How to convert flac to MP3 free software?

Being a big vinyl fan, I own a lot of old records on them. I like listening to them on the record but I cannot play it through my cellphone. So I ripped them using my turn table to the computer into lossless format.flac. I transferred the files to my phone but the phone says invalid format which means it can't support that format. So, I will just have to convert these files to mp3 so that my phone can play them. I want to know what are the free softwares around which are good to convert flac to mp3. Please suggest a few and links from where I can download them. How to use them would be an added help?