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Check your phone’s built-in battery health screen or manufacturer diagnostic first. It may show a health percentage or estimated capacity, but it often does not give a direct measurement of the battery’s current capacity in mAh. To convert a published mAh rating to watt-hours (Wh), you also need the battery’s nominal voltage: Wh = (mAh ÷ 1,000) × voltage.
Check the battery information on your phone
Menu names and available readings depend on the phone model and software version. A battery health percentage usually compares the battery’s capacity with its condition when new; it is not automatically an absolute mAh reading.
iPhone
- iPhone 15 and later with iOS 17.4 or later: Open Settings → Battery → Battery Health. Apple says this screen can show maximum capacity, cycle count, manufacture date, first-use date, and whether replacement is recommended. See Apple’s instructions for iPhone 11 and later.
- iPhone 11, 12, 13, and 14: Open Settings → Battery → Battery Health & Charging. The exact information shown depends on model and software.
Apple defines maximum capacity as the device battery’s capacity relative to when it was new, not as a direct mAh readout. If the phone says it cannot verify the battery, its battery details may not be accurate; consult Apple’s battery and performance guidance rather than treating the displayed value as definitive.
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Google Pixel
On Pixel 8a and later, go to Settings → Battery → Battery health → Battery capacity to see the estimated capacity. Google says battery health is available only on Pixel 8a and later; its documentation says Pixel 6a, Pixel 7, Pixel 7 Pro, Pixel 7a, Pixel 8, and Pixel 8 Pro do not indicate battery health status. The estimate compares remaining capacity with original capacity, and Google cautions that initial health values are based on lab results and may differ from the battery’s actual state. Details are in Google’s Pixel battery help.
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Samsung Galaxy
Open Samsung Members → Support → Phone diagnostics, then check or test battery status. Interface labels and availability can vary by app and device version. Samsung documents a battery-status diagnostic, not a universal remaining mAh or Wh measurement. Its battery support guidance recommends service-center evaluation if the phone shuts down unexpectedly often or battery life has noticeably declined.
Other Android phones
Check the manufacturer’s settings and support instructions for your exact model. Android does not have one universal battery-health menu or a guaranteed numerical capacity reading. If you need the original nominal mAh and voltage, look for the manufacturer’s specification or battery label.
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Convert a battery rating from mAh to Wh
mAh measures electric charge capacity. Wh measures energy and accounts for voltage, so mAh alone is not enough to calculate Wh. Convert mAh to amp-hours by dividing by 1,000, then multiply by the battery’s nominal voltage:
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For example, a hypothetical 5,000 mAh battery at a nominal 3.85 V works out to 19.25 Wh. Those values are assumed for the example, not specifications for a particular phone.
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- Multi-Device Compatibility & Safety Features: This battery capacity tester supports discharge aging tests for a wide range of devices, including chargers, cables, power banks, batteries, and power adapters. It has intelligent safety protection such as overload, overcurrent and high temperature protection, real-time monitoring of status makes it safe and reliable.
- Four Discharge Modes & App Compatibility: The USB load tester supports constant current, constant power, constant resistance, and constant voltage modes. It is compatible with Android and iOS apps, as well as PC BT and wired connections, providing versatile testing options.
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A published illustration from iFixit uses a FixHub battery pack, not a phone: 5,200 mAh × 10.8 V ÷ 1,000 = 56.16 Wh. See iFixit’s explanation of mAh and battery capacity.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What battery health and capacity numbers tell you
A phone’s health estimate, its original rated capacity, and its current absolute capacity answer different questions. A health percentage describes capacity relative to when new; the original mAh rating describes charge capacity when the battery was new; Wh expresses energy using both capacity and voltage. A health percentage cannot be turned into a reliable current mAh figure unless the original capacity is known and the percentage is a suitable estimate for that purpose.
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- Button Function: 1.Click the button once to switch screens in a cyclical manner; 2.Double-click the button to rotate the displayed content; 3.Press and hold the button (3 seconds): Clear all capacity, amount of electricity, and time.
Specifications also may distinguish a typical capacity from a rated or minimum value. Huawei explains that typical capacity is the average actual capacity for a production batch, while rated capacity is the minimum under IEC 61960 test conditions. Preserve that distinction when comparing published figures; see Huawei’s explanation of typical and rated capacity.
When comparing energy across batteries with different voltages, Wh is more useful than mAh alone: a larger mAh figure does not necessarily mean more energy. If comparing mAh figures, check that the voltage assumptions are comparable.
When to seek service
Use the manufacturer’s model- and region-specific service options if the phone reports reduced health or recommends replacement. A diagnostic can indicate a concern without providing a direct measurement of remaining mAh or Wh. Unexpected shutdowns or a noticeable decline in battery life are reasons to consult the maker’s support guidance.
Cycle-life figures are manufacturer guidance, not guarantees for each individual device. Apple says iPhone 14 models and earlier are designed to retain 80% of original capacity after 500 complete charge cycles under ideal conditions, and iPhone 15 models after 1,000 complete cycles under ideal conditions; actual capacity depends on regular use and charging. Google says Pixel 3 through Pixel 8 Pro and Pixel Fold can retain up to 80% capacity for about 800 charge cycles, and Pixel 8a and later for about 1,000; on supported models, Google labels remaining capacity below 80% as “Reduced.” These model-specific statements and qualifications are documented by Apple and Google.
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