Windows battery report: how to check your laptop’s battery health

You unplug your laptop at 100%, settle down to work, and find yourself looking for a socket much sooner than you expected. A full charge can still be a small amount of stored energy if the battery has lost capacity.

Windows’ battery report helps you compare the battery’s reported full-charge capacity with its original design capacity. That comparison is a useful starting point for investigating wear. Short runtime also depends on how much power the laptop is using, so the percentage alone cannot decide whether you need a replacement.

This guide covers Windows 10 and Windows 11 . Start by creating the report, then use the worked example below to separate three things that are easily confused: charge level, capacity and runtime.

Generate a battery report in Windows 10 or 11

Windows includes a command called powercfg that can write battery information to an HTML file. Microsoft documents the report and its output options in its Powercfg reference . The steps below use its elevated Command Prompt method .

1. Open Start, type Command Prompt, and choose Run as administrator. Approve the Windows prompt on a PC you manage. On a work or school device, ask your IT team if this is restricted.
2. In Command Prompt, enter this command and press Enter:

powercfg /batteryreport /output "%USERPROFILE%\battery-report.html"

When Windows confirms the report was saved, copy the file location it displays. Open File Explorer, paste that location into the address bar and press Enter. The HTML report opens in your browser.

The quoted output path puts the file in the profile folder of the account running the command. Keep the quotation marks: a folder name can contain spaces. Use Command Prompt for this exact example; the %USERPROFILE% notation is different from PowerShell’s environment-variable syntax.

If you cannot find the file

Use the location printed by the command. Running powercfg /batteryreport without an output path saves to the command’s current folder, which is not necessarily Documents or Downloads.

If the command fails, keep the error message and check that you used Command Prompt and retained the quotes. If no battery is listed in a successfully generated report, do not calculate a health percentage from empty values. Check whether Windows recognises the battery and use your laptop maker’s support guidance.

Generating this report does not require deliberately draining the battery. It reports information; it is not a battery-conditioning procedure.

Start with the Installed batteries section

Find Installed batteries near the top of the report. Record DESIGN CAPACITY and FULL CHARGE CAPACITY for the same battery. If the laptop has more than one battery, keep each battery’s figures together.

Microsoft’s battery firmware documentation distinguishes the original capacity, the estimated full-charge capacity and the changing remaining-capacity reading. Windows receives these figures through the battery subsystem; they are reported information, rather than an independent laboratory measurement.

Capacity is commonly shown in mWh, meaning milliwatt-hours. Divide by 1,000 to express the same energy in Wh, or watt-hours. Thus, 60,000 mWh is 60 Wh. Keep both values in the same units before comparing them.

Worked example: 75% capacity can still show 100% charged

Suppose a report shows these illustrative figures:

• Design capacity: 60,000 mWh.
• Full charge capacity: 45,000 mWh.

Calculate the proportion of design capacity still reported:

45,000 ÷ 60,000 × 100 = 75%.

The battery is reporting three-quarters of its design capacity, a 25% shortfall. When charged to its present maximum of 45,000 mWh, it can still show 100% charged.

BAPCo’s 2021 paper on notebook battery degradation explains the capacity comparison and the corresponding capacity-loss calculation. These example numbers are ours for illustration; they are not results from a tested laptop.

Now suppose the same battery has 22,500 mWh remaining. That is half of its present full-charge capacity:

22,500 ÷ 45,000 × 100 = 50% charge.

The comparison below puts all three amounts on the same scale.

*Illustrative values, not measured results. The 50% charge level is half of the current 45 Wh capacity; the capacity comparison is 45 Wh against the original 60 Wh.*

This is why the number beside the battery icon cannot tell you how much capacity the battery has retained. You need both capacity readings to make that comparison.

The 75% figure is also not a prediction of how many months the battery has left. It is a comparison of reported capacity at the time of the report.

Read the history before judging one number

Next, look through Battery capacity history. Where records are available, compare the full-charge figures across several dates.

A sustained decline gives useful context for a low reading. One unusual entry is a reason to investigate further before buying a battery. Save the report, note its date, and compare it with another report after ordinary use. Keep track of any battery replacement so you do not mistake a change of hardware for a sudden recovery.

