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Check your phone’s built-in battery-health screen or manufacturer diagnostics first. iPhone and some newer Pixel models show an estimated remaining capacity; Samsung Galaxy diagnostics report battery status. Any percentage is an estimate, not a direct lab measurement of the battery’s exact capacity.
Choose the check for your phone
| Phone | Where to check | What it reports |
|---|---|---|
| iPhone 15 and later with iOS 17.4 or later | Settings > Battery > Battery Health | Battery health and maximum-capacity estimate, cycle count, manufacture date, first-use date, and any replacement recommendation. |
| iPhone 11, 12, 13, or 14 | Settings > Battery > Battery Health & Charging | Maximum-capacity estimate and peak-performance information. |
| Pixel 8a and later | Settings > Battery > Battery health; for cycle count and dates, Settings > About phone > Battery information | Battery-health status and estimated capacity, plus cycle count and dates in Battery information. |
| Other supported Pixel models | Settings > Battery > Battery Diagnostics | A diagnostic, but not necessarily a battery-health percentage. Google says Pixel 6a, Pixel 7 family, and Pixel 8/8 Pro do not show Battery health status. |
| Samsung Galaxy | Samsung Members > Phone diagnostics > Battery status; Device care diagnostics may also be available | A battery-status diagnostic. A numeric remaining-capacity percentage is not promised for every Galaxy model. |
For detailed model-specific guidance, see Apple’s iPhone battery and performance guidance, Google’s Pixel battery guidance, and Samsung’s Galaxy diagnostics instructions. Menus and available tests can vary by model and software version.
How to interpret a battery-health percentage
Battery health usually compares the battery’s estimated remaining capacity with its capacity when new. It is different from the charge percentage in the status bar: that shows how much charge is available now, not how much the battery can hold when full.
Google says Pixel capacity is estimated by the battery’s fuel gauge and that initial battery-health values are based on lab results that may differ from the battery’s actual state. Apple also notes that maximum capacity depends on use and charging. Treat a displayed percentage as an estimate rather than an exact measurement of usable capacity. See Google’s explanation of Pixel battery estimates and Apple’s battery guidance.
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What cycle count can—and cannot—tell you
A charge cycle represents cumulative use equivalent to 100% of the battery’s capacity; it does not have to happen in one discharge. For example, using half the battery on two occasions adds up to one cycle. Cycle count helps put a health estimate in context, but it is not a capacity reading. Temperature, charging habits, usage, and variation between batteries affect how quickly a battery ages.
| Model group | Manufacturer design guidance |
|---|---|
| iPhone 14 and earlier | Designed to retain 80% of original capacity after 500 complete charge cycles under ideal conditions, according to Apple. |
| iPhone 15 and later | Designed to retain 80% of original capacity after 1,000 complete charge cycles under ideal conditions, according to Apple. |
| Pixel 3 through Pixel 8 Pro, and Pixel Fold | Designed to retain at least 80% of initial capacity for about 800 cycles under recommended charging conditions, according to Google. |
| Pixel 8a and later | Designed to retain at least 80% of initial capacity for about 1,000 cycles under recommended charging conditions, according to Google. |
These are model-family design targets, not guarantees for an individual phone. Check the current manufacturer guidance for your exact model: Apple and Google.
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If your phone does not show a percentage
Battery-health menus differ across manufacturers, models, and software versions. Run the diagnostic provided for your exact phone or consult its manufacturer’s support guidance. A diagnostic may tell you whether the battery status is normal or needs attention without giving a capacity number.
For Pixel, Battery Diagnostics is available on Pixel 6 and later, including Pixel Fold, but the Battery health screen is narrower in availability: Google identifies Pixel 8a and later as the models that show it, and says Pixel 6a, Pixel 7 family, and Pixel 8/8 Pro do not indicate Battery health status. Samsung’s diagnostic likewise provides the status its supported test reports, not a guaranteed mAh or percentage value. Do not assume a generic Android code, app, or ADB method works across phones; Android’s system-health documentation describes system information, not a universal consumer battery-capacity test. See Google’s Pixel battery troubleshooting guidance and the Android Open Source Project system-health documentation.
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Why a charger or charging meter is not a capacity test
A charger or meter can report charging power or energy supplied during a session. That does not establish how much energy the installed battery can still store when fully charged. Likewise, the current charge percentage is not a health percentage. Use the phone’s own estimate or diagnostic rather than comparing these different measurements as if they were interchangeable.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When to seek battery service
Follow the manufacturer’s recommendation for the exact device. Google advises considering Pixel battery replacement when the battery-health status is Reduced or the model’s rated cycle threshold has been reached. Apple provides support options when replacement is recommended and advises using Apple or an authorized service provider for built-in battery service. See Google’s Pixel battery guidance, Google’s battery troubleshooting guidance, and Apple’s battery service information.
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- Precise Power Bank Capacity Testing: Accurately test power bank capacity either by direct load testing or by calculation. To determine capacity, charge the power bank fully and divide the Wh reading by battery voltage (e.g., 35Wh ÷ 3.7V = 9.46Ah or 9460mAh), offering reliable insight into actual capacity.
If a battery has been replaced, check the phone’s current warning and service guidance before relying on its metrics. Apple’s June 2024 environmental report said it planned to show some metrics with a warning that Apple could not verify them when calibration data for third-party parts was unavailable; that report is historical context, not a guarantee of what a current phone will display. Apple’s June 2024 report.
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