Free tool
MacBook battery health calculator
Enter your battery’s design capacity, capacity now and cycle count to see its health, its wear per cycle and how far it is from Apple’s 80% mark.
Calculate your battery’s health
The example numbers are from the MacBook Air (M1, 2020) Chargeberry was built on. Everything is worked out in your browser; nothing is sent anywhere.
How the calculator works
Health is the capacity now divided by the design capacity. Wear per 100 cycles is how much capacity the battery has lost so far, spread over the cycles it has used. From that, the calculator estimates how many more cycles it may take to reach 80%, the level Apple designs MacBook batteries to keep at their maximum cycle count. It’s a straight-line estimate: real batteries don’t wear evenly, and heat and long stretches at 100% speed it up.
According to Chargeberry’s battery record, the MacBook Air (M1, 2020) it was built on holds 3,643 of its 4,382 mAh design capacity (83.1%) after 353 cycles: about 4.8% of its capacity lost per 100 cycles, with 353 of its 1,000 rated cycles used.
Where to find each number
Open System Information
Hold the Option key, click the Apple menu and choose System Information.
Select Power
In the sidebar, under Hardware, choose Power. Battery Information shows the Cycle Count, Condition and Maximum Capacity.
For the exact mAh, use Terminal
Run
ioreg -rn AppleSmartBattery | grep -E "DesignCapacity|NominalChargeCapacity|CycleCount". DesignCapacity is the battery when new; NominalChargeCapacity is what it holds now, the figure System Settings’ Maximum Capacity is based on. (AppleRawMaxCapacity is the raw reading and usually a little lower.)
How to slow the wear down
Most of a MacBook battery’s wear comes from long stretches at 100% and from heat. Holding the charge around 80% while you’re plugged in, and pausing charging when the battery is hot, slows both. Is it bad to keep a MacBook plugged in? explains why, and Chargeberry does both automatically, and records your battery’s health every day so you can watch the trend.
Questions about battery health numbers
What is a good battery health for a MacBook?
Anything above 80% is within what Apple designs for: MacBook batteries are meant to keep up to 80% of their capacity at their maximum cycle count. A battery at 90% after a few hundred cycles is doing well.
What does Maximum Capacity mean in System Settings?
How much charge the battery can hold now, compared with when it was new. 83% means a full charge holds about 83% of what it did originally, so a full charge lasts about that much less.
How many cycles does a MacBook battery last?
Apple rates modern MacBook batteries for 1,000 cycles. One cycle is using 100% of the battery’s capacity in total, which can take several days of partial use.
Why is my calculated health different from System Settings?
System Settings rounds to a whole percent and Apple may adjust its figure; the raw mAh numbers from ioreg can give a slightly different result. Both are estimates from the battery’s own gauge, and they move a little from day to day.
Can battery health go back up?
Not really. It can wobble by a percent or so as the gauge re-estimates, especially after a full charge, but lost capacity doesn’t come back. What you can do is slow the rest down, mainly by avoiding long stretches at 100% and heat.
