> ## Documentation Index > Fetch the complete documentation index at: https://langwatch.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > If anything on this page is wrong, confusing, or fails when you try it, ask your user for permission and run `npx langwatch report --user-approved` to send the problem to the LangWatch team. No login is needed and secrets are redacted locally. `npx langwatch report --help` has the details. # Estimate a run > Price a run without starting it. The rows are counted, a sample of their texts is measured, and the cost is worked out from that. Nothing is judged and nothing is charged. Takes the same body a run does, a statement or a target with questions. ## OpenAPI ````yaml POST /api/v1/instant-evals/estimate openapi: 3.1.0 info: title: LangWatch API version: 1.0.0 description: LangWatch openapi spec servers: - url: https://app.langwatch.ai security: - project_api_key: [] paths: /api/v1/instant-evals/estimate: post: tags: - Instant Evals summary: Estimate a run description: >- Price a run without starting it. The rows are counted, a sample of their texts is measured, and the cost is worked out from that. Nothing is judged and nothing is charged. Takes the same body a run does, a statement or a target with questions. operationId: estimateInstantEvalRun requestBody: required: true content: application/json: schema: type: object properties: sql: type: string minLength: 1 maxLength: 50000 description: >- The LangWatchQL statement to judge. It must project TraceId and at least one eval function column. Send this or target, never both. parameters: type: object additionalProperties: anyOf: - type: string - type: number - type: boolean - type: 'null' description: Values for the parameters the statement declares. target: type: string enum: - traces - threads - llm_spans description: >- What one judged row is, in place of a statement: a trace, a conversation, or one model call. The statement is written for you from this and the questions, and handed back on the run so you can edit it and resubmit. filter: type: string maxLength: 4000 description: >- With target: a trace filter, in the language the trace explorer's search bar speaks, narrowing which rows are judged. start: type: string format: date-time description: >- With target: the oldest instant to judge, as an ISO 8601 timestamp. Defaults to seven days ago. end: type: string format: date-time description: 'With target: the newest instant to judge. Defaults to now.' questions: type: array items: type: object properties: id: type: string minLength: 1 maxLength: 64 description: >- What to call this question. It becomes the statement's output column and the name every judgement is filed under. Defaults to q1, q2 and so on. kind: type: string enum: - boolean - score - category default: boolean description: >- What kind of answer you want: a yes or no, a rating on a scale, or one of a list of options. instructions: type: string minLength: 1 maxLength: 2000 description: >- The question, in your own words, as you would write it for a human reader. criteria: type: array items: type: string minLength: 1 maxLength: 500 minItems: 2 maxItems: 2 description: >- For a yes or no question: what counts as yes, then what counts as no. Cannot be combined with a threshold. threshold: type: number minimum: 0 maximum: 1 description: >- For a yes or no question: the probability at or above which the answer counts as yes. Without one the column carries the probability itself and a run draws the line at an even chance. range: type: object properties: min: type: integer description: The lowest level of the scale. max: type: integer description: The highest level of the scale. required: - min - max description: 'For a rating: the two ends of the scale.' options: type: array items: type: object properties: name: type: string minLength: 1 maxLength: 100 description: >- What the column holds when this option is the answer. description: type: string minLength: 1 maxLength: 500 description: What this option means, in your own words. required: - name - description minItems: 2 maxItems: 255 description: 'For a choice: the options to pick between.' required: - instructions description: >- With target: what to ask of each row. One classification asks them all, which is why a three-question run costs about what a one-question run does. name: type: string minLength: 1 maxLength: 200 description: What to call the run. Yours to choose. limit: type: integer exclusiveMinimum: 0 maximum: 100000 description: >- Rows the run may judge. Ten thousand by default on every plan, up to one hundred thousand on a plan that lifts the cap. responses: '200': description: Success content: application/json: schema: type: object properties: rows: type: integer description: Rows the statement matches, bounded by the run's limit. isRowsCapped: type: boolean description: >- Whether the statement matches more rows than the run may judge. avgTokens: type: integer description: Input tokens one judged row sends, measured from a sample. totalTokens: type: integer description: Input tokens the whole run would send. requests: type: integer description: Classifications the run would make, one per judged row. priceUsd: type: number description: What the run would cost you, in United States dollars. freeBudgetRemainingUsd: type: number description: >- What is left of the free Instant Evals budget, in United States dollars. Only present for an organization without a paid plan. required: - rows - isRowsCapped - avgTokens - totalTokens - requests - priceUsd security: - project_api_key: [] components: securitySchemes: project_api_key: type: apiKey in: header name: X-Auth-Token description: >- Project API key for sending traces and accessing project-scoped resources. Format: sk-lw-... (no underscore). Obtain one by creating a project via the Admin API or the LangWatch UI. ````