First charge of ipad air = 14 hrs, 50 minutes battery life. That was running browsers, youtube, and six hours of garageband creation. Brightness was on 30%. No doubt the biggest factor in extending battery. Still plenty bright for me. This is much higher than the advertised 12 hours. Followup charges are usually two hours per 10% drain, at least on the top end. Ex: from 100% to 90% = 2 hours. It goes down from there, otherwise I would be getting 20 hours battery life. This was the best surprise about ipad air. Makes a huge difference.