Tech & PC
How long does a phone battery last on a full charge?
Estimated screen-on hours and whether the phone lasts the day, from battery mAh and how you use it — plus after 2 years.
Quick answer
Milliamp-hours are the most quoted and least understood spec on a phone. The number that actually describes your day is screen-on time: how many hours the display can be lit before the battery dies. The bridge between the two is average drain — a modern phone sips roughly 280 mA doing light messaging and browsing, around 380 mA on the social-and-video diet, and 550 mA or more with gaming, navigation and hotspot. Divide usable capacity by drain and you get your hours; that’s the whole calculator.
Estimated screen-on time
~11.2 h
- Does it last the day?
- Yes, with margin
- After 2 years (~85% health)
- ~9.5 h
Estimates assume a modern efficient phone: ~85% of capacity spent during screen-on at the average drain of your profile, the rest on standby. Real numbers swing ±20% with screen brightness, 5G vs Wi-Fi and signal quality — a phone hunting for weak signal drains fast doing nothing. Batteries retain roughly 85% after 2 years of daily charging; the "aged" line shows what your routine will feel like then.
How it works
Two facts worth internalizing before buying or blaming a phone. First, the spec sheet can’t see your signal: a phone clinging to one bar of 5G drains dramatically faster doing nothing than one on solid Wi-Fi — commuters often lose more battery in the train tunnel than watching videos at home. Second, batteries age on a schedule: expect around 85% of original capacity after two years of daily charging, which is exactly when "it used to last all day" complaints begin. If the calculator says your routine barely fits today, in two years it won’t — buy capacity headroom, or budget for a power bank.
Frequently asked questions
How many mAh do I need to get through a day?+
With medium use (about 5 hours of screen between social, video and photos), 4,500-5,000 mAh lasts the day with margin on an efficient phone. Light users are fine from 4,000; heavy users — gaming, navigation, hotspot — should look at 5,500 mAh and up, or the new silicon-carbon batteries pushing 6,000+ mAh in normal-sized phones. Remember these are day-one numbers: subtract ~15% for the phone you’ll own in two years.
What drains a phone battery the most?+
In rough order: the screen at high brightness (halving brightness is the single biggest lever), poor cellular signal (the radio boosts power to compensate), 3D gaming, GPS navigation with screen on, hotspot, and video calls. The background apps everyone blames usually matter less on modern phones — but "battery saver" modes work precisely because they throttle the big items above.
Does charging to 80% really preserve the battery?+
Yes — lithium batteries age fastest at the extremes, full and empty, and when hot. Keeping charge between roughly 20% and 80% can noticeably slow degradation, which is why most phones now offer an 80% charge limit setting. The honest trade-off: you give up 20% of daily capacity today to keep more total capacity in year three. If you change phones every two years, charge to 100% and enjoy it; if you keep them long, the limit pays off.
Is fast charging bad for the battery?+
Much less than feared: modern fast charging front-loads power while the battery is empty and cool, then tapers hard — the harmful combination is heat, not speed itself. Charging under a pillow, in the sun or while gaming does more damage than any 65 W charger. Practical rule: fast charge when you need it, avoid heat always, and don’t obsess — battery replacement after 3-4 years costs less than the mental overhead of babying it daily.
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