Kubernetes resource calculator

Convert CPU and memory quantities, see how many pods fit on a node, and total the requests in your manifests.

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Convert a quantity

Quantity

How many pods fit on a node

CPU request per pod

Memory request per pod

Replicas

Node allocatable CPU

Node allocatable memory

Max pods per node

DaemonSet CPU per node

DaemonSet memory per node

DaemonSet pods per node

Total requests from manifests

Manifests (YAML)

Units that catch people out

Mi and Gi are powers of 1024; M and G are powers of 1000, so 1G is only 0.93Gi. A lower-case m means milli: memory: 128m is 0.128 bytes, not 128 megabytes. CPU 1 is one vCPU, and 100m is a tenth of one.

Where to find allocatable

Allocatable is node capacity minus what the kubelet and OS reserve. On AKS that is noticeably less than the VM size. Read it from the cluster, and sum what DaemonSets already request:

kubectl get nodes -o custom-columns=NAME:.metadata.name,CPU:.status.allocatable.cpu,MEM:.status.allocatable.memory,PODS:.status.allocatable.pods
kubectl describe node <node> | sed -n '/Allocated resources/,/Events/p'

A pod’s request is the sum of its containers, or its largest init container if that is bigger. Sidecars (init containers with restartPolicy: Always) count toward the sum. If only a limit is set, the request defaults to the limit.