Battery advice online is 90% folklore. These are the levers that measurably move iPhone battery life, in the order of impact — measured by what actually draws power: the screen, radios hunting for signal, and apps working in the background.
1. See who is actually guilty
Settings → Battery shows per-app usage for the last 24 hours and 10 days, split into on-screen and background. Act on this list, not on vibes: an app with huge “background” time you barely open is suspect number one.
2. Tame Background App Refresh
Settings → General → Background App Refresh. Turn it off for shopping, news and social apps you do not need pre-loaded; leave it on for messaging and mail. This single change is worth visible percentage points a day for most people.
3. Location: “While Using” is your default
Settings → Privacy & Security → Location Services. Set most apps to While Using, games and stores to Never, and keep Precise Location off for apps that only need your city (weather, news). GPS is one of the hungriest radios in the phone.
4. The screen: brightness and Auto-Lock
The display is the top consumer. Turn on Auto-Brightness (Settings → Accessibility → Display & Text Size, at the bottom), set Auto-Lock to 1–2 minutes, and if your iPhone has an OLED screen (X and later, most models), Dark Mode genuinely saves power because black pixels are off.
5. Poor signal drains more than apps
In weak-signal areas the phone boosts radio power hunting for towers. On a long day in a dead zone, Airplane Mode (or Wi-Fi calling) saves more than closing every app. 5G set to “Auto” (Settings → Cellular → Cellular Data Options → Voice & Data) avoids clinging to a weak 5G signal.
6. Push vs fetch for email
Settings → Mail → Accounts → Fetch New Data. Accounts you check manually anyway can fetch hourly or manually instead of Push — meaningful if you carry several busy mailboxes.
7. Low Power Mode is not just for 20%
It trims background activity, mail fetch and visual effects. Turn it on early on long days (add it to Control Center for a one-tap toggle) — using it from 80% stretches a day far more than from 20%.
8. Protect the battery you have
Settings → Battery → Battery Health & Charging: turn on Optimized Charging (and the 80% limit option on newer models if you mostly stay near chargers). Heat is the enemy — do not leave the phone on a sunny dashboard, and skip fast-charging in a hot car. Below ~80% maximum capacity, a battery replacement (Apple or a good shop) makes an old phone feel new for far less than a new phone.
What does not matter much
Force-closing apps from the app switcher — iOS manages them, and reopening from scratch often uses more power. Turning off Wi-Fi/Bluetooth toggles in Control Center (those only disconnect temporarily anyway). And “battery calibration” rituals belong to a previous decade's battery chemistry.