Calculate optimal Kubernetes node sizes based on your workload requirements. Estimate allocatable resources after kubelet reservations, plan node counts, and optimize cluster efficiency for cost-effective infrastructure.
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Planning a Kubernetes deployment? Our K8s Node Calculator helps you determine optimal node sizes and counts based on your workload requirements. Factor in kubelet reservations, DaemonSet overhead, and eviction thresholds to maximize resource utilization and minimize infrastructure costs.
Kubernetes node sizing is the process of selecting appropriate compute resources (CPU and memory) for your cluster nodes based on workload demands. Unlike traditional VMs, Kubernetes reserves a portion of each node's resources for system operations—the kubelet, container runtime, and OS processes. The remaining 'allocatable' resources are what's actually available for your pods. Proper node sizing balances cost efficiency (larger nodes have lower overhead percentage) with fault tolerance (more smaller nodes spread risk).
Allocatable Resources Formula
Allocatable = Total - Kubelet Reserved - Eviction Threshold - DaemonSet OverheadOversized nodes waste money on unused capacity, while undersized nodes lead to poor bin-packing efficiency. Optimal sizing can reduce infrastructure costs by 20-40%. Larger nodes have proportionally less reserved resources, improving allocatable-to-total ratio.
Kubernetes reserves CPU and memory using a sliding scale formula. A 4 vCPU node reserves ~7% CPU, but a 16 vCPU node reserves only ~4%. Understanding these formulas helps you maximize the resources available for your actual workloads.
Spreading pods across multiple nodes provides resilience. If one node fails, only a fraction of your workload is affected. The calculator helps balance efficiency against blast radius by showing how many nodes you need for your pod count.
Pods fail to schedule when nodes lack sufficient allocatable resources. By accounting for DaemonSet overhead (kube-proxy, CNI, logging agents) and eviction thresholds, you can ensure your pods will actually fit on the nodes you provision.
When deploying a new Kubernetes cluster, use the calculator to determine initial node sizes. Start with your workload requirements and let the calculator recommend the most efficient configuration.
Compare your current node sizes against calculator recommendations. Many teams discover they're running inefficient node sizes—either too small (high overhead) or too large (poor utilization).
Planning for growth? Input your projected pod counts to see how your infrastructure needs to scale. The calculator helps you decide whether to add more nodes or upgrade to larger sizes.
When migrating from VMs to Kubernetes, use the calculator to translate your VM resource allocations into appropriate pod requests and node sizes. Account for the container overhead model.
Kubernetes uses a tiered formula. For CPU: 6% of first core + 1% of next core + 0.5% of next 2 cores + 0.25% of remaining cores. For memory: 25% of first 4GB + 20% of next 4GB + 10% of next 8GB + 6% of next 112GB + 2% above 128GB. This means larger nodes have proportionally less overhead.