The decision is dominated by power versus bandwidth-and-reach. Choose BLE when the device is battery-powered and must last a long time on small periodic data, wearables, sensors, beacons, because BLE sleeps almost all the time and wakes briefly, achieving coin-cell lifetimes of months to years, at the cost of low throughput and short (meters) range. Choose WiFi when you need high bandwidth (streaming, file/firmware transfer), longer range across a building, and especially direct internet connectivity, because a WiFi device joins the LAN as a full IP node and talks straight to the cloud with no intermediary, but the radio draws far more power, so it's for mains-powered, large-battery, or duty-cycled devices. The other pivotal factor is reachability: a BLE-only device can't reach the internet by itself and needs a gateway (typically a phone or hub) to bridge its data, whereas WiFi is internet-direct. So: small periodic data on a tiny battery, phone-tethered → BLE; high data rate or unattended direct-to-cloud → WiFi. Many products combine them (BLE for provisioning/local, WiFi for cloud) or pick a combo chip.
Networking & IoT · Interview question
When would you choose BLE over WiFi, and vice versa?
A strong answer
What a weak answer sounds like
You know the answer. Do you know what gets you dinged?
Pro breaks down the answer most candidates actually give to this question — and the specific reason an interviewer marks it down. It’s the difference between sounding correct and sounding senior, on all 472 questions.
From the lesson
BLE & WiFi for Embedded
Two wireless worlds: BLE's ultra-low-power short-range GATT model (wearables, sensors, phone-tethered) vs WiFi's high-bandwidth, IP-native, internet-direct connectivity, and the power tradeoff.