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Kafka Capacity Planner

Size your Kafka cluster across throughput, storage, partitions, and fault tolerance. Choose a preset or enter your own workload parameters.

How to Use This Calculator

1. Enter Your Workload

Start with a preset that matches your use case, or select Custom and enter your own values. The key input is your peak message rate — this is what the cluster must handle during traffic spikes, not your average load.

2. Customize Hardware (Optional)

Expand Broker Hardware Spec to match your actual server configuration. Disk count, disk size, and NIC speed directly affect how many brokers you need. Defaults represent a typical production setup.

3. Read the Results

The calculator sizes your cluster across four dimensions: throughput, storage, partitions, and fault tolerance. The final broker count is the maximum across all four — and the bottleneck is highlighted.

4. Watch the Utilization Bars

Green (<60%) means comfortable headroom. Orange (60–80%) is tight — plan for growth. Red (>80%) means you need more brokers or bigger hardware.

Pro tip: Always size for peak, not average. Kafka clusters that run fine at normal load can fall over during spikes if they weren't sized for it. Add 30% storage headroom (already included in this calculator) and keep per-broker NIC utilization under 70%.
Workload Parameters
Normal load
Peak load (used for sizing)
Sample from actual messages or estimate from schema
Business or regulatory requirement
Count all consuming applications
e.g. Spark Streaming executors × cores
Cluster Recommendation
Brokers
7
Storage bottleneck
Total Storage
754.8 TB
7-day retention
Network Throughput
3.5 GB/s
41.9% NIC utilization
Total Partitions
~128
OK — 0.5% of limit
Storage is the limiting factor. 7-day retention with RF=3 requires 754.8 TB total. To reduce broker count: shorten retention, enable tiered storage, or use larger disks.
Per-Broker Utilization
Storage74.9%
Network41.9%
Partitions0.5%
Per-Broker Spec
128 GB RAM · 24 vCores · 12×12 TB NVMe SSD · 10 GbE NIC
Per broker: 107.8 TB storage · 502.9 MB/s network · ~18 partitions