Calculate the percentage of available link capacity currently in use.
Network utilization expresses how much of a link's total capacity is currently being consumed by real traffic, calculated as the actual traffic rate divided by the link's rated capacity, expressed as a percentage. Network engineers commonly treat utilization above 70-80% as a warning threshold, since queuing delay and packet loss increase sharply as a link approaches saturation, well before it reaches 100%.
Utilization percentage
utilization% = (actual_traffic / link_capacity) × 100
Most network engineers treat sustained utilization above 70-80% as a warning sign, since queuing delay, jitter, and packet loss rise disproportionately as a link approaches its ceiling — well before it hits 100% — due to the bursty, non-uniform nature of real traffic.
Both matter for different purposes: average utilization over a day indicates overall capacity headroom for planning, while peak utilization during busy periods reveals whether the link is actually congesting when it matters most to users.
Common approaches include upgrading the link's capacity, applying QoS to prioritize critical traffic, load-balancing across multiple paths (see the ECMP calculator), or identifying and throttling bandwidth-heavy applications that are not business-critical.