Apple MacBook Air 15" (M4, 2025) battery capacity & backup time

Apple's spec page lists 66.5 Wh for the Apple MacBook Air 15" (M4, 2025) (built-in 66.5 Wh). The capacity of yours is printed on the battery label and shown as "design capacity" in a Windows battery report.

Estimated for a new 66.5 Wh pack at about 60% brightness: 15 h 50 min of browsing or office work, 9 h of video calls and 3 h 30 min of gaming. These are estimates from typical power draw, not measurements.

On a used battery at 80% health with the 66.5 Wh pack, office work runs for about 12 h 40 min, so a 2-hour outage is covered for the laptop itself. Your Wi-Fi router still needs a mini UPS; the load-shedding calculator works out both.

Replace it when the full-charge capacity falls to about 60-70% of the design capacity (around 43 Wh on a 66.5 Wh pack), when the laptop shuts down at 20-40%, or straight away if the battery swells and lifts the keyboard or bottom cover. Run powercfg /batteryreport in Windows to see both numbers.

We do not publish a fixed battery price for the Apple MacBook Air 15" (M4, 2025); send the model and the part number on the old battery on WhatsApp for a quote. Every battery and fitting job carries our 30-day warranty. Pay cash at the shop, by bank transfer, JazzCash or Easypaisa.