What is the definition of the density of a graph?
This Wikipedia link on dense graphs might contain what you're looking for.
In particular, for undirected simple graphs, the graph density is defined as $$D = \frac{2|E|}{|V|(|V| - 1)}.$$
While for directed simple graphs, the graph density is defined as $$D = \frac{|E|}{|V|(|V| - 1)},$$ where $|E|$ is the number of edges and $|V|$ is the number of vertices in the graph.
Note that the maximum number of edges is $$\frac{|V|(|V| - 1)}{2}.$$
Yeah! It's right that graph density = no of edges/total no of possible edges.
In directed graph total no of possible edges is |v|*|v-1|,
In undirected graph total no of possible edges is |v|*|v-1|/2.
for e.g. -> let's say there are 3 nodes.All possible edges in undirected graph is 1-2,2-3,1-3 where as in directed graph all edges are 1->2,2->1, 2->3,3->2,1->3,3->1.
For undirected simple graphs, the graph density is defined as D=2|E|/|V|(|V|−1). While for directed simple graphs, the graph density is defined as D=|E|/|V|(|V|−1)