MongoDB Cloud Manager Backup: calculating how much you will be charged

getTotalSizeofDatabases.js

var dbNames = [];
var sum = 0;
var dblist = db.getMongo().getDBs();
for (var key in dblist) {
    if(key === "databases") {
        for (var i = 0; i < dblist.databases.length; i++){
            if (dblist.databases[i].name !== "local") {
                dbNames.push(dblist.databases[i].name);
            }
        }
    }
} 
function formatSizeUnits(bytes){
  if      (bytes>=1000000000) {bytes=(bytes/1000000000).toFixed(2)+' GB';}
  else if (bytes>=1000000)    {bytes=(bytes/1000000).toFixed(2)+' MB';}
  else if (bytes>=1000)       {bytes=(bytes/1000).toFixed(2)+' KB';}
  else if (bytes>1)           {bytes=bytes+' bytes';}
  else                        {bytes='0 byte';}
  return bytes;
}
for (var i = 0; i < dbNames.length; i++) {
  var indexSize = db.getMongo().getDB(dbNames[i]).stats().indexSize;
  var dataSize =  db.getMongo().getDB(dbNames[i]).stats().dataSize;
  var total = indexSize + dataSize;
  sum += total;
  print("db name: " + dbNames[i] + " | indexSize: " + formatSizeUnits(indexSize) + " | dataSize: " + formatSizeUnits(dataSize) + " | total: " + formatSizeUnits(total));
}
print("total size of all dbs: " + formatSizeUnits(sum));

For every primary in the deployment (including every primary for every shard in a sharded cluster), sum the total dataSize and indexSize. Here’s a little script that does this.