The complete bipartite graph Km,nK_{m,n}Km,n is planar if and only if:
m=nm = nm=n
m+n≤6m + n \leq 6m+n≤6
m⋅n≤10m \cdot n \leq 10m⋅n≤10
min(m,n)≤2\min(m,n) \leq 2min(m,n)≤2