# High-Cardinality Tags Inflating Datadog Custom Metrics Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/high-cardinality-tags-inflating-datadog-custom-metrics Under Datadog's cardinality-based pricing, a custom metric is a unique combination of a metric name and tag values, including the host tag. By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version Under Datadog's cardinality-based pricing, a custom metric is a unique combination of a metric name and tag values, including the host tag. PointFive Research Cloud cost research at PointFive Datadog service [Datadog Custom Metrics](https://www.pointfive.co/efficiency-hub/cloud-services/datadog-custom-metrics) Category [Other](https://www.pointfive.co/efficiency-hub/service-category/other) Reference CER-0540 Type Excessive Ingestion or Processing ## Explanation Why the waste happens and who it affects. Every new tag value creates a new billable timeseries, so a metric tagged with an unbounded identifier such as user ID, request ID, session ID, container ID or pod name can turn one metric name into thousands of custom metrics. HISTOGRAM and DISTRIBUTION metrics multiply this again: each generates five custom metrics per tag combination by default, and enabling percentiles on a distribution adds five more. The count is driven by application code, not infrastructure size. A developer adds a tag for debugging, or a library emits per-pod tags, and the monthly average of distinct timeseries jumps above the per-host allotment, often for timeseries no dashboard or monitor queries. The cost lands on the central observability budget while the cause sits in individual services, so attribution needs Datadog's per-metric and per-tag usage tools. ## Billing model The pricing dimensions that drive this cost. This applies to the cardinality-based Custom Metrics model; contracts on Metric Name pricing SKUs are billed differently. Custom metric A unique combination of metric name and tag values, including host; billable usage is the monthly average of distinct custom metrics per hour Account allotment 100 indexed custom metrics per host on Pro and 200 on Enterprise, pooled across the account Indexed custom metrics overage Each 100 indexed custom metrics above the allotment billed at the rate in your contract Ingested custom metrics For metrics configured with Metrics without Limits, each 100 ingested custom metrics above the allotment billed at $0.10 Distribution multiplier 5 custom metrics per tag combination for count, sum, min, max and avg, plus 5 more when percentiles are enabled ## How to detect 5 checks to find it in your estate. - On the Plan and Usage Custom Metrics tab, review billable usage, the usage trend and the Top Custom Metrics table, then open the top metric names in Metrics Summary - In the metric details side panel, use the Custom Metrics Tags Cardinality Explorer to find the tag keys driving the count, such as unbounded user, request, session, container or pod identifiers - Use Metrics Volume Management to find the largest metric names and those spiking in volume, and chart datadog.estimated\_usage.metrics.custom.by\_metric and datadog.estimated\_usage.metrics.custom.by\_tag for attribution by service or team - In Metrics Summary, filter with the Query Activity and Related Assets facets to find custom metrics that are not queried and not used on any dashboard, notebook, monitor or SLO - Review distribution metrics with percentile aggregations enabled and HISTOGRAM metrics with extra histogram\_aggregates or histogram\_percentiles in datadog.yaml ## How to fix 5 ways to remove the waste. - Remove unbounded tags at the source, or aggregate them before submission, and keep identifiers such as request or user IDs in traces and logs instead of metric tags - Use Metrics without Limits to set an allowlist of queryable tags on high-cardinality metrics, starting from the recommended configuration based on actively queried tags, and give unqueried metrics an empty tag configuration - Disable percentile aggregations on distributions that do not need them, and trim histogram\_aggregates and histogram\_percentiles in the Agent configuration - Restrict who can change tag configurations with the metrics\_tags\_write permission, and review changes in the audit trail - Tradeoff: metrics configured with Metrics without Limits are also billed for ingested custom metrics above the allotment, so check the tag configuration cardinality estimator before saving and do not save a configuration whose indexed count is higher than ingested ## Documentation Vendor references for pricing and configuration. - [Custom Metrics Billing docs.datadoghq.com](https://docs.datadoghq.com/account_management/billing/custom_metrics/) - [Best Practices for Custom Metrics Governance docs.datadoghq.com](https://docs.datadoghq.com/metrics/guide/custom_metrics_governance/) - [Metrics without Limits docs.datadoghq.com](https://docs.datadoghq.com/metrics/metrics-without-limits/) - [Estimated Usage Metrics docs.datadoghq.com](https://docs.datadoghq.com/account_management/billing/usage_metrics/) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - Datadog Log Management CER-0539 ### [Indexing All Ingested Datadog Logs Without Exclusion Filters](https://www.pointfive.co/efficiency-hub/inefficiencies/indexing-all-ingested-datadog-logs-without-exclusion-filters) Datadog Log Management charges separately for ingesting logs and for indexing them. At list prices, indexing a million 1 KB events for 15 days ($1.70) costs many times more than ingesting that gigabyte ($0.10). By default a log index has... Other - Datadog APM CER-0542 ### [Datadog APM Span Ingestion and Indexing Beyond Host Allotments](https://www.pointfive.co/efficiency-hub/inefficiencies/datadog-apm-span-ingestion-and-indexing-beyond-host-allotments) Datadog APM bills per APM host, and each host brings a monthly allotment of ingested span volume and indexed spans. Usage above the pooled allotment is billed separately per GB ingested and per million spans indexed. Overage usually comes... Other - Datadog Infrastructure Monitoring CER-0544 ### [Datadog Container Usage Exceeding Per-Host Allotment](https://www.pointfive.co/efficiency-hub/inefficiencies/datadog-container-usage-exceeding-per-host-allotment) Each Datadog Infrastructure host license on the Pro or Enterprise plan includes a small number of monitored containers, 5 or 10 per host depending on the plan, pooled across the whole account. Dense Kubernetes nodes, sidecar-heavy pods,... Other --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.