Track costs ↗

wandb guide intermediate cost-management ide

Summary: Track and manage costs for LLM operations in Weave

Original Documentation

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

Track and manage costs for LLM operations in Weave

Adding a custom cost#

You can add a custom cost by using the add_cost method. The three required fields are llm_id, prompt_token_cost, and completion_token_cost. llm_id is the name of the LLM (e.g. gpt-4o). prompt_token_cost and completion_token_cost are cost per token for the LLM (if the LLM prices were specified inper million tokens, make sure to convert the value). You can also set effective_date to a datetime, to make the cost effective at a specific date, this defaults to the current date.

    import weave
    from datetime import datetime

    client = weave.init("my_custom_cost_model")

    client.add_cost(
        llm_id="your_model_name",
        prompt_token_cost=0.01,
        completion_token_cost=0.02
    )

    client.add_cost(
        llm_id="your_model_name",
        prompt_token_cost=10,
        completion_token_cost=20,
        # If for example I want to raise the price of the model after a certain date
        effective_date=datetime(2025, 4, 22),
    )
    ```
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  <span class="tab-start" data-tab-title="TypeScript"></span>
```plaintext
    This feature is not available in TypeScript yet.  Stay tuned!
    ```
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## Querying for costs

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  <span class="tab-start" data-tab-title="Python"></span>
You can query for costs by using the [`query_costs`](/weave/reference/python-sdk/trace/weave_client#method-query-costs) method.
There are a few ways to query for costs, you can pass in a singular cost id, or a list of LLM model names.

```python
    import weave

    client = weave.init("my_custom_cost_model")

    costs = client.query_costs(llm_ids=["your_model_name"])

    cost = client.query_costs(costs[0].id)
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="TypeScript"></span>
```plaintext
    This feature is not available in TypeScript yet.  Stay tuned!
    ```
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## Purging a custom cost

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  <span class="tab-start" data-tab-title="Python"></span>
You can purge a custom cost by using the [`purge_costs`](/weave/reference/python-sdk/trace/weave_client#method-purge-costs) method. You pass in a list of cost ids, and the costs with those ids are purged.

```python
    import weave

    client = weave.init("my_custom_cost_model")

    costs = client.query_costs(llm_ids=["your_model_name"])
    client.purge_costs([cost.id for cost in costs])
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="TypeScript"></span>
```plaintext
    This feature is not available in TypeScript yet.  Stay tuned!
    ```
  <span class="tab-end"></span>
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## Calculating costs for a Project

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  <span class="tab-start" data-tab-title="Python"></span>
You can calculate costs for a project by using our `calls_query` and adding `include_costs=True` with a little bit of setup.

```python
    import weave

    weave.init("project_costs")
    @weave.op()
    def get_costs_for_project(project_name: str):
        total_cost = 0
        requests = 0

        client = weave.init(project_name)
        # Fetch all the calls in the project
        calls = list(
            client.get_calls(filter={"trace_roots_only": True}, include_costs=True)
        )

        for call in calls:
            # If the call has costs, we add them to the total cost
            if call.summary["weave"] is not None and call.summary["weave"].get("costs", None) is not None:
                for k, cost in call.summary["weave"]["costs"].items():
                    requests += cost["requests"]
                    total_cost += cost["prompt_tokens_total_cost"]
                    total_cost += cost["completion_tokens_total_cost"]

        # We return the total cost, requests, and calls
        return {
            "total_cost": total_cost,
            "requests": requests,
            "calls": len(calls),
        }

    # Since we decorated our function with @weave.op(),
    # our totals are stored in weave for historic cost total calculations
    get_costs_for_project("my_custom_cost_model")
    ```
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  <span class="tab-start" data-tab-title="TypeScript"></span>
```plaintext
    This feature is not available in TypeScript yet.  Stay tuned!
    ```
  <span class="tab-end"></span>
<span class="tab-group-end"></span>

## Setting up a custom model with custom costs

Try our cookbook for [Setting up costs with a custom model](/weave/cookbooks/custom_model_cost).

<span class="card-start" data-card-title="Try in Colab" data-card-href="https://colab.research.google.com/github/wandb/weave/blob/master/docs/./notebooks/custom_model_cost.ipynb"></span>

Link last verified June 7, 2026. View original ↗

Source: Weights & Biases Docs

Link last verified: 2026-03-04