Choosing a Smartwatch: What to Check Before You Buy
Smartwatches range enormously in capability at similar-looking prices. These are the things worth checking before buying, in the order they tend to cause regret.
Compatibility comes first
Check this before anything else. Some features are tied to the phone platform, and no amount of specification makes up for a mismatch.
The most common surprise: replying to messages from the watch generally works on Android and is restricted on iPhone, because iOS limits what third-party accessories can do with notifications. If replying from your wrist is the reason you are buying, verify it works with your specific phone.
Also check that the companion app is actively maintained. A watch is only as good as its app, and abandoned apps break after phone OS updates.
Display: AMOLED or LCD
AMOLED lights each pixel individually. Blacks are genuinely black, contrast is excellent, and because most watch faces are mostly black, it can use less power than you would expect. It also allows a proper always-on display.
LCD uses a backlight, so blacks look dark grey. Usually cheaper, often perfectly adequate.
Two things matter more than panel type in daily use:
- Brightness, measured in nits. A watch is used outdoors, frequently in bright sun. Low brightness makes a beautiful screen useless at midday.
- Always-on display, which lets you read the time without a wrist flick — much more natural, at a real cost in battery.
Battery claims need translating
Quoted battery figures are typically measured with the always-on display off, notifications limited, and continuous heart-rate monitoring at its least frequent setting. Turn on the features you bought the watch for and expect substantially less.
A rough translation: a claimed 7 days often means 2–3 days with always-on display and regular notifications. Ask what the figure assumes, and note whether GPS use is included — satellite positioning is the heaviest drain by a wide margin.
Sensors: useful, not medical
Be clear-eyed about what wrist sensors can do.
- Heart rate — optical sensors are reasonably good at rest and during steady activity. They struggle with rapid changes, high-intensity intervals and cold weather. A loose strap is the most common cause of bad readings; the watch should sit snug and slightly above the wrist bone.
- SpO2 (blood oxygen) — indicative at best on a wrist. Useful for spotting trends, not for diagnosis.
- Sleep tracking — good at detecting when you slept and roughly how restlessly. Sleep-stage breakdowns are estimates inferred from movement and heart rate, so treat the totals as more reliable than the stage split.
- Step counting — generally solid, with predictable errors: pushing a trolley or holding a rail undercounts.
- Blood pressure and glucose — claims here should be treated with real scepticism on consumer wrist wearables.
Consumer wearables are wellness devices. They are excellent for tracking your own trends over time and poor as substitutes for medical equipment.
GPS: built-in or borrowed
Watches with their own GPS record routes without your phone — the point of a running watch. Watches without it use the phone's GPS, which is fine if you carry your phone anyway and useless if you do not. This distinction is often blurred in listings, so look for "built-in GPS" specifically.
Calling from the watch
Many watches include a speaker and microphone and pair over Bluetooth to relay calls from your phone. This works within Bluetooth range, roughly ten metres in practice. It is not the same as a cellular watch with its own eSIM, which works independently of the phone entirely. If leaving your phone behind is the goal, you need the latter.
Water resistance
Look for an ATM rating rather than a vague "waterproof". 5ATM is suitable for swimming; 3ATM handles splashes and handwashing but not swimming. Note that ATM ratings are tested with static pressure — the dynamic force of a swimming stroke is greater. Neither rating covers hot showers, since steam and thermal cycling get past seals that cold water would not.
Straps and repairability
A small point that matters over years: check the strap uses a standard lug width (20mm and 22mm are common) with quick-release pins. Proprietary straps mean limited choice, higher prices, and a dead watch when the strap wears out and is no longer sold.
