Estimate RabbitMQ queue memory, disk use and consumer requirements.
Default queues hold messages in memory, so a growing backlog threatens the broker itself. Lazy queues move messages to disk immediately, which keeps memory flat at the cost of higher latency. A RabbitMQ broker hitting its memory watermark blocks publishers entirely, so backlog growth is an availability risk rather than just a latency one.
RabbitMQ Queue
Backlog = (publish rate − consume rate) × period; memory depends on the queue mode
Backlog = (publish rate − consume rate) × period; memory depends on the queue mode Default queues hold messages in memory, so a growing backlog threatens the broker itself. Lazy queues move messages to disk immediately, which keeps memory flat at the cost of higher latency.
A RabbitMQ broker hitting its memory watermark blocks publishers entirely, so backlog growth is an availability risk rather than just a latency one.
This calculator takes 5 inputs: Publish rate, Consume rate, Average message size, Period to project, Queue mode. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.