95th percentile billing is a way of charging for bandwidth based on measured use rather than a fixed rate. The provider samples your traffic at regular intervals through the billing period, discards the top 5% of samples, and bills you on the highest sample that remains. It is common for IP transit, data center and colocation internet, and burstable dedicated internet access, where customers want room to burst without paying for peak capacity all month.
At a glance
- Usage is sampled at regular intervals, commonly every five minutes, across the billing period.
- The highest 5% of samples are discarded, so the bill reflects the next-highest sample rather than the absolute peak.
- You usually pay a commit level as a monthly minimum, plus an overage price per Mbps above it.
- How inbound and outbound traffic are combined, and the sampling interval, vary by provider.
- It is a billing method, not a speed limit; the port size and burst rate set how fast you can go.
What problem it solves
Bandwidth needs are rarely flat. Backups run at night, software updates go out in bursts, and a product launch or event can multiply traffic for a few hours. Paying a flat price for enough capacity to cover the peak means paying for headroom you use only occasionally. Paying strictly for total data transferred makes the bill hard to predict.
95th percentile billing sits between the two. You get a port larger than your typical use, so traffic can burst when it needs to, and the provider bills on the highest sample left after discarding the top 5%, which reduces the effect of isolated peaks but doesn’t guarantee a rate below your absolute peak. For the provider, the method roughly tracks the capacity it has to keep available for you.
How it works
Sampling. The provider’s equipment records how much traffic passes through your port, typically as an average rate over each sampling interval. Five-minute intervals are common, but not universal.
Ranking and discarding. At the end of the billing period, the samples are sorted from highest to lowest and the top 5% are dropped. This is a share of the samples, not a time allowance: whether a given burst falls within the discarded samples depends on the rest of the month’s traffic and on the contract’s sampling, direction and aggregation rules.
Billing. The highest remaining sample is your 95th percentile rate. Most contracts pair it with a commit level, the minimum you pay for each month. The commit is a billing floor, distinct from a committed information rate, which is a performance commitment on the link. If your 95th percentile is at or below the commit, you pay the commit. If it is above, you pay overage on the difference, usually at a per-Mbps price that may be higher than the committed price.
Direction. Providers handle inbound and outbound traffic differently. Many calculate the percentile for each direction and bill the higher; some add both directions; some bill only one. A site that mainly serves content will look very different from one that mainly downloads.
Port size. The physical port, for example 1 Gbps or 10 Gbps on a bandwidth commit of a few hundred Mbps, caps how high a burst can go. The port and the commit are priced separately in some contracts and bundled in others.
For comparing transit providers and commit structures, see our IP transit solution page.
When it matters for buyers
- Choosing between flat-rate and burstable service. Model a few months of real traffic against both before deciding.
- Planning large transfers. A sustained backup, migration or launch can set your billable rate for the month, so model it against your usage data first.
- Reviewing a surprise overage. Ask for the sample data and check it against your own monitoring.
- Renewing transit or colocation internet. Commit level, overage price and the direction rule are all negotiable.
- Multi-provider setups. Traffic engineering between providers changes each one’s 95th percentile, so keep it in mind when shifting traffic.
Questions to ask vendors
- What sampling interval do you use, and where is it measured?
- How do you treat inbound and outbound traffic: higher of the two, the sum, or one direction?
- What is our commit, what is the overage price per Mbps, and does it change at higher volumes?
- Can we see the raw samples behind each bill, and how long are they kept?
- How are samples handled when the measuring system misses an interval or the port is down?
- Are multiple ports or sites aggregated into one percentile, or billed separately?
- Can we change the commit level during the term, up or down?
How it differs from burst rate
The burst rate is a speed ceiling: how far above your committed rate the provider will let traffic go, often limited by the port size. 95th percentile billing is a measurement and pricing method: how the provider turns the traffic you actually sent, including any bursts, into a monthly charge. A service can allow generous bursting and still bill on the 95th percentile, so a long burst can be allowed technically and still set the billable rate on the invoice.