Pricing

Cloud Pub/Sub pricing is based on:

  • Message ingestion and delivery
  • Seek-related message storage: snapshots and retained acknowledged messages

Message ingestion and delivery

Message delivery pricing

Message ingestion and delivery are priced per volume of data transmitted in a calendar month. The first 10 gigabytes of usage are free. After that, the price for ingestion or delivery of messages is $40 per TiB.

The data volume of a message is the sum of the following:

  • Message body (the length of the string).
  • For each attribute, the size of the key and its value.
  • 20 bytes per timestamp.
  • The size of the message_id string.
  • Additional optional fields, such as those associated with early access and other restricted access APIs.

A minimum of 1000 bytes per publish, push or pull request is assessed regardless of message size. This means that when you send small messages, it may be cheaper to batch multiple messages per request. Since the data volume is based on message properties, ingestion and delivery charges apply only to publish requests and data delivered using pull, streamingPull or push operations. Other operations do not generate throughput charges.

If you pay in a currency other than USD, the prices listed in your currency on Google Cloud Platform SKUS apply. The rate listed is per TiB (240 bytes, or approximately 1.01 trillion bytes).

Data region egress fees

The fees for internet egress and message delivery between GCP regions are consistent with the Compute Engine network rates, with the following exceptions:

  • There are no zone egress fees for Cloud Pub/Sub usage.
  • Egress to Google products is not exempt from egress fees.

For example, a 1 MiB message published in us-west1 and delivered to a subscriber in europe-west1 results in charges totaling 3 MiB between two distinct SKUs:

  • 2 MiB of Message Delivery Basic (1 MiB of publish and the delivery)
  • 1 MiB of Inter-Region Data Delivery from the Americas to EMEA

To understand your usage, you can export your billing data to BigQuery. Once you set this up, you can use a query like this one to understand your usage:

SELECT TIMESTAMP_TRUNC(usage_start_time, day) as usage_date,
  sku.description,
  usage.unit,
  sum(usage.amount) as egress_volume
FROM `BILLING_EXPORT_TABLE`
WHERE
  _PARTITIONTIME >= TIMESTAMP("2019-01-01")
  AND service.description = "Cloud Pub/Sub"
  AND (sku.description like "Internet data%"
      OR sku.description like "Inter-region data%")
GROUP BY usage_date, sku.description, usage.unit;

Example: message ingestion and delivery

To illustrate the overall costs of operation you might expect, consider an application that publishes 1024-KB messages to a topic with two subscriptions, at a rate of 1 MiB/second. Assuming that the subscribers are keeping up, Cloud Pub/Sub is ingesting 1 MiB/second and delivering 2 MiB/second, for a total data transmission rate of 3 MiB/second. Over the course of a 30-day month, this example amounts to 3 MiB/second x 3600 seconds/hour x 24 hours/day x 30 days/month x 1 month/(2^20 MiB/TiB) = 7.416 TiB. After subtracting the free tier (10 GB), the data volume is 7.406 TiB in the $60 per TiB tier and the charge is $296.24.

Minimum billable volume

The minimum billable volume of data per request (not message) is 1 KB of data. For example, 100 publish requests, each containing one 500-byte message, have an actual data volume of 50 KB but a billable data volume of 1 KB/request x 100 requests = 100 KB. However, if all 100 messages are published in a single Publish request, the billable data volume is equal to the actual one (50 KB).

Cross-project billing

If you are using Cloud Pub/Sub across projects, Cloud Pub/Sub fees are billed to the project that contains the requested resource (such as a subscription). For example, a service account in project A might be given subscriber access to a subscription in Project B (that is under billing account B). Billing account B is billed for the data that is pulled from the subscription by service account A. Alternatively, if the subscription resides in project A (even if it is attached to a topic in project B), account A is billed for data that is pulled from the subscription.

Seek-related message storage

Pricing

Message storage fees, at a rate of $0.27 per GiB-month, are charged in these cases:

  • A subscription is configured to retain acknowledged messages to make it possible to re-process them using seek. In this case, storage fees are charged for retained acknowledged messages.
  • A snapshot of a subscription is created. In this case, message storage fees are charged for storing the snapshot’s unacknowledged messages.

Example: subscription with retained acknowledged messages

Consider the message ingestion example, except with a single subscription that is configured to retain acknowledged messages:

  • The subscription’s topic has a steady 1MiB/second rate of incoming data.
  • The subscriber is keeping up with the data on the subscription, consuming it at 1 MiB/second and has negligible new message backlog.
  • The subscription is configured to retain acknowledged messages for 7 days.
  • The acknowledged message volume grows by 1MiB/second x 3600 seconds/hour x 24 hours/day = 86.4 GiB/day.
  • After 7 days, retained acknowledged messages start expiring and the total volume of stored acknowledged messages plateaus at 7 days x 86.4 GiB/day = 605GiB.
The total monthly fee for storing this volume of messages is approximately 605 GiB-month x $0.27/GiB-month = $163.

Example: snapshot message storage fees

Snapshot message storage fees consist of an incremental charge for new messages published to the snapshot’s topic and a one-time fee at the time of creation. Consider a snapshot of the subscription with retained acknowledged messages. The snapshot has a lifetime of seven days unless it is deleted earlier, since the subscription from which it is created has no backlog of unacknowledged messages. The data published in the first minute (60 MiB) is stored for 7 days - 1 minute, the data published in the second minute for 7 days - 2 minutes, and so forth. This scenario results in a backlog size of 605 GiB when the snapshot expires, amounting to 1/2 x 605 GiB x 7 days = 2118 GiB-days of storage used, for which the charge is 2118 GiB-days x (1/30 months/day) x $0.27/GiB-month = $19 in a 30-day month. Thus, snapshots are a potentially cost-effective alternative to acknowledged message retention.

Example: snapshot of a subscription with a backlog

If the subscription has a backlog of unacknowledged messages when the snapshot is created, a one-time fee equivalent to storing that backlog for the full seven days is charged. For example, consider a subscription with a 10-GiB unacknowledged message backlog. The one-time fee at the time of snapshot creation would be 10 GiB x 7 days / 30 days/month x 0.27/GiB-month = $0.63.

Resource location restriction implications

A message storage policy can result in additional region egress (network) fees if the policy forces the data to exit a GCP region. Consider a message that is:

  • Published in region A
  • Routed to region B for storage
  • Delivered to a subscriber client in region C

In this case:

  • The project that contains the topic is billed for network egress from region A to region B.
  • The project that contains the subscription is billed for egress from region B to region C.

The project that contains the topic will be charged an egress fee only if the published message is stored in a region different from the region where the message was published (that is, B is actually a different region from A). The project that contains the subscription will be charged an egress fee only if the published message is stored in a region different from where the subscriber client is (C is not the same as B).

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Cloud Pub/Sub Documentation