Exported file size much larger than estimated

[EMPexchange]

Hi all, I'm using premiere pro (new to this, so I know this is probably something I'm doing!) to do some very minor editing and adding of captions into a video (recorded zoom) before we load it into our online community. We have a file size limit of 1gb/file for the online community. When I go to the export panel, it estimates the file will be ~8080 mb and then becomes 1.2gb when actually exported. I cannot figure out what's going on. I've read a few similar posts and have tried to do some of the recommendations. 

[Kevin-Monahan]

Hi EMPexchange,

You might try one of the H.264 presets for adaptive bit rate. Hopefully, you can lower the data rate for the final output. It is odd that the estimate was off by so much, though. I'll see if I can find the other cases where this has happened. 

Thanks,
Kevin

[Mike Dziennik]

0.19 Mbps is a very tiny data-rate for HD video - it's less than you're using for the audio!

I think your multiplexer is set wrong.

Start with the H.264 Match source low bitrate preset and then tweak the target bitrate. You should get under 1GB with a target over 2Mbps.