Enter time-sampled bandwidth measurements (for example, 5‑minute average rates over a billing period) into the calculator to determine the 95th percentile bandwidth.
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95th Percentile Bandwidth Formula
The following equation describes the common “95th percentile billing” method used in networking.
B_{95}=x_{(n-\lceil 0.05n\rceil)}- Where B95 is the 95th percentile bandwidth value
- x(k) is the k-th smallest value in the sorted list of sampled bandwidth measurements
- n is the total number of samples in the billing/measurement period
To calculate the 95th-percentile bandwidth (billing convention), sort the sampled bandwidth measurements, discard the highest 5% of samples, and then take the highest remaining sample.
What is a 95th Percentile Bandwidth?
Definition:
95th percentile bandwidth is a usage-based metric derived from many bandwidth measurements taken over time (often at fixed intervals like 5 minutes). It is the bandwidth level that 95% of those measured intervals are at or below.
In 95th percentile billing, this is typically implemented by discarding the highest 5% of measured samples (short spikes) and billing based on the next-highest value.
How to Calculate 95th Percentile Bandwidth?
Example Problem:
The following example outlines the steps and information needed to calculate 95th Percentile Bandwidth.
First, collect bandwidth usage samples over time. For example, suppose you have 20 samples (in Mbps):
10, 12, 15, 20, 25, 30, 32, 35, 40, 45, 50, 52, 55, 60, 65, 70, 75, 80, 90, 120
Next, sort the samples (they are already sorted here), discard the highest 5% of samples. With 20 samples, 5% is 1 sample, so discard the single highest sample (120 Mbps).
The highest remaining sample is 90 Mbps, so the 95th percentile bandwidth is:
B95 = 90 Mbps
FAQ
What is the significance of calculating the 95th percentile bandwidth?
The 95th percentile bandwidth calculation is significant because it allows ISPs and network managers to fairly bill and manage network usage. By calculating the 95th percentile, they can ignore the top 5% of usage spikes, which might not represent typical usage, ensuring users are billed for their regular usage pattern rather than occasional peaks.
How does the 95th percentile bandwidth differ from average bandwidth usage?
The 95th percentile bandwidth measurement differs from average bandwidth usage in that it disregards the top 5% of data points that could be outliers or rare spikes in usage. This method provides a more consistent and fair assessment of bandwidth usage over time, whereas average bandwidth usage could be significantly affected by short periods of high traffic.
Can the 95th percentile bandwidth calculation be applied to any network service?
Yes, the 95th percentile bandwidth calculation can be applied to various network services, including internet service providers, data center networks, and corporate networks. It's a versatile metric that helps in managing network resources efficiently across different types of network infrastructures and service models.
