You can just do simple maths for rough estimation like
412127124 bytes
=412127.124 KB (divided by 10^3)
=412.127124 MB (divided by 10^6)
=0.412127124 GB (divided by 10^9) and so on
While you should remember that 1024 bytes =1 KB (which i assumed 1000bytes for rough estimate of size)
