How 95th percentile billing works
95th percentile billing samples the network port every 5 minutes, records inbound and outbound throughput, sorts the samples for the month, and discards the top 5%. The 95th-percentile sample of the remaining values becomes your billable rate. In a 30-day month with samples every 5 minutes, that's 8,640 samples — discarding 432 (the top 5%) and billing on the next-highest peak.
The model has been the dominant wholesale internet pricing scheme since the late 1990s, and it survives because it lets carriers price for sustained throughput rather than instantaneous peaks. A workload that bursts to 1 Gbps for 10 minutes per day but averages 50 Mbps will be billed roughly at the 50 Mbps rate, not the 1 Gbps peak. The math: 10 minutes at 1 Gbps over a 30-day month is 10/(30*24*60) = 0.023% of samples — well within the 5% discard window. Conversely, a workload that sustains 500 Mbps for two hours every day spends 4.16% of the month above 500 Mbps. Just barely under the 5% threshold, so the 95th percentile lands at 500 Mbps and you're billed for it. The 5% rule is generous to bursty traffic and harsh to sustained traffic — match your workload accordingly.
Burstable vs unmetered: what the marketing actually means
'Burstable' typically means: port speed N Gbps, billing on 95th percentile (or a similar metric). 'Unmetered' typically means: port speed N Gbps, no usage cap stated — but almost always with a fair-use clause that lets the provider throttle or terminate accounts that sustain near line-rate. True unmetered with no cap and no fair-use clause is rare and almost always priced at a premium.
Burstable plans price the port speed (the headline bandwidth number) and the actual usage separately. You get a 1 Gbps NIC and pay for whatever 95th-percentile rate you use, often with a base allocation included (e.g., 'first 100 Mbps included, overage at 0.50 EUR/Mbps'). Unmetered plans bundle the port speed and usage into a single price, simplifying the bill but shifting the risk: the provider is now exposed if you sustain near line-rate, and they protect themselves with fair-use language. Read it carefully — a typical fair-use clause says something like 'sustained utilization above X% of port capacity for Y consecutive hours may result in throttling or contract review,' where X is often 50% and Y is often 24-72 hours. If your workload sustains higher than that, unmetered is functionally metered and you should price as if it were.
When unmetered is actually metered
Three tells reveal a fake-unmetered plan: a fair-use clause in the terms of service, an undisclosed throttle threshold (e.g., 'up to 1 Gbps' that quietly tops out at 200 Mbps under load), and a clause permitting the provider to convert the contract to metered billing if you 'abuse' the bandwidth. Always read sections marked 'Acceptable Use' or 'Fair Usage' before signing.
Genuine unmetered exists — high-tier dedicated server plans where the provider has bought enough commit transit to support every customer running line-rate simultaneously. But on most lower-tier and entry VPS plans, 'unmetered' is a marketing term that papers over a soft cap. Common patterns to watch for: (1) a stated port speed without a stated 95th-percentile or transfer cap and only a vague 'fair use' clause; (2) marketing copy that says 'unlimited bandwidth' but a control panel that surfaces a TB/month meter; (3) a clause buried in the AUP that lets the provider 'limit bandwidth to ensure network stability for all customers.' If you can't find a hard, written number — either a TB/month allowance, a 95th-percentile billable rate, or a guaranteed minimum throughput at line-rate — you are on a soft-capped plan no matter what the marketing says.
How to read any bandwidth claim
Ignore port speed. Look for three specific numbers: (1) the monthly transfer cap in TB or PB, (2) the 95th-percentile billable rate in Mbps if applicable, and (3) the overage price in EUR/USD per Mbps or per GB. Any provider unwilling or unable to give all three is selling you ambiguity, not bandwidth.
Port speed is the easiest number to advertise and the least useful in isolation. A '10 Gbps unmetered' plan sounds impressive but means nothing without context: is the port shared (one 10 Gbps NIC across 50 customers)? Is sustained throughput at line-rate actually permitted? What happens at month-end? Move the conversation to the three numbers above. If the provider quotes 'unmetered, 1 Gbps port,' translate it: 1 Gbps line-rate for 30 days = 1 * 86,400 * 30 / 8 = 324 TB. If their fair-use clause caps you at 50% sustained, that's 162 TB. If their actual published cap is 32 TB/month, that is what unmetered actually means. Compare like for like.
Bandwidth calculator: TB/month for common tiers
At 100% port utilization for 30 days: 100 Mbps = ~32 TB, 1 Gbps = ~324 TB, 10 Gbps = ~3,240 TB, 25 Gbps = ~8,100 TB. Real workloads rarely sustain 100%, but these are the absolute ceilings for any 'unmetered at port speed N' claim. Halve them if the fair-use clause caps you at 50%; quarter them at 25%.
| Port speed | 100% sustained (30d) | 50% sustained | 25% sustained | 10% sustained |
|---|---|---|---|---|
| 100 Mbps | ~32 TB | ~16 TB | ~8 TB | ~3 TB |
| 1 Gbps | ~324 TB | ~162 TB | ~81 TB | ~32 TB |
| 2.5 Gbps | ~810 TB | ~405 TB | ~202 TB | ~81 TB |
| 10 Gbps | ~3,240 TB | ~1,620 TB | ~810 TB | ~324 TB |
| 25 Gbps | ~8,100 TB | ~4,050 TB | ~2,025 TB | ~810 TB |
| 100 Gbps | ~32,400 TB | ~16,200 TB | ~8,100 TB | ~3,240 TB |
Picking the right model for your workload
For predictable traffic, 95th percentile is usually cheapest. For bursty traffic with low average and tall peaks, also 95th percentile (the top 5% gets discarded). For sustained high traffic with no idle periods, metered TB-per-month is most transparent. Unmetered is best for moderate-volume customers who hate variable bills more than they want the absolute lowest price.
Three quick decision rules. If your average-to-peak ratio is below 1:5 (workload is bursty), 95th percentile reliably beats every other model because the discard window covers your peaks. If your average-to-peak ratio is above 1:1.5 (workload is sustained), metered TB pricing is most accurate and prevents surprises. If your monthly TB usage is well below the unmetered fair-use line and you want zero billing variance, unmetered is fine — the cap simply never bites. The wrong choice in each case can double or triple your annual bandwidth cost: bursty traffic on a metered plan pays for peaks it didn't really use, sustained traffic on an unmetered plan triggers fair-use clauses and gets throttled.