Why your battery shows less than the box says

Your phone’s box says 7100 mAh. You install 3C Battery, charge a few times, and it tells you about 5900 mAh. Is your brand-new battery already tired?

Almost certainly not. The number printed on the box isn’t quite the promise most of us think it is. Here’s the friendly version of a surprisingly interesting story.

One label, two numbers

Battery makers actually measure two different figures:

• Typical capacity: the average of many batteries from the same production line. Some come out a bit above it, some a bit below.
• Rated capacity: the guaranteed minimum. No battery of that model should ever come out below it.

The box, the ad and the website usually show the bigger one, the typical figure. A few brands are kind enough to print both:

Samsung even says it in small print: the advertised number is “the estimated average value considering the deviation in battery capacity among the battery samples”.

Many brands print just one number

Lots of phones only show a single figure, with no hint of which kind it is. Is it the average, the minimum, or the best a lucky unit might reach? You can’t tell from the box.

And every single battery is a little different, even two from the same factory week. Some models even get a different battery depending on the country: the OnePlus Nord CE5, for example, ships with 7100 mAh in India but 5200 mAh in Europe and the UK, under the same name.

So when your phone shows less than the box, it can simply mean the box was showing a generous figure.

Your battery was born before you bought it

There’s one more detail most of us never think about. Your battery wasn’t made the day you opened the box. It was made at a battery factory, then fitted into your phone, shipped across the world, and then it waited in a warehouse and on a store shelf until you came along.

If you bought your phone at launch, the battery was probably only a month or two old. If you picked it up a year or two later, maybe on a nice discount, it may have been waiting six months or more.

The good news: a battery ages much more gently waiting on a shelf than it does in your pocket. Phones leave the factory half-charged, which is exactly how batteries like to rest, and lab tests show a year of resting like that costs only a few percent. Compare that with what our community measures once phones are in daily use: among models released since 2025, the gentlest brands lose around 5 to 6% a year (Samsung 4.6%, Sony 5.3%, Motorola 6.0%), and the fastest around 12 to 15%. So shelf time explains a small part of the gap, but never the whole story.

Buying second-hand? Three quick checks

• Look for the battery’s birth date. Recent Samsung Galaxy phones (S24 and newer, on One UI 7 or later) show it under Settings > Battery > Battery information, along with the charge cycle count and remaining capacity. Recent Pixels show it under Settings > About phone > Battery information, or Settings > Battery > Battery health.
• Check the charge cycles. Each full charge counts as one cycle. A few dozen means it was barely used; several hundred means it worked hard. A brand-new phone can already show a handful, because factories test them before shipping. 3C Battery shows this count too, when your phone reports it.
• Let 3C Battery measure it. After a few charges it tells you what the battery really holds today. That’s the number that matters, whatever the box or the seller says.

What our community sees, brand by brand

This is where you come in! Thanks to everyone sharing anonymous data from 3C Battery, we can compare what batteries actually hold with what was advertised, brand by brand.

How to read this: look at the true health figure. Close to 100% means that brand’s phones really hold about what the box says. A lower figure means the box tends to show a best-case number. It doesn’t mean the batteries are worse, just that the label is more optimistic.

To keep it fair, we only compare recent models here (the years are noted under the charts), so a brand isn’t held back by a few much older phones whose batteries have simply lived a longer life.

We also only compare a few selected brands: the five with the most phones sharing data, so every bar rests on plenty of devices. It is not a ranking of every brand, and the brands left out are listed just above the charts.

A trend is starting to show: some brands land close to their label, others consistently below it. It’s still early, and a brand with only a handful of phones can move a lot as more people join, so please read it as a first glimpse rather than a final verdict.

Why do two apps show different numbers?

Your phone keeps its own running guess of how much charge is inside, often called the charge counter. Some apps show that guess directly. It’s handy, but it’s the phone’s estimate, and even Android’s own documentation says it isn’t guaranteed to be accurate.

3C Battery does something different: it watches what actually flows into the battery each time you charge, and adds it all up. That takes a few charges to settle, but it’s measured rather than guessed. So don’t be surprised if the two disagree. And sometimes the honest number is the less flattering one.

One more fun fact: 100% isn’t always completely full. Most phones show 100% a little early, then keep topping up slowly for a while. 3C Battery keeps counting during that time too.

Getting the most accurate reading

• Keep recording switched on in 3C Battery. While charging, it now takes a reading every minute automatically.
• Let a few charges happen normally. Longer charges help the most, but every charge counts.
• Give it a few days. The estimate gets steadier with each charge.

Thank you!

Every phone that shares its data makes this picture clearer for everyone. If you’d like to help, turn on community sharing in 3C Battery. It’s anonymous, and it’s how we can keep telling these stories with real numbers. Thank you for being part of it!

Sources

• Xiaomi: rated vs typical battery capacity
• Huawei: typical value vs rated (minimum) value
• Samsung: battery capacity footnotes
• Google: Pixel hardware tech specs
• 9to5Google: the Nord CE5’s battery differs by region
• Android Open Source Project: measuring device power
• Battery University: how to store batteries
• SamMobile: Galaxy battery health and cycle count
• 9to5Google: Pixel battery health page