> ## Documentation Index > Fetch the complete documentation index at: https://fal.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Estimate cost > Computes cost estimates using one of two methods: **1. Historical API Price** (`historical_api_price`): - Based on historical pricing per API call from past usage patterns - Takes `call_quantity` (number of API calls) per endpoint - Useful for estimating based on actual historical usage patterns - Example: "How much will 100 calls to flux/dev cost?" **2. Unit Price** (`unit_price`): - Based on unit price × expected billing units from pricing service - Takes `unit_quantity` (number of billing units like images/videos) per endpoint - Useful when you know the expected output quantity - Example: "How much will 50 images from flux/dev cost?" **Authentication:** Required. Users must provide a valid API key. Custom pricing or discounts may be applied based on account status. **Common Use Cases:** - Pre-calculate costs for batch operations - Display cost estimates in user interfaces - Budget planning and cost optimization See [fal.ai pricing](https://fal.ai/pricing) for more details. ## OpenAPI ````yaml /api-reference/platform-apis/openapi/v1.json post /models/pricing/estimate openapi: 3.1.0 info: title: Platform APIs version: v1 description: fal REST API for programmatic access to platform resources. servers: - url: https://api.fal.ai/v1 description: Production server security: [] paths: /models/pricing/estimate: post: tags: - Models - Pricing summary: Estimate cost description: >- Computes cost estimates using one of two methods: **1. Historical API Price** (`historical_api_price`): - Based on historical pricing per API call from past usage patterns - Takes `call_quantity` (number of API calls) per endpoint - Useful for estimating based on actual historical usage patterns - Example: "How much will 100 calls to flux/dev cost?" **2. Unit Price** (`unit_price`): - Based on unit price × expected billing units from pricing service - Takes `unit_quantity` (number of billing units like images/videos) per endpoint - Useful when you know the expected output quantity - Example: "How much will 50 images from flux/dev cost?" **Authentication:** Required. Users must provide a valid API key. Custom pricing or discounts may be applied based on account status. **Common Use Cases:** - Pre-calculate costs for batch operations - Display cost estimates in user interfaces - Budget planning and cost optimization See [fal.ai pricing](https://fal.ai/pricing) for more details. operationId: estimatePricing requestBody: content: application/json: schema: oneOf: - type: object properties: estimate_type: type: string enum: - historical_api_price description: >- Estimate type: historical API pricing based on past usage patterns endpoints: type: object additionalProperties: type: object properties: call_quantity: type: integer minimum: 1 description: >- Number of API calls to estimate (regardless of units per call) required: - call_quantity description: Map of endpoint IDs to call quantities required: - estimate_type - endpoints description: >- Historical API price estimate: Calculates cost based on historical pricing per API call. Useful for estimating costs based on actual usage patterns. - type: object properties: estimate_type: type: string enum: - unit_price description: >- Estimate type: unit price calculation based on billing units endpoints: type: object additionalProperties: type: object properties: unit_quantity: type: number minimum: 0.000001 description: >- Number of billing units expected (e.g., number of images, videos, etc.) required: - unit_quantity description: Map of endpoint IDs to unit quantities required: - estimate_type - endpoints description: >- Unit price estimate: Calculates cost based on unit price × billing units. Useful for estimating costs when you know the expected output quantity. example: estimate_type: historical_api_price endpoints: fal-ai/flux/dev: call_quantity: 100 fal-ai/flux/schnell: call_quantity: 50 examples: historical: value: estimate_type: historical_api_price endpoints: fal-ai/flux/dev: call_quantity: 100 fal-ai/flux/schnell: call_quantity: 50 summary: Historical API price estimate unit_price: value: estimate_type: unit_price endpoints: fal-ai/flux/dev: unit_quantity: 50 fal-ai/flux-pro: unit_quantity: 25 summary: Unit price estimate responses: '200': description: Cost estimates calculated successfully content: application/json: schema: type: object properties: estimate_type: type: string enum: - historical_api_price - unit_price description: The type of estimate that was performed total_cost: type: number minimum: 0 description: Total estimated cost across all endpoints currency: type: string minLength: 3 maxLength: 3 description: Three-letter currency code (ISO 4217, e.g., 'USD') required: - estimate_type - total_cost - currency description: Cost estimation response with total cost example: estimate_type: historical_api_price total_cost: 3.75 currency: USD examples: historical: value: estimate_type: historical_api_price total_cost: 3.75 currency: USD summary: Historical API price estimate result unit_price: value: estimate_type: unit_price total_cost: 1.88 currency: USD summary: Unit price estimate result '400': description: Invalid request parameters content: application/json: schema: type: object properties: error: type: object properties: type: type: string enum: - authorization_error - validation_error - not_found - rate_limited - server_error - not_implemented description: The category of error that occurred message: type: string description: Human-readable error message docs_url: type: string format: uri description: Link to relevant documentation request_id: type: string description: Unique request identifier for debugging required: - type - message description: Error details required: - error description: Standard error response format example: error: type: validation_error message: Invalid request parameters '401': description: Authentication required content: application/json: schema: type: object properties: error: type: object properties: type: type: string enum: - authorization_error - validation_error - not_found - rate_limited - server_error - not_implemented description: The category of error that occurred message: type: string description: Human-readable error message docs_url: type: string format: uri description: Link to relevant documentation request_id: type: string description: Unique request identifier for debugging required: - type - message description: Error details required: - error description: Standard error response format example: error: type: authorization_error message: Authentication required '404': description: Resource not found content: application/json: schema: type: object properties: error: type: object properties: type: type: string enum: - authorization_error - validation_error - not_found - rate_limited - server_error - not_implemented description: The category of error that occurred message: type: string description: Human-readable error message docs_url: type: string format: uri description: Link to relevant documentation request_id: type: string description: Unique request identifier for debugging required: - type - message description: Error details required: - error description: Standard error response format example: error: type: not_found message: Resource not found '429': description: Rate limit exceeded content: application/json: schema: type: object properties: error: type: object properties: type: type: string enum: - authorization_error - validation_error - not_found - rate_limited - server_error - not_implemented description: The category of error that occurred message: type: string description: Human-readable error message docs_url: type: string format: uri description: Link to relevant documentation request_id: type: string description: Unique request identifier for debugging required: - type - message description: Error details required: - error description: Standard error response format example: error: type: rate_limited message: Rate limit exceeded security: - apiKey: [] components: securitySchemes: apiKey: type: apiKey in: header name: Authorization description: >- API key must be prefixed with "Key ", e.g. Authorization: Key YOUR_API_KEY ````