Give us your battery information
On Windows, you can upload the battery-report.html file. You can also enter your battery capacity numbers manually.
Simple battery capacity check
Check your laptop battery health
Find out how much of your battery's original capacity is currently being reported — with a result explained in simple language.
Upload a supported Windows battery report, or enter two battery capacity values manually. No technical knowledge is required to understand the result.
Windows
Upload battery-report.html
Manual
Enter two matching values
Result
Percentage explained simply
What are we measuring?
How much capacity is your battery reporting now?
We compare the battery's reported current full-charge capacity with its reported design capacity.
Calculation
Current capacity ÷ Original capacity
Battery checker
Check your battery
Choose the easiest option for you. If you have a Windows battery report, upload it. If you already know your battery capacity values, enter them manually.
Battery analyzer
Choose how to provide battery capacity data
Upload a Windows battery report or enter capacity values manually. Use one method at a time.
Processing information
Manual values can be calculated in your browser. A selected Windows battery report is submitted to the site's analysis endpoint for processing.
How it works
Three simple steps
You do not need to understand battery engineering. Just provide the battery information available on your device.
We compare the numbers
The tool compares the battery's reported current capacity with its reported original design capacity.
Read the simple result
You get a percentage plus a plain-language explanation of what that number means.
Windows
Have a Windows laptop?
Windows can create a battery report containing the capacity information needed by the analyzer. You can create the report yourself in a few steps.
Open Windows Command Prompt with the appropriate permissions.
Run the Windows battery report command.
Find the generated battery-report.html file and upload it above.
Windows battery report
The command used by Windows is:
powercfg /batteryreportThe exact report location can vary. Windows normally tells you where the generated file was saved.
Manual option
Already have your battery numbers?
You can check your battery without uploading a report. You only need two capacity values from a trusted source.
Design Capacity
What the battery was designed to hold
This is the battery capacity reported as its design or original capacity.
Full Charge Capacity
What the battery currently reports
This is the battery's reported capacity when fully charged.
One important rule
Both values must use the same unit. For example, do not enter one value in mWh and the other in Wh.
For platform-specific instructions, see our platform guides.
Your result
What does the percentage mean?
The percentage is a simple comparison between your battery's reported current capacity and the capacity it was designed to have.
| Reported capacity | General interpretation |
|---|---|
| 90%+ | Close to design capacity |
| 80–89% | Moderate reported capacity loss |
| 70–79% | Noticeable reported capacity loss |
| 60–69% | Substantial reported capacity loss |
| Below 60% | Significant reported capacity loss |
Important: These are descriptive ranges, not manufacturer replacement thresholds. A percentage alone does not tell you whether a battery is safe, how long it will last, or whether it needs to be replaced.
An easy way to think about it
If your result is 90%, the battery is reporting about 90% of the capacity it was designed to have. It does not mean the battery will always provide 90% of a particular laptop's original runtime.
Important context
What this percentage cannot tell you
Battery capacity is useful information, but it is only one part of understanding a battery.
It does not predict exact runtime
Actual battery life depends on things such as what you are doing, brightness, applications, power settings, and hardware.
It is not a safety test
A percentage cannot determine whether a physically damaged, swollen, leaking, or otherwise unsafe battery is safe to use.
It does not diagnose every problem
Charging faults, overheating, sudden shutdowns, calibration issues, firmware behavior, and other hardware problems can have different causes.
It does not guarantee battery lifespan
The number describes reported capacity at the time of the measurement. It does not predict exactly how long the battery will continue to work.
It can change over time
Battery reports and device software can provide updated capacity values as the battery ages or its reported values change.
It is not a replacement decision
If you are deciding whether to replace a battery, consider the battery's symptoms, device guidance, warranty information, and professional advice where appropriate.
Battery basics
Why does battery capacity decrease?
Rechargeable batteries naturally change as they are used and age.
A rechargeable laptop battery is made from cells that store and release energy. Over time, normal use and chemical aging can reduce the amount of energy the battery can store compared with when it was new.
That is why a battery may eventually report a lower Full Charge Capacity than its original Design Capacity.
Our calculator focuses on that reported capacity relationship. It does not attempt to turn one percentage into a complete diagnosis of the battery or laptop.
Safety comes first
If a battery is swollen, leaking, punctured, unusually hot, or has an unusual smell, do not rely on a battery percentage to decide whether it is safe. Follow the device manufacturer's safety guidance and seek appropriate professional help.
Our method
A simple calculation you can understand
The core calculation uses two reported capacity values. We keep the calculation visible instead of hiding it behind a score.
Formula
Reported capacity % = (Full Charge Capacity ÷ Design Capacity) × 100Design Capacity
The reported capacity the battery was designed to have.
Full Charge Capacity
The reported capacity available when the battery is fully charged.
What we check
- The Design Capacity must be greater than zero.
- The capacity values need to be compatible and use the same unit when entered manually.
- Reported values are preserved rather than silently changed to fit a preferred range.
- A result above 100% can remain visible when the reported Full Charge Capacity is higher than Design Capacity.
Platform guides
Need help finding your battery information?
Our guides explain where to find compatible battery information on different operating systems and devices.
Windows
Battery report upload
Create the Windows battery report and upload the generated HTML file to the analyzer.
Windows instructionsmacOS
Find compatible capacity information
Follow the platform guidance for finding compatible battery capacity values that can be entered manually.
macOS instructionsLinux
Find compatible capacity information
Use the platform guidance to locate compatible battery capacity values for manual entry.
Linux instructionsWindows battery-report.html upload is the dedicated report-upload workflow. macOS and Linux guidance should be understood as help for finding compatible capacity information for manual entry.
FAQ
Common questions
Here are straightforward answers to the questions people usually have about the battery capacity result.
What battery report should I upload?
On Windows, upload the battery-report.html file created by the Windows
powercfg /batteryreport command. The report should contain the battery capacity information needed by the analyzer.Can I check my battery without uploading a report?
Yes. If you already know your battery's Design Capacity and Full Charge Capacity, you can enter those two values manually. Use values from a trusted operating-system, firmware, or device utility source and make sure both values use the same unit.
How is the battery percentage calculated?
We divide Full Charge Capacity by Design Capacity and multiply the result by 100.
Full Charge Capacity ÷ Design Capacity × 100Why can my result be above 100%?
This can happen when the reported Full Charge Capacity is higher than the reported Design Capacity. The calculator shows the reported values rather than changing them to force the result below 100%.
Does a low percentage automatically mean I need a new battery?
No. The percentage describes the relationship between reported Full Charge Capacity and Design Capacity. It does not by itself diagnose battery safety, remaining lifespan, charging problems, overheating, or whether a battery must be replaced.
Learn more
Battery guides and information
If you want to understand the result, troubleshoot a battery, or learn how the calculator works, these resources are a good place to start.
Guides
Find your battery information
Step-by-step help for finding compatible battery information on supported platforms.
Browse guides →Methodology
How the calculator works
Learn how the calculation works, how values are handled, and what the result cannot determine.
Read the methodology →Help
Battery questions answered
Clear answers to common questions about battery capacity, reports, percentages, and results.
Read the FAQs →