The belief that switching off wireless connections can save battery dates back to when Bluetooth and Wi-Fi were significant power drains. Initially, when pairing with a new device, Bluetooth had to perform an “inquiry scan,” which consumed more energy.

However, once paired, Bluetooth shifts to “page mode,” where it simply waits for familiar devices to reconnect - causing almost no noticeable battery drain.

From Bluetooth 4.0 onward, and especially with Bluetooth 5.3 used in most modern smartphones, energy consumption is drastically reduced, even when streaming music, with power usage down to just 5–8%.

With Bluetooth Low Energy (BLE) devices such as smartwatches, power drain is even lower - only about 1–3% over 24 hours. Therefore, turning off Bluetooth when not in use barely makes any difference in overall battery life.

On iPhones, Bluetooth that’s turned on but not connected to any device draws virtually zero power. The chip remains idle and barely uses electricity. Even when connected to a hands-free device, it only consumes around 2.5 mW.

To put it into perspective, the iPhone 8 has a battery capacity of roughly 6,900 mWh. If Bluetooth were the only thing running, it would take almost 2,800 hours - about three months - to drain the battery.

Even with devices requiring more power, such as those demanding up to 10 mW, Bluetooth is never the main culprit behind rapid battery loss.

So, if your phone’s battery life is underwhelming, the reason certainly isn’t Bluetooth or Wi-Fi.

Wi-Fi, on the other hand, presents a slightly different case. It is designed for maximum stability. In areas with weak signals, phones constantly switch between 4G and 5G, consuming more battery.

When Wi-Fi is turned on, a stable connection prevents this back-and-forth switching, potentially saving power in weak mobile signal areas.

Furthermore, modern operating systems limit how often apps can scan for Wi-Fi. On Android 9, background apps are allowed only one scan every 30 minutes, making power usage negligible.

According to Apple’s official community site, Wi-Fi on iPhones and iPads automatically turns off in sleep mode - unless the device is charging - so manually disabling it has little benefit.

When not connected to a network, Wi-Fi scans every 15 seconds using only the receiver, which draws less than 1 mW - an amount too small to even measure.

When connected to a network, Wi-Fi consumes only around 30 mW, regardless of whether data is being transmitted. By comparison, mobile data uses between 50 and 500 mW, depending on signal strength.

This means that, in almost every usage scenario, Wi-Fi consumes less power than 4G or 5G - especially when transferring data continuously.

So, turning off Wi-Fi not only fails to save energy, but can actually increase battery drain as the device switches to more power-hungry mobile data.

The real ways to extend battery life include enabling Low Power Mode, reducing screen brightness, or limiting background app activity. These steps genuinely improve battery performance - especially when you're trying to stretch usage time.

Disabling Bluetooth and Wi-Fi, from a battery-saving standpoint, offers minimal benefit. In fact, in some cases, leaving Wi-Fi on can save power when cellular coverage is weak.

That said, from a security perspective, the situation changes. While power savings are marginal, turning off Bluetooth and Wi-Fi when not in use may reduce the risk of device tracking, vulnerability exploits, or malicious scans.

Therefore, the most balanced advice is: if you want to optimize battery life, focus on app management, screen brightness, and power-saving features. But if you prioritize data security, then it’s wise to switch off Bluetooth and Wi-Fi when not needed.

Du Lam