Microsoft describes the report as including recorded usage, capacity changes and history-based battery-life estimates . Treat it as the history Windows has available, not a guaranteed record of everything that has happened to the battery.

Two practical rules help:

• A missing value is not zero. If a capacity or cycle-count field is blank or shows a dash, leave it out of your calculation.
• Keep observations separate from explanations. “Full-charge capacity is lower than last month” is an observation. “A particular update damaged the battery” requires evidence the report alone does not supply.

For a used laptop, a fresh report is more useful than a seller’s screenshot of the taskbar at 100%. Ask to see the capacity readings and the machine running unplugged under a task similar to your own. Neither check guarantees future reliability, but together they answer more of your actual question.

Why capacity does not translate directly into hours

Stored energy is only one part of runtime. The other is the rate at which the laptop uses it.

For a deliberately simplified example, assume the battery can deliver 45 Wh of usable energy and power use stays constant:

These are calculations, not measured performance. Actual use changes from moment to moment, and the operating conditions and low-battery cutoff affect what is usable. The example shows why the same battery can last very different lengths of time under different workloads.

Screen brightness, processor activity and other settings influence consumption. Dell’s Power Manager guide , for example, identifies processor power, screen brightness and keyboard illumination as controls that affect battery use.

This also explains how to read Battery life estimates. An estimate based on the PC’s recorded use is not a promise for a different task. A quiet reading session and a demanding game are poor comparisons for judging whether capacity changed.

Make one comparison you can repeat

Choose an ordinary task you actually need the laptop for, such as editing a document or watching the same local video. Begin at a similar charge level, use the same brightness and power setting, and note the start and finish times.

You do not need to run it to empty. A fixed observation period lets you compare charge loss while keeping the task and settings reasonably consistent.

For example, record: “30 minutes editing the same document, brightness unchanged, battery fell from 80% to 72%.” Repeat the conditions another day. This is a practical comparison, not a laboratory capacity test, but it gives a support technician more to work with than “the battery seems bad”.

If you change several settings, install updates and switch workloads between observations, record those differences too. Otherwise, you can easily attribute a runtime change to the wrong cause.

Decide what to check next

Use the report to choose the next investigation.

There is no reason to treat our example’s 75% as a universal replacement deadline. The practical question is whether the laptop reliably lasts long enough for your use, alongside what its manufacturer’s checks report.

Dell’s battery-health descriptions illustrate the distinction: a battery can still charge normally while its operating time declines. Its categories apply to supported Dell systems; other manufacturers have their own tools and criteria.

If the battery or casing is visibly swelling, stop using the laptop and contact the manufacturer for handling and replacement guidance. A favourable capacity percentage cannot establish physical safety. Dell’s swollen-battery guidance treats swelling as a separate problem requiring action.

Does stopping at 80% mean the battery has 80% health?

Not necessarily. A charging limit can deliberately stop charging below 100%. That setting and the capacity ratio answer different questions.

For example, Dell documents a **Primarily AC** mode that lowers the charging threshold on supported systems. Check your own laptop’s charging settings and manual if it consistently stops at a particular percentage. Do not assume the limit exists on every model, or disable a setting without understanding why it was enabled.

To assess capacity, return to the report’s design and full-charge figures. To assess how long you can work away from a socket, compare actual use under similar conditions.

Keep the dated report, the two capacity readings and a short note about the runtime problem. Those three pieces of information give you a practical basis for deciding whether to adjust usage, seek a diagnosis or arrange a replacement.

Sources

• Microsoft: Powercfg command-line options , updated 15 December 2021.
• Microsoft: Battery-life reports and Modern Standby diagnostics , updated 5 November 2020.
• Microsoft: ACPI battery and power subsystem firmware implementation , updated 11 January 2022.
• Tobii Dynavox: Checking battery health on a Windows device , 9 August 2022. Used for the Windows 10/11 reporting workflow.
• BAPCo: Li-ion Battery Degradation in Notebook Computers , Shane Branch, Intel Corporation; published 24 February 2021 .
• Dell: Command | Power Manager User Guide , January 2017, especially pages 6–7 and 13.
• Dell: Handling swollen Lithium-ion batteries , July 2019.