That is actually on the small side for mine. I tend to render at a high bitrate though, usually 50Mb/40Mb but I only do that cause YouTube re-encodes it anyway so i give it as much data as possible to work with. I use Sony Movie Studio Platinum 13 with a modified AVC profile (the youtube 1080p). But for longer videos I reduce it to 30Mb/20Mb, high profile, 60 fps, progressive download.
I found they usually come out around, my last video is about 7 mins and weighed in at 1.7GB, 1080p60. Used super high settings for it though. The best thing to do is select a short section to render and test different bitrates. Depending on the content you can sometimes get away with 20Mb/15Mb with the High profile.