kubernetes
Kubernetes Node Sizing Calculator
Calculate the right number and size of Kubernetes worker nodes for your workloads. Supports Hetzner Cloud and Vultr with verified pricing.
Related tool
K8s Cluster Cost
Calculate the monthly cost of running a self-managed Kubernetes cluster on Hetzner Cloud, Vultr, or DigitalOcean. Choose server types for control planes, workers, and load balancers with HA mode.
Kubernetes Node Sizing Principles
Right-sizing Kubernetes nodes balances cost, reliability, and operational simplicity. Undersizing causes OOM kills and CPU throttling; oversizing wastes money.
Resource Requests vs Limits
Kubernetes uses requests for scheduling (bin packing) and limits for enforcement:
- ›Request: guaranteed minimum — the scheduler uses this to find a node with enough space
- ›Limit: maximum allowed — exceeding CPU limit throttles, exceeding memory limit OOM-kills
Always set both. A pod with no requests can land on an already-saturated node.
Overcommit Strategy
| Resource | Safe Overcommit | Risk |
|---|---|---|
| CPU | 2–3× | Throttling (recoverable) |
| RAM | 1–1.2× | OOM kill (disruptive) |
System Pod Overhead
Every node runs non-negotiable system pods:
- ›
kube-proxy— iptables/ipvs rules - ›
coredns— DNS resolution (2 replicas cluster-wide) - ›
metrics-server— HPA requires this - ›CNI plugin (Flannel/Calico/Cilium) — pod networking
Combined overhead: ~200–500 MB RAM, ~0.1–0.3 vCPU per node.
Cluster Autoscaler
For production, pair static nodes with the Kubernetes Cluster Autoscaler. Set a minimum node count to handle baseline traffic, and let the autoscaler add nodes under load. This is more cost-effective than over-provisioning.
Key Terms
Full glossary →kubeadm
A tool for bootstrapping Kubernetes clusters. It automates the setup of control plane components and joining worker nodes, following Kubernetes best practices.
etcd
A distributed key-value store used by Kubernetes to store all cluster state and configuration. etcd is the single source of truth for the entire cluster.
cert-manager
A Kubernetes controller for automating TLS certificate management. cert-manager can issue certificates from Let's Encrypt, Vault, or internal CAs, and automatically renews them.
Helm
A package manager for Kubernetes. Helm charts bundle Kubernetes manifests into reusable packages with configurable values, versioned and published to chart repositories.
Frequently Asked Questions
How do I find the right CPU and memory requests for my services?
Run `kubectl top pods --all-namespaces` to see actual CPU/memory usage. Use this as a baseline for requests (set requests = average usage, limits = peak usage). Don't guess — incorrect requests lead to either waste or OOM kills.
Is it better to have fewer large nodes or more small nodes?
Fewer large nodes: simpler to manage, less Kubernetes overhead, but larger blast radius on node failure. More small nodes: better fault tolerance, finer-grained bin packing. A common production pattern is 3–5 medium nodes (cx43/cx53), scaling out via the Cluster Autoscaler.
Why does the calculator add 15% system overhead?
Kubernetes system pods (kube-proxy, CoreDNS, metrics-server, CNI plugin) consume roughly 10–20% of node resources. This overhead is non-negotiable — it's always there. The 15% default is a conservative estimate for a typical cluster.
What is a safe CPU overcommit ratio for production?
2× is the standard production default. CPU is compressible — if pods request more than available, they get throttled, not killed. 3× is fine for development clusters or batch workloads. Never overcommit memory beyond 1.2× in production — OOM kills are disruptive.
Related Tools
K8s Cluster Cost
Calculate the monthly cost of running a self-managed Kubernetes cluster on Hetzner Cloud, Vultr, or DigitalOcean. Choose server types for control planes, workers, and load balancers with HA mode.
Longhorn Storage
Calculate the total storage required for Longhorn distributed block storage, including replica overhead, snapshot retention, and S3 backup sizing on Hetzner Object Storage.
HPA Thresholds
Calculate the right HPA (Horizontal Pod Autoscaler) CPU and memory thresholds for your Kubernetes workloads. Get absolute target values in millicores and MiB.
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