How the grade works
Health is the battery's full charge capacity today divided by its design capacity, the amount it held when it was made. Wear is the part that's gone. A battery at 75% health gives you about three quarters of the runtime it had new.
| Health | Grade | What it means |
|---|---|---|
| 90% and up | Excellent | Close to new. Nothing to do. |
| 80–89% | Good | Normal wear for a battery in regular use. |
| 60–79% | Fair | Runtime is noticeably shorter. Fine if you're usually near an outlet. |
| 40–59% | Worn | Plan a replacement, especially if you work unplugged. |
| Under 40% | Replace | Dell calls a battery below 40% of design capacity significantly degraded. |
The bands above 40% are this tool's own guide for everyday use, not a manufacturer standard.
Why full charge can read higher than design
New batteries often report a full charge capacity a little above their design rating. That's normal. The reading also moves up and down by a few percent with temperature and how the battery has been charged lately, so one report is a snapshot, not a verdict. The capacity history chart is the better guide to the trend.
What the cycle count tells you
One cycle is a full battery's worth of discharge, whether it happens in one go or across several partial uses. Ratings vary by maker. Apple, for example, rates recent MacBook batteries to keep up to 80% of their original capacity at 1,000 cycles. Some batteries don't report a count, and the report shows a dash.
Getting more life from the battery you have
- Keep it cool. Heat wears lithium batteries faster than anything else you control.
- If your laptop stays plugged in most of the time, look in your maker's settings app for a charge limit option.
- Don't store it fully empty for long periods.
Does this work on a Mac?
The report file is a Windows feature. On a Mac, hold Option, click the Apple menu, open System Information and choose Power to see the cycle count. If you know the design and current capacity, enter them under "Enter the numbers" above.