Heart-rate sensor accuracy
Optical sensor quality and sampling rate.
Why it matters
Cheap sensors lag badly during interval workouts, making training data useless.
What to check
Continuous monitoring drains battery; check the rated life with it on.
Electronics
Smartwatch & Fitness Band
Watches advertise 150 sports modes and SpO2. What actually matters is heart-rate accuracy during movement, GPS quality if you run, and whether it survives a week off the charger.
Find your fit
A few questions about your situation, not about the product.
Answer all 3 questions to see the spec sheet to shop with.
The spec sheet, decoded
Built-in GPS vs connected GPS
Own GPS chip vs borrowing the phone's.
Why it matters
Runners and cyclists need built-in GPS to leave the phone at home.
What to check
'GPS' in the spec list often means connected GPS only.
Display type & brightness (nits)
AMOLED vs LCD and outdoor visibility.
Why it matters
Under Indian sun, below 500 nits is unreadable.
What to check
Always-on display cuts battery life roughly in half.
Battery life in real use
Days with your features on.
Why it matters
Quoted '14 days' assumes AOD off, HR sampling low, GPS unused.
What to check
Ask for battery life with always-on display and continuous HR.
Water resistance (ATM / IP)
5 ATM means swim-safe; IP68 means splash and rain only.
Why it matters
Swimmers must have 5 ATM; IP68 watches fail in a pool.
What to check
IP68 is not the same as 5 ATM.
SpO2, ECG and BP claims
Health sensors on the wrist.
Why it matters
Only medically certified ECG is meaningful; wrist BP readings are indicative at best.
What to check
Treat these as trend indicators, never as diagnosis.
Ecosystem & app support
How well it works with your phone.
Why it matters
iPhone users lose call/reply features on many Android-first watches.
What to check
Check notification reply and call support for your phone.
Before you pay
- ✓Decide if you need built-in GPS (outdoor running/cycling) or not.
- ✓Ask for battery life with always-on display and continuous HR enabled.
- ✓Confirm 5 ATM if you swim; IP68 is not enough.
- ✓Check strap size and replaceability for your wrist.
Common traps
- !Buying for '150 sports modes' — most are just timers.
- !Trusting wrist BP or SpO2 as medical readings.
- !Android-first watches paired with iPhones, losing half the features.
Budget bands to GPS running watches and premium smartwatches.