How is Pub/Sub pricing calculated?

Pub/Sub charges per TiB of data published and delivered. The first 10 GiB per month is free. Publishing costs apply once per message, while delivery costs apply per subscription. A message delivered to 5 subscriptions incurs 5x the delivery charge. The minimum billable message size is 1 KB.

What is the minimum message size for billing?

Each publish and delivery operation is billed at a minimum of 1 KB, even if the actual message is smaller. If you publish many small messages (e.g., 100 bytes each), batching them into larger messages can significantly reduce costs by avoiding the 1 KB minimum per publish.

How does Pub/Sub Lite compare in pricing?

Pub/Sub Lite offers zonal messaging at lower cost with per-partition throughput and storage capacity reservations instead of pay-per-message pricing. It requires capacity planning but can be 5-10x cheaper for high-throughput workloads. The trade-off is zonal (not regional) availability and manual scaling.

GCP Pub/Sub Cost Estimator

ServerlessGCP

Estimate Google Cloud Pub/Sub costs based on message volume and delivery.

Pub/Sub Configuration

Messages per Day

Total messages published per day across all topics

Average Message Size (KB)

Minimum billable size is 1 KB per message

Number of Subscriptions

Each subscription receives a copy of every message, multiplying delivery cost

Message Retention (Days)

Retained messages incur storage at $0.27/GB/month

Push Delivery (messages pushed to an endpoint instead of pulled)

Include Free Tier (first 10 GB/month of message delivery)

Raw Output

Output will appear here...

About This Tool

The GCP Pub/Sub Cost Estimator calculates monthly costs based on message volume, message size, and the number of subscriptions. Pub/Sub pricing includes charges for message ingestion, delivery, and snapshot/seek storage. The tool accounts for the free tier, message size minimums (1 KB minimum per publish), and the multiplication effect of multiple subscriptions on delivery costs.

When to Use This Tool

•Estimating monthly Pub/Sub costs for a microservice event bus with known message rates and sizes.
•Calculating how adding more subscriptions to a topic affects delivery costs.
•Modeling the cost impact of message batching to reduce per-message overhead.
•Determining whether message volume stays within Pub/Sub's 10 GB/month free tier.

Frequently Asked Questions

How is Pub/Sub pricing calculated?: Pub/Sub charges per TiB of data published and delivered. The first 10 GiB per month is free. Publishing costs apply once per message, while delivery costs apply per subscription. A message delivered to 5 subscriptions incurs 5x the delivery charge. The minimum billable message size is 1 KB.
What is the minimum message size for billing?: Each publish and delivery operation is billed at a minimum of 1 KB, even if the actual message is smaller. If you publish many small messages (e.g., 100 bytes each), batching them into larger messages can significantly reduce costs by avoiding the 1 KB minimum per publish.
How does Pub/Sub Lite compare in pricing?: Pub/Sub Lite offers zonal messaging at lower cost with per-partition throughput and storage capacity reservations instead of pay-per-message pricing. It requires capacity planning but can be 5-10x cheaper for high-throughput workloads. The trade-off is zonal (not regional) availability and manual scaling.

Related Learning Guides

Pub/Sub & Event-Driven Architecture25 min read
Cost Optimization Guide24 min read

Disclaimer: This tool runs entirely in your browser. No data is sent to our servers. Always verify outputs before using them in production. AWS, Azure, and GCP are trademarks of their respective owners.