80% is the sweet spot.

Yes, if you want to maximize battery lifespan, keep your MacBook Air charged to around 80% most of the time. Lithium-ion batteries degrade fastest when sitting at full charge or fully drained.

Apple knows this. That’s why macOS has Optimized Battery Charging — it learns your routine and holds at 80% until you’re about to unplug. But if you’re like me and keep your laptop plugged in all day, that feature might not kick in often enough. In that case, a third-party tool like AlDente or Battery Health 2 lets you set a hard limit. Set it to 80% and forget it.

You don’t need to obsess. Just don’t leave it at 100% for weeks on end unless you enjoy replacing batteries sooner than necessary. Future you will thank present you.