Size NetFlow collector storage and export bandwidth from flow rate, sampling and retention.
Flow export volume is the flow rate times the record size; sampling divides the rate directly, which is why 1-in-1000 sampling is the standard way to make high-rate interfaces affordable to monitor. Retention and compression scale the stored figure. Flow data grows faster than any other telemetry — a busy edge router at 20,000 flows per second produces around 95 GB a day unsampled, which decides whether you need sampling or a bigger array.
NetFlow Storage
storage = flows/s ÷ sampling × 86400 × record bytes × retention ÷ compression, with NetFlow v9 records running 40–70 bytes each.
Exporter to collector bandwidth
export bandwidth = exported flows/s × record bytes × 8
storage = flows/s ÷ sampling × 86400 × record bytes × retention ÷ compression, with NetFlow v9 records running 40–70 bytes each. Flow export volume is the flow rate times the record size; sampling divides the rate directly, which is why 1-in-1000 sampling is the standard way to make high-rate interfaces affordable to monitor. Retention and compression scale the stored figure.
Flow data grows faster than any other telemetry — a busy edge router at 20,000 flows per second produces around 95 GB a day unsampled, which decides whether you need sampling or a bigger array.
This calculator takes 5 inputs: Flows per second, Bytes per flow record, Sampling rate (1 in N), Retention period, Compression ratio. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.