Messaging costs explained: requests, deliveries, retries, and payload size
Messaging bills look small until they scale. The reliable model is: volume (messages/month) x deliveries (including retries) x payload size. This hub links the key pricing checklists and estimation helpers.
1) Define your unit (publish vs delivery)
- Publish volume: messages you send into the system.
- Delivery volume: messages delivered to consumers (can be > publishes due to fan-out and retries).
- Always write down what your provider bills: request, delivery, or processed GB.
2) Model retries and replays explicitly
- Use a deliveries-per-message assumption (1.0, 1.2, 2.0, etc.).
- During incidents, retries can jump by 10x. Model a peak scenario.
- Redrives/replays and batch consumers can change request counts.
3) Payload size is the hidden multiplier
- Large messages can dominate transfer and downstream logging.
- Split payload sizes by message type (events vs large blobs).
- Tool: Transfer from requests and payload size
Related tools
More messaging guides
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A practical workflow to estimate SNS delivery volume: start from publishes, model matched fan-out (after filter policies), add a retry multiplier for failures, and validate with metrics so budgets survive incidents.
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A practical workflow to estimate billable SQS request volume: start from messages/month, model requests per successful message (Send/Receive/Delete), and add the multipliers (retries, empty receives, poison loops) that cause spikes.
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A high-leverage playbook to reduce SNS costs: reduce fan-out (deliveries), reduce delivery retries by fixing endpoints, and prevent alert storms with dedupe and rate limits — with a validation plan.
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A practical SNS pricing checklist: publish requests, delivery requests by protocol mix, fan-out after filter policies, and the retry/alert-storm patterns that create surprise delivery volume.
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Compare SQS vs SNS cost with a practical checklist: request types, retries, fan-out, payload transfer, and the usage patterns that decide the bill.
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Related calculators
Data Egress Cost Calculator
Estimate monthly egress spend from GB transferred and $/GB pricing.
API Response Size Transfer Calculator
Estimate monthly transfer from request volume and average response size.
VPC Data Transfer Cost Calculator
Estimate data transfer spend from GB/month and $/GB assumptions.
Cross-region Transfer Cost Calculator
Estimate monthly cross-region transfer cost from GB transferred and $/GB pricing.
RPS to Monthly Requests Calculator
Estimate monthly request volume from RPS, hours/day, and utilization.
API Request Cost Calculator
Estimate request-based charges from monthly requests and $ per million.
FAQ
What drives messaging cost most often?
Request/delivery volume and retries. Fan-out patterns multiply deliveries, and large payloads amplify both transfer and downstream log/storage cost.
How do I estimate quickly?
Estimate messages published per month, average deliveries per message (including retries), and average payload size. Then check if your provider prices per request, per delivery, or per GB processed.
What breaks estimates?
Ignoring retries and redrives, underestimating fan-out, and treating payload size as constant when you have a heavy tail (a few large messages).
Last updated: 2026-01-22