Upload a Windows battery report or enter compatible capacity values to calculate the battery's reported health and understand what the result can—and cannot—tell you.
Battery analyzer
Select the Windows report method or enter capacity values manually. Review the source information before relying on the result.
Processing note
Manual values can be calculated in the browser. A selected Windows report is submitted to the site's analysis endpoint.
Battery analyzer
Upload a Windows battery report or enter capacity values manually. Use one method at a time.
Same-unit validation
Do not mix mWh, mAh, percentages, or unlike measurements.
Source values preserved
The calculation should not silently rewrite valid inputs.
Informational result
Consider runtime, behavior, temperature, and physical condition.
Simple by design
The tool keeps the calculation focused and makes its limitations visible rather than hiding them behind a generic score.
Upload the HTML battery report generated by Windows or switch to manual capacity entry.
Use Design Capacity and Full Charge Capacity measured in the same unit.
See the reported health percentage, source values, classification, and important limitations.
Input methods
Windows report
Windows can generate an HTML report containing installed battery information, capacity history, usage data, and estimates when the system reports those values.
Open Command Prompt or Windows Terminal.
Run this command:
powercfg /batteryreportLocate the generated HTML file, review it, and select it in the analyzer.
Manual entry
Use manual entry when the required measurements are already available from the operating system, firmware, or another device utility.
Both values must use the same unit. Do not enter Maximum Capacity percentages as raw Design Capacity values.
Result interpretation
These ranges provide general context. They do not establish battery safety, guaranteed runtime, or a definitive replacement decision.
| Range | Condition | General meaning |
|---|---|---|
| 90% and above | Excellent | Reported full charge capacity remains close to the original design capacity. |
| 80% to 89% | Good | Some capacity loss is present, but reported capacity remains relatively strong. |
| 70% to 79% | Fair | Capacity loss is noticeable and available runtime may be reduced. |
| 60% to 69% | Weak | Reported capacity has declined substantially compared with design capacity. |
| Below 60% | Poor | Reported capacity is significantly below the battery's design capacity. |
Calculation methodology
The calculation compares the battery's reported Full Charge Capacity with its reported Design Capacity.
Formula
Battery Health Percentage = (Full Charge Capacity ÷ Design Capacity) × 100
Design Capacity must be greater than zero. Full Charge Capacity cannot be negative. The source values should remain visible so the calculation can be reviewed.
Accuracy and limitations
Battery context
Rechargeable batteries gradually lose usable capacity through chemical aging. The rate can vary with temperature, charging patterns, workload, storage conditions, battery design, and usage history.
A lower percentage generally means the battery reports that it can hold less energy than its original design capacity. It does not explain every cause of short runtime, charging difficulty, heat, or unexpected shutdowns.
Stop using and charging a battery that is swollen, leaking, punctured, producing an unusual odor, or becoming unusually hot. Follow the manufacturer's safety and service instructions.
Supporting resources
Platform guides
Follow Windows, macOS, and Linux instructions for locating reports, conditions, and compatible capacity values.
Methodology
Review the formula, supported workflows, result handling, data-processing boundaries, and limitations.
Help center
Troubleshoot report uploads, manual values, unusual results, browser problems, and accessibility issues.
Questions and answers
Upload the battery-report.html file created by the Windows powercfg /batteryreport command. Do not rename an unrelated file to use the .html extension.
Yes. Use manual entry when you already have Design Capacity and Full Charge Capacity in the same measurement unit, such as mWh or mAh.
Battery Health Percentage equals Full Charge Capacity divided by Design Capacity, multiplied by 100.
Values above 100% can occur because of calibration, replacement batteries, firmware behavior, or manufacturer reporting. The numeric result should remain visible even when a visual meter is limited to its display width.
No. Capacity percentage is one informational measurement, not a complete hardware diagnosis. Runtime, charging behavior, unexpected shutdowns, temperature, physical condition, and manufacturer guidance should also be considered.
Ready to review your battery
Use a supported Windows report or compatible Design Capacity and Full Charge Capacity values.