Kubernetes IP Calculator
Live tool: https://jhooq.com/tools/kubernetes-ip-calculator/
How many IP addresses does your EKS, GKE, AKS or on-premises Kubernetes cluster really need? Pick the cloud, the instance type or the pods per node, the node count and the zones. You get:
- the maximum pods per node and which rule set it (ENI formula, prefix delegation, managed node group cap),
- the VPC addresses every node takes, including the warm pool the CNI keeps,
- the subnet size per zone (EKS), the node Pod range and Pod secondary range (GKE), the node subnet and pod space (AKS), the nodes a pod CIDR holds plus the node VLAN and MetalLB pool (on-premises: kubeadm, Mirantis MKE, RKE2, OpenShift, Tanzu, Talos),
- a diagram of the cluster (VPC, zones, subnets, one tile per node with a square per address) drawn from the same numbers,
- a checks list with a link to the documentation page each rule came from,
- one click to open the result in the VPC Subnet Planner, and Terraform, CLI and Markdown exports.
Single HTML file, no build step for users, nothing leaves the browser. The share link stores the inputs in the URL fragment.
The rules it applies
| Cloud and mode | Max pods per node | What a node takes from your network | Source |
|---|
| EKS, VPC CNI secondary IPs | ENIs x (IPs per ENI - 1) + 2; managed node groups cap at 110 (< 30 vCPU) or 250 | every attached ENI is fully allocated; WARM_ENI_TARGET 1 keeps a spare ENI | EKS instance types, VPC CNI README |
| EKS, prefix delegation | slots x 16 + 2, capped at 110 or 250 | prefixes x 16 + one primary per ENI; needs contiguous /28 blocks | EKS prefix mode |
| EKS, custom networking | (ENIs - 1) x (IPs per ENI - 1) + 2 (m5.large: 20), or x 16 with prefixes (290); same cap | 1 address per node in the node subnet; Pod ENIs and their addresses in a per-zone subnet from a secondary CIDR (100.64.0.0/10); 5 IPv4 CIDR blocks per VPC by default | EKS custom networking, tutorial, VPC quotas |
| EKS, Windows nodes | IPs per ENI - 1 on the single ENI (m5.large: 9), or x 16 with Windows prefix delegation (144); kubelet max-pods default 110 | primary + one per Pod + warm-ip-target 1 (minimum-ip-target 3), or primary + prefixes x 16 | Windows support, prefix mode for Windows |
| EKS, IPv6 cluster | (ENIs x (IPs per ENI - 1) x 16) + 2, same cap; prefix delegation mandatory | one IPv4 per node; Pods and Services IPv6 only; /80 per node from the subnet /64; Nitro only; no custom networking; set at creation | IPv6 clusters, IPv6 best practices |
| EKS, cluster subnets | - | 6 free addresses per subnet minimum (16 recommended), 2 AZs; service CIDR /12 to /24 in a private range, no VPC overlap | EKS network requirements, API reference |
| GKE, VPC-native | 8 to 256 (default 110, Autopilot 32) | node Pod range /(31 - ceil(log2(pods))); node pool Pod range >= /24; primary range reserves 4 | GKE max Pods per node, VPC-native clusters |
| AKS, Azure CNI Overlay | 250 | one VNet address per node; pods from a /24 per node out of the pod CIDR (default 10.244.0.0/16) | AKS IP planning |
| AKS, Azure CNI Pod Subnet | 110 | nodes in the node subnet, pods in a VNet pod subnet in batches of 16; pod subnet <= /16 | AKS dynamic IP allocation |
| AKS, Azure CNI node subnet (legacy) | 30 | (nodes + surge) + (nodes + surge) x maxPods, assigned up front | AKS IP planning |
This is the beginning of the README. Read the rest at the original. Read the full README ↗
