Estimate peak bandwidth demand from concurrent users and per-user usage.
Network links must be sized for peak demand, not average demand, or they will congest during busy periods. The peak factor captures how much higher traffic spikes above the average during the busiest moments of the day (e.g. lunch-hour video calls, backup windows). Multiplying the average bandwidth by this factor gives the expected peak; adding a further margin (commonly 20%) accounts for growth and unexpected bursts when sizing the actual circuit to purchase.
Peak bandwidth
peak = average × peak_factor
Network usage is bursty and concentrated around specific events — morning login storms, lunchtime streaming, backup jobs, or synchronized video calls — rather than spread evenly across 24 hours. A peak factor of 2-3x is a common empirical benchmark for typical office and campus networks; consumer residential links can spike even higher relative to their daily average.
Use SNMP or flow-based monitoring (NetFlow, sFlow) over at least a week to record both the average utilization and the 95th-percentile or maximum 5-minute utilization, then divide peak by average to get your network's actual factor.
No — provisioning exactly at the calculated peak leaves no room for growth or unexpected bursts. Most network engineers add 15-30% headroom above the calculated peak, which is why this calculator also shows a recommended link size with a 20% margin.