Taken from Ploi:

1. Turn off all running swap processes: swapoff -a
2. Resize swap fallocate -l 1G /swapfile (change 1G to the gigabyte size you want it to be)
3. CHMOD swap: chmod 600 /swapfile
4. Make file usable as swap mkswap /swapfile
5. Active the swap file swapon /swapfile

To verify your swap size run the following command and you will see the swap size: free -m