The 95th percentile is a widely used mathematical calculation to evaluate the
regular and sustained utilization of a network connection. It is commonly used
among all major internet transit and peering networks, as well as datacenters
and ISPs for both capacity planning and/or calculating usage. It roughly means
‘for most of the time this was the throughput on the line’.
The 95th percentile is a good number to use for billing as it can allow the
customer throughput bursts without additional financial compensation. Basically
the 95th percentile says that 95% of the time, the usage is below this amount.
Conversely, 5% of the time, usage is above that amount.
There are important factors to percentile calculation:
Sampling interval, or how often samples are taken (called also "data
A percentile is calculated on some set of data points.
Every data point
represents the average bandwidth used through the sampling interval, calculated
as the number of bytes (or KB/MB/GB etc.) transferred divided by the sampling
interval length in seconds (effectively representing the average utilization for
single sampling interval). The number is expressed in a data transfer rate as
bits per second (Kbps/Mbps/Gbps).