Ubuntu Swap Size

Below table shows the amount swap space required depending on your RAM size. 

        RAM(MB) No hibernation  With Hibernation        Absolute maximum
         256     256              512                     512
         512     512             1024                    1024
        1024    1024             2048                    2048

        RAM(GB) No hibernation  With Hibernation        Absolute maximum
          1      1                2                       2
          2      1                3                       4
          3      2                5                       6
          4      2                6                       8
          5      2                7                      10
          6      2                8                      12
          8      3               11                      16
         12      3               15                      24
         16      4               20                      32
         24      5               29                      48
         32      6               38                      64
         64      8               72                     128
        128     11              139                     256

https://help.ubuntu.com/community/SwapFaq 

Find out if I have a swap partition size