About the site

About CheckBatteryHealth

CheckBatteryHealth is a web-based resource for understanding reported laptop battery capacity. The site provides a battery analyzer, practical platform guides, and explanations of common battery terms and measurements.

The analyzer can calculate a capacity percentage from compatible battery information. The surrounding guides explain how to find that information, how to interpret it, and when a capacity percentage is not enough to understand a battery problem.

Open battery analyzer See how it works

What we provide

Practical battery information without unnecessary complexity

Laptop operating systems can expose technical battery information such as Design Capacity, Full Charge Capacity, cycle count, recent usage, and capacity history. Those values are useful, but their meaning is not always obvious.

CheckBatteryHealth brings the relevant information together into practical workflows. Users can calculate reported capacity, learn where battery information comes from, and read supporting explanations before deciding what a result means for their device.

The site also covers related topics such as charging, battery runtime, temperature, replacement, storage, troubleshooting, and platform-specific battery checks.

Browse the battery guides

Why it exists

Built around a simple battery question

Battery information is often available on a laptop, but a list of technical numbers does not automatically explain what those numbers mean.

CheckBatteryHealth was created to make the basic capacity calculation easier to understand while keeping the source values, formula, assumptions, and limitations visible.

The project focuses on reported battery information. It does not claim to perform a physical battery test, laboratory measurement, or complete hardware diagnosis.

How information is presented

Clear calculations, practical context, and honest limitations

Show the calculation

The site explains which capacity values are used and shows the formula instead of presenting an unexplained battery score.

Explain the result carefully

A capacity percentage is presented as a measurement of reported capacity, not as a complete diagnosis of battery safety, electronics, or remaining lifespan.

Give platform-specific instructions

Guides explain where battery information can be found on supported platforms and distinguish Windows report data from manually entered values.

State important limitations

Battery capacity is only one part of battery condition. The site explains situations where manufacturer diagnostics, physical inspection, or other information is more appropriate.

Methodology

How the battery capacity percentage is calculated

The core calculation compares the current reported Full Charge Capacity with the reported Design Capacity.

Formula

Battery Health Percentage = (Full Charge Capacity ÷ Design Capacity) × 100

Both capacity values need to use the same unit. For example, mWh should be compared with mWh, and mAh should be compared with mAh. A percentage is not itself a capacity measurement.

The calculation is intentionally simple and transparent so that users can reproduce the result from the original capacity values.

Interpreting results

A percentage is useful, but it is not the whole diagnosis

Reported capacity can help describe how a battery's current reported capacity compares with its original reported capacity. It does not directly measure runtime, electrical safety, or every aspect of battery condition.

Results above 100% are not automatically errors. They can occur because of calibration differences, replacement batteries, firmware behavior, or differences in how capacity is reported.

Where a device shows unusual behavior, manufacturer diagnostics and the device-specific documentation may provide information that a capacity calculation cannot.

Read the detailed methodology

Analyzer workflows

Two ways to provide battery information

The analyzer supports different ways of providing battery information. The processing path depends on which workflow is used.

Windows battery report

Windows can generate a battery-report.html file containing information such as installed batteries, Design Capacity, Full Charge Capacity, usage history, and capacity history when those values are available.

When a user submits a Windows battery report through the analyzer, the selected file is sent to the site's analysis endpoint for processing. The Windows upload workflow is therefore not local-only.

Manual capacity calculation

Users can enter Design Capacity and Full Charge Capacity directly when both values are available and expressed in the same unit.

The calculation uses the supplied values as entered. Values that are missing, invalid, or expressed in incompatible units should not be silently converted or guessed.

Use the battery analyzer Read platform guides

Limitations

What a capacity result cannot determine

The calculation depends on capacity values reported by the operating system, firmware, battery controller, device driver, or another source used by the user.
A capacity percentage does not diagnose every charging, electrical, thermal, firmware, calibration, or physical battery problem.
Values can sometimes exceed 100% because of calibration differences, replacement batteries, firmware behavior, or manufacturer reporting differences.
Battery runtime depends on many factors, including workload, display brightness, background activity, temperature, power settings, applications, and device configuration.
A swollen, leaking, punctured, damaged, or unusually hot battery should be treated as a physical safety issue rather than evaluated only by an online percentage.

If a battery appears swollen, leaking, punctured, damaged, or unusually hot, stop relying on an online percentage and follow the device or battery manufacturer's safety guidance.

Data transparency

How analyzer information is handled

The analyzer does not use the same processing path for every workflow. Manual capacity entry and Windows report submission are handled differently.

Manual calculation

Users can enter Design Capacity and Full Charge Capacity into the interactive calculator without uploading a battery report.

Windows report

A selected Windows battery report is submitted to the site's analysis endpoint for processing. The Windows report workflow is therefore not a local-only process.

Privacy information

The Privacy Policy explains what information may be handled by the analyzer and its supporting infrastructure, including relevant processing, retention, logging, sharing, and deletion practices where applicable.

Read the Privacy Policy Contact us

Privacy information should match the actual analyzer, API, hosting, logging, analytics, advertising, and consent implementation. The site's Privacy Policy is the primary reference for current data-handling details.

Resources and support

Continue with the information you need

CheckBatteryHealth includes practical guides and support information for users who want to understand a result, find battery information, or troubleshoot a battery-related issue.