Billing Dimensions in Confluent Cloud

Confluent Cloud bills you on these dimensions: cluster capacity (CKU or eCKU), data ingress and egress, storage, Cluster Linking, connectors, ksqlDB, Flink SQL, Tableflow, the Real-Time Context Engine, Unified Stream Manager, Kafka Streams, audit logs, Stream Governance, and the Advanced Security add-on. For support plan billing, see Confluent support plans.

This section explains how Confluent Cloud calculates each dimension. Dollar amounts shown here are examples, not necessarily current prices. For current list prices, see the Confluent Cloud pricing page.

Important

Confluent storage and throughput is calculated in binary gigabytes (GB), where 1 GB is 2³⁰ bytes. This unit of measurement is also known as a gibibyte (GiB).

The following table lists the Costs API line item and unit of measure for each Confluent Cloud billing dimension. For more information, see the Costs API.

Dimension	Line item	Unit of measure
CKU/eCKU	KAFKA_NUM_CKUS	Cost per CKU/eCKU per hour
Kafka ingress	KAFKA_NETWORK_WRITE	Cost per GB written
Kafka ingress through Kafka REST APIs	KAFKA_REST_PRODUCE	Cost per GB written
Kafka egress	KAFKA_NETWORK_READ	Cost per GB read
Kafka storage	KAFKA_STORAGE	Cost per GB stored per hour
Cluster Linking links	CLUSTER_LINKING_PER_LINK	Cost per link per hour
Cluster Linking ingress	CLUSTER_LINKING_WRITE	Cost per GB written
Cluster Linking egress	CLUSTER_LINKING_READ	Cost per GB read
Connector capacity for Dedicated Kafka cluster	CONNECT_CAPACITY	Cost per hour
Connect task	CONNECT_NUM_TASKS	Cost per task per hour
Connect data transfer	CONNECT_THROUGHPUT	Cost per GB written or read
Custom Connect task	CUSTOM_CONNECT_NUM_TASKS	Cost per task per hour
Custom Connect data transfer	CUSTOM_CONNECT_THROUGHPUT	Cost per GB written or read
ksqlDB Confluent Streaming Unit (CSU)	KSQL_NUM_CSUS	Cost per CSU per hour
Confluent Unit for Flink (CFU)	FLINK_NUM_CFUS	Cost per CFU per minute
Tableflow topic hours	TABLEFLOW_NUM_TOPICS	Cost per topic per hour
Tableflow data processed	TABLEFLOW_DATA_PROCESSED	Cost per GB processed
Tableflow index data processed	TABLEFLOW_INDEX_DATA_PROCESSED	Cost per upsert index GB processed
Tableflow storage (Confluent managed storage only)	TABLEFLOW_STORAGE	Cost per GB stored per hour
Unified Stream Manager connected node	USM_CONNECTED_NODE	Cost per connected node per hour
Kafka Streams	KAFKA_STREAMS	Cost per eCKU per hour, or per CKU on Dedicated clusters, for each cluster with a connected Kafka Streams application
Audit logs	AUDIT_LOG_READ	Cost per GB of data read from audit log topics
Stream Governance base	GOVERNANCE_BASE	Cost per hour
Schema Registry schema	SCHEMA_REGISTRY	Cost per schema per hour
Stream Governance rule	NUM_RULES	Cost per rule per hour
Confluent support plan	SUPPORT	Cost per hour, prorated from the monthly price
Advanced Security add-on	SECURITY_ADD_ON	Percentage of eligible pre-support usage charges
Credit	PROMO_CREDIT	Credit issued by Confluent

Monitor your usage

To track usage against a billing dimension before it appears on your bill, query the relevant metric in the Metrics API. Confluent Cloud also sends built-in notifications for specific events, such as free-trial consumption and service quota thresholds; see Notifications for Confluent Cloud to view available notification types and configure them in the Confluent Cloud Console or through the API.

Regional multiplier

A regional multiplier is a price factor based on region and cloud provider, applied to the base rate of a billing dimension that uses one.

For example, Apache Kafka® ingress in AWS us-east-1 might have a 1x regional multiplier, while the same dimension in Google Cloud asia-east2 might have a 1.2x regional multiplier, meaning the affected rate in that region is 1.2 times the base rate. These specific values are examples only. The multiplier itself doesn’t vary by dimension, but whether a given dimension uses it, and its base rate, does.

The following resources use regional multipliers:

• Kafka ingress and egress

• Cluster Linking

• Confluent Cloud for Apache Flink CFU pricing

• Real-Time Context Engine

Compare billing units for Kafka clusters

Confluent Cloud bills Kafka cluster capacity using one of two units, depending on cluster type: a Confluent Unit for Kafka (CKU) or an Elastic Confluent Unit for Kafka (eCKU). Both quantify pre-allocated resources and they differ in how you are billed.

