> ## Documentation Index > Fetch the complete documentation index at: https://docs.brudcast.com/llms.txt > Use this file to discover all available pages before exploring further. # Estimate campaign reach and cost > Counts and prices an audience selection without saving anything, so the cost of a send is known while the campaign is still being composed. Returns the reachable recipients overall and per channel, plus the credits the selection would cost and whether the wallet balance covers them. This is a POST and so requires the `campaigns:write` scope even though it changes nothing. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v1/user/campaigns/estimate-recipients openapi: 3.0.0 info: title: Brudcast API version: 1.0.0 servers: - url: https://core-service.prod.brudcast.com description: Production security: [] tags: - name: Analytics x-displayName: Analytics - name: Campaigns x-displayName: Campaigns - name: Contacts x-displayName: Contacts - name: Mailboxes x-displayName: Mailboxes - name: Messages x-displayName: Messages - name: Sender Identities x-displayName: Sender Identities - name: Sending Domains x-displayName: Sending Domains - name: Templates x-displayName: Templates - name: Webhooks x-displayName: Webhooks paths: /api/v1/user/campaigns/estimate-recipients: post: tags: - Campaigns summary: Estimate campaign reach and cost description: >- Counts and prices an audience selection without saving anything, so the cost of a send is known while the campaign is still being composed. Returns the reachable recipients overall and per channel, plus the credits the selection would cost and whether the wallet balance covers them. This is a POST and so requires the `campaigns:write` scope even though it changes nothing. parameters: - in: header name: X-Organization-Id required: false description: >- Required when authenticating with an access token. Optional with an API key, whose own organization binding is authoritative; a value contradicting it is refused with 403. schema: type: string format: uuid requestBody: content: application/json: schema: type: object properties: listIds: type: array items: type: string segmentIds: type: array items: type: string contactIds: type: array items: type: string excludeListIds: type: array items: type: string excludeSegmentIds: type: array items: type: string excludeContactIds: type: array items: type: string channels: type: array items: enum: - email - sms - whatsapp - push additionalProperties: false responses: '200': description: '' content: application/json: schema: $ref: '#/components/schemas/CampaignRecipientEstimateResponse' '401': description: The credential is missing, malformed, revoked or expired content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '403': description