Laptop battery and power, worked out

Read the battery.Size the charger.

Your laptop already keeps a record of how worn its battery is. Open that report here and see it in plain words: how much of its original capacity is left, how many cycles it has used and how long a charge lasts. Then check whether a USB-C charger or power bank will keep up, and whether the power bank can fly with you.

01Read my battery report 02Check a charger or power bank

Laptop Card Plus $1.95 a month or $19.50 a year Free during preview What it buys

Example resultWindows battery report

79.5%

of design capacity

Worn

Design: 57,000 mWh
Now: 45,315 mWh
Cycles: 312 of a rated 1,000
Runtime: About 3.8 hours at 12 W

Read from a Windows battery report in the browser. The report itself never left the laptop.

Three tools

Everything you need to judge a laptop battery.

01 Reader

Read the battery

The Battery Report Reader opens the report your laptop already makes: from Windows it reads the design capacity, full charge capacity and cycle count; from Linux upower the same figures or the capacity percentage; from a Mac the Maximum Capacity percentage and cycle count (older Intel Macs show no Maximum Capacity, so only the cycle count is read). The report stays on your device; only the numbers are sent, when you ask for a result.

Open the reader

02 Power

Size the charger

The Charger and Power Desk compares a USB-C charger or power bank with your laptop's own charger, works out a power bank's watt-hours, and shows the FAA carry-on rule that applies to it.

Check a charger

03 Card

Keep the record

A private Laptop Card keeps dated readings for each laptop, so you can see how fast a battery is wearing and decide when a replacement is worth it. No account, no email.

Start a Laptop Card

Before you start

How to get the report

Windows

powercfg /batteryreport

Open Command Prompt and run powercfg /batteryreport. It saves battery-report.html in the folder shown; open that file on the reader.

Mac

Option + Apple menu
System Information
Power

Hold Option, open the Apple menu, choose System Information, then Power. Copy the Battery Information text and paste it on the reader.

Linux

upower -i $(upower -e | grep BAT)

Run upower -i $(upower -e | grep BAT) in a terminal and paste the output on the reader.

Charger check

Measured against your own charger.

Too weak under 60% of its watts
Slower 60% to under 100%
Enough 100% or more

This site's rule of thumb; your laptop decides. See Sources.

Flying with a power bank

The FAA carry-on rule, by watt-hours.

Up to 100 Wh carry-on
101 to 160 Wh airline approval, up to two spares
Over 160 Wh beyond the passenger limits

Summary of FAA PackSafe; airlines may set stricter rules.

Pricing

The tools are free. Laptop Card Plus is $1.95 a month.

Free

1 laptop · 3 readings

Battery Report Reader for Windows, Mac and Linux reports, read in your browser (up to 100 results a day)
Charger and Power Desk: USB-C charger and power bank check, FAA carry-on rules, charges per bank
A private Laptop Card with 1 laptop and up to 3 battery readings

Laptop Card Plus

$1.95 a month

or $19.50 a year (two months free)

10 laptops · 200 readings each

Up to 10 laptops on one card: the family's, or a small office's
Up to 200 dated readings per laptop, so you can see how fast each battery is wearing
Wear trend chart per laptop, a printable battery sheet for every laptop, and CSV download

Free during preview: every Plus feature is on for everyone and nothing is charged.

Laptop Services does no repairs and sells no batteries or parts. It never connects to your computer and nobody from it will ever ask for remote access.