Attribute	CKU	eCKU
Cluster type	Dedicated	Basic, Standard, Enterprise, and Freight
Billing basis	Fixed: pay for CKUs set at cluster creation	Elastic: pay for capacity used per hour
What you pay when idle	Full CKU cost, because capacity stays reserved	Minimum if any consumption; nothing at zero consumption
Maximum capacity	Number of CKUs configured	Fixed ceiling set at cluster creation: costs can’t exceed it

CKU

A CKU is a fixed unit of pre-allocated capacity for Dedicated Kafka clusters in Confluent Cloud. Each CKU bundles throughput, partition, and connection limits. You set the number of CKUs at cluster creation and pay per CKU per hour.

CKU charges accrue each hour based on the configured capacity of your cluster. You can expand and shrink Dedicated clusters. When you expand or shrink a Dedicated cluster, you are billed for the new CKU value in the next hour following the change in capacity.

To stop your Kafka clusters from accruing billed usage, delete your clusters in the Confluent Cloud Console, or use the Confluent CLI.

eCKU

An eCKU is a unit of capacity for Basic, Standard, Enterprise, and Freight Kafka clusters in Confluent Cloud. Unlike CKUs, eCKUs scale elastically. You pay only for the capacity you use in a given hour, up to a fixed ceiling. Cost is per eCKU per hour.

Basic, Standard, Enterprise, and Freight clusters are elastic and automatically scale up to a fixed ceiling. The ceiling governs how much maximum capacity your Kafka cluster can use. However, you are only billed for the capacity that you use in a given hour, up to the maximum allowed by the ceiling. The billing system monitors the actual consumption of each dimension. For each hour, you are billed for the maximum number of eCKUs used. For example, if dimensional usage oscillates between 2 and 3 eCKUs in a single hour, you are billed for 3 eCKUs.

Basic, Standard, Enterprise, and Freight clusters have a minimum capacity. If the capacity you use is less than the minimum, you pay the minimum. If your cluster is at zero consumption across all dimensions, you pay nothing. Zero consumption across all dimensions means your cluster has no partitions and no topics (or all topics have been deleted). It also means there is no other capacity usage from an eCKU billable dimension, including ingress, egress, client connections, connection attempts, or requests. For more information, see eCKU/CKU comparison and Cluster provisioning and scaling.

Pricing changes for Basic and Standard clusters

As of April 16, 2024, Basic and Standard clusters use eCKUs instead of Base and Partitions. This applies only to Confluent Cloud organizations created on or after that date; earlier organizations keep their existing pricing model and limits. See the legacy billing model for details, or contact the Confluent Cloud Support Portal with questions.

Ingress and egress

Confluent Cloud charges you for all data transfers, including produce and consume requests and every other incoming or outgoing request. This includes charges for requests made by Cloud Console to display messages in message browser. An extra ingress charge applies for using the Produce (v3) REST API, before the regional multiplier is applied. All ingress and egress charges are then multiplied by a regional multiplier based on the cloud provider region.

Storage

Confluent Cloud charges for storage based on the total post-replication volume of data on a Kafka cluster. Because Confluent Cloud replicates data three times for high availability, billed storage is typically about three times the volume you write. To reduce storage usage, you can configure the retention.bytes and retention.ms properties on a topic. To learn more, see Topic Settings and Edit topics.

Partitions

Confluent Cloud doesn’t charge for partitions on any type of Kafka cluster, but the number of partitions you use can have an impact on eCKU. To determine eCKU limits for partitions, Confluent Cloud counts only leader partitions, the pre-replication count, across a cluster. For more information, see eCKU/CKU comparison.

Only partitions that are visible in the Cloud Console count toward this limit. Partitions internal to Kafka itself, such as consumer offsets, are not visible in the Cloud Console and don’t count.

This distinction applies differently to Connect, depending on how you run it:

• A self-managed Connect worker creates its config, offset, and status topics directly on your Kafka cluster. These topics are visible in the Cloud Console, so their partitions count toward your partition limit and eCKU. They’re also compacted, so they count toward the Enterprise compacted partition sub-limit as well.

• A fully managed connector’s internal state is managed in Confluent’s own infrastructure. It isn’t created as a topic on your cluster and isn’t visible in the Cloud Console, so it doesn’t count toward your partition limit or eCKU. Only the connector’s data topics count.

Basic and Standard clusters in Confluent Cloud organizations created before April 16, 2024 use per-partition billing instead. For more information, see legacy partition billing.