Time Series Cardinality Calculator

Why cardinality matters

In Prometheus and VictoriaMetrics, each unique combination of label values is a separate time series. Each time series requires index entries, memory, and disk space.

• The product below is an upper bound, not a measurement: labels are rarely independent.
• Capacity depends on active-series churn, scrape interval, retention, replication, queries, and hardware.
• Validate with prometheus_tsdb_head_series and a load test; never approve a design from one universal threshold.
• Unbounded identifiers such as request IDs usually belong in an event or trace store, even when today’s count appears small.

Rule: never use user IDs, session IDs, or request IDs as TSDB labels. These belong in event tables (ClickHouse), not metric labels (Prometheus).