Kubernetes Capacity Calculator
Calculate Kubernetes cluster node requirements for your workload
How to use Kubernetes Capacity Calculator
- 1Enter the CPU and memory requests of a single pod and how many replicas you run.
- 2Enter node size (CPU/memory) and the system reservation overhead.
- 3Read how many nodes are needed and the cluster utilization before deploying.
Estimating Kubernetes cluster capacity
nodes = ceil(totalReq / (nodeCap × (1 - sysReserve))); util = totalReq / (nodes × nodeCap)Kubernetes schedules on requests, not limits, so you must size for the sum of requests plus a buffer for system pods and bin-packing inefficiency.
Reserving 10–20% of each node for kube-system and eviction thresholds prevents the scheduler from marking nodes unschedulable under load.
Frequently asked questions
Requests or limits drive scheduling?
Scheduling uses requests; limits only cap usage and can cause OOM if set too low.
Why reserve node capacity?
kube-system pods and eviction thresholds need headroom or nodes become unschedulable.
How do I improve bin-packing?
Right-size requests, use topology spread and avoid tiny nodes that waste reservation overhead.
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