1TB = 1 trillion bytes actual formatted capacity less. Battery life varies by use and configuration.
The Apple TV app movie playback test measures battery life by playing back HD 1080p content with display brightness set to 8 clicks from bottom. Testing conducted by Apple in October 2020 using preproduction MacBook Air systems with Apple M1 chip and 8-core GPU, configured with 8GB of RAM and 512GB SSD.1TB = 1 trillion bytes actual formatted capacity less.