rate and sleep tracking.

When should I replace the premium leather strap on the SM-R840NZKAXAC?

Replace the leather strap when it shows cracking, persistent odour, or stiffness from sweat exposure; the 5ATM and IP68 ratings protect the watch body, not the strap material.

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