Kubernetes Resource (CPU/Memory) Calculator
Right-Size Kubernetes Pod CPU and Memory Requests with Confidence
Avoid over-provisioning and resource starvation by calculating optimal CPU and memory requests/limits for your Kubernetes workloads. This tool serves DevOps, SREs, and developers aiming for efficient cluster utilization and stable application performance.
Kubernetes Resource Calculator
Right-size your pod's CPU & memory to improve stability and optimize costs.
About This Tool
The Kubernetes Resource (CPU/Memory) Calculator is a vital utility for any engineer working with containerized applications. Setting resource `requests` and `limits` is one of the most critical and challenging aspects of managing workloads on Kubernetes. If you set requests too low, your pods might be scheduled on nodes without enough resources. If you set limits too high, you create resource waste, driving up cloud costs. If you set them too low, your application might be CPU-throttled or terminated with an 'OOMKilled' error. This tool provides a heuristic-based approach to finding a sane starting point. By describing your workload's characteristics—its language, workload type, and expected load—it recommends a balanced set of CPU and memory values. This helps teams avoid common performance pitfalls, improve cluster stability, and optimize cloud spend by packing pods more efficiently onto nodes.
How to Use This Tool
- Select the workload type that best describes your application (e.g., Web Server, Batch Worker).
- Choose the primary programming language or framework your application uses.
- Input your application's baseline memory usage (at idle) and how much additional memory is consumed per user or request.
- Enter the peak number of concurrent users or requests you expect the pod to handle.
- Click "Calculate Resources" to see the recommended `requests` and `limits` for CPU and memory.
- Copy the generated YAML snippet and use it as a starting point in your Kubernetes deployment manifest.
In-Depth Guide
Understanding Requests vs. Limits
In Kubernetes, `requests` and `limits` are the two most important resource management settings. **Requests** are what Kubernetes guarantees your pod. The scheduler will only place a pod on a node that has at least the requested amount of CPU and memory available. This ensures your pod has the resources it needs to start and run. **Limits** are the maximum amount of resources your pod is allowed to use. If your application tries to use more memory than its limit, it will be terminated (OOMKilled). If it tries to use more CPU, it will be throttled. Setting both is crucial for stability.
Quality of Service (QoS) Classes
The way you set requests and limits determines your pod's QoS class. **Guaranteed:** This is when `requests` and `limits` are set to the same value for both CPU and memory. These pods are the highest priority and are the last to be killed if a node runs out of resources. **Burstable:** This is when `requests` are set lower than `limits`. The pod can "burst" up to its limit if resources are available. This is the most common class. **BestEffort:** This is when no requests or limits are set. These pods have the lowest priority and are the first to be killed. You should never use BestEffort for production workloads.
Measuring CPU in Kubernetes
CPU is a "compressible" resource. If your app needs more CPU, it gets throttled and runs slower. CPU is measured in "milliCPU" or "millicores". `1000m` is equal to 1 full vCPU core. A typical request might be `100m` (one-tenth of a core), with a limit of `1000m` (1 full core). This means the pod is guaranteed 10% of a core and can burst up to using a full core if needed.
Measuring Memory in Kubernetes
Memory is an "incompressible" resource. If your app needs more memory than is available, it cannot be throttled; it must be killed. Memory is measured in bytes, but typically specified using units like `Mi` (Mebibytes) or `Gi` (Gibibytes). A typical request/limit pair might be `requests: { memory: "256Mi" }` and `limits: { memory: "1024Mi" }`. This means the pod is guaranteed 256 Mebibytes and can use up to 1024 Mebibytes before it is OOMKilled.