A lighter watch is more comfortable to wear all day.

The case diameter; larger cases fit bigger displays, smaller ones suit slimmer wrists.

The case material (e.g. aluminium, titanium).

A higher ATM rating allows swimming and diving.

Shows the time and stats without raising your wrist.

A scratch-resistant sapphire crystal protects the screen.

The case and band colour options the watch is sold in.

A larger display is easier to read and interact with.

A higher pixel count produces sharper text and graphics.

The screen technology (e.g. AMOLED).

A brighter screen is easier to read in sunlight.

Continuously tracks your heart rate.

Measures blood-oxygen saturation.

Takes an electrocardiogram to check heart rhythm.

Estimates blood pressure from the wrist.

Monitors sleep stages and quality.

Tracks routes and distance without a phone.

Senses skin temperature for health insights.

Detects hard falls and can call for help.

More tracked workout types suit more activities.

Estimated hours of use between charges.

Tops up quickly from empty.

Charges on a wireless pad or puck.

How long a full charge takes; lower is better.

A newer Bluetooth version improves range and efficiency.

Connects to Wi-Fi for updates and sync without a phone.

L1+L5 GPS gives more accurate tracking in cities and forests.

Make calls and stream without your phone nearby.

Pay contactlessly from your wrist.

Take calls and use a voice assistant on the watch.

The watch software platform.

More storage holds more offline music and apps.