> ## Documentation Index
> Fetch the complete documentation index at: https://docs.costgraph.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# How Does Costgraph Work?

This guide walks through the algorithm Costgraph utilises in providing recommendations.

## Costgraph Algorithm

Costgraph is a tool that provides recommendations for the requests and limits of containers in a Kubernetes cluster. The recommendations are based on the historical utilisation of the resources in the cluster. The algorithm used by Costgraph is as follows:

<Tabs>
  <Tab title="Recommendation Algorithm">
    Costgraph works by:

    1. Fetching a maximum of 45 days metric data from Prometheus on resource utilisation with a 5-minute granularity.
    2. Aggregating the fetch information by container and node, each metric is partitioned by namespace.
    3. Filtering is done on the data retrieved to remove outliers and optimise the stable trend of the captured window.
    4. We use the filtered data to generate recommendations for the requests and limits.
    5. The generated recommendations are computed per container and node per each namespace the application runs.
    6. Each recommendation is deployed to parquet and the resulting files are ingested into Postgres.
  </Tab>

  <Tab title="QoS Algorithm">
    In obtaining the requests and limits, Costgraph uses the algorithm:

    1. The *Current* value is always the requests from kubernetes if specified. If not, then there is no QoS, and we use our computed value.
    2. When defining the *Recommendation*, we compute two values, the scaled computed value which is the `100 * computed_value / expected_utilisation_percent` and the minimum request over the maximum 45 day period we sampled utilisation metrics
    3. The *Recommendation* is the `max(scaled computed value, minimum request)`
    4. The *Savings* is the difference between the *Current* and the *Recommendation*
  </Tab>

  <Tab title="Resource Quota Algorithm">
    In any cluster, the recommended resource quota at any time is double the limits in use at the point of recommendation.

    ```bash theme={null}
    recommended_resource_quota_namespace = 2 * total_limit_in_use_namespace
    ```

    We use the recommended limit values to compute the recommended resource quota values.
  </Tab>
</Tabs>

## Cost Usage Reporting (CUR) Pricing

All pricing information on Costgraph is provided through our [pricing API](/api-reference/introduction). Costgraph currently all major cloud providers, with [our list](/api-reference/introduction#supported-cloud-providers) expanding fast.

Once the CPU and Memory values are computed, the values are multiplied by the per-hour CPU and Memory pricing to obtain the pricing results.