Preferably free. I need something that I can convert MP3 files into M4A. It’s less space which is good for my podcasts. Any help would be great. 
Can’t iTunes do that for free? I think it would, since it’s Apple’s format. Sorry if I’m misinformed though.
Hmm wouldn’t know, don’t have iTunes.
I have just have a glance of this page, it seems this one support converting MP3 files into M4A. this is what they describe on their site: OJOsoft M4A Converter not only converts M4A files from audio formats , but also supports converting audio files to M4A. you can find from : Supported Source File Formats to M4A format
I checked. iTunes does convert to m4a (for free obviously). Just drag your mp3 onto the window, right click the file, then choose convert to AAC.