95th-percentile billing prices bandwidth not on total bytes but on sustained peak throughput: the provider samples your usage (e.g. every 5 minutes), discards the highest 5% of samples, and bills on the remaining peak. The idea is to charge for the capacity you routinely consume while forgiving brief spikes.
It changes optimization priorities compared to per-GB egress: smoothing peaks becomes valuable, so a few very high but short bursts (a live premiere) may be "free" under the discarded 5%, while a consistently high baseline is expensive. Understanding which billing model a CDN or transit link uses is essential to modeling delivery cost accurately.
