internal storage – How much space would it take to record a 1 hour video?

I have like literally 1 GB of space on my tablet, and I want to record a 1 hour video in 1080p HD quality. Now, I know that these kind of things vary from app to app, but on average, how much space does it take? I also have an SD card with 27 GB of space on it. Is there a way to make the video go straight to the SD card while recording, without needing it to go onto internal storage first? Because I really don’t want to delete any more apps. Please help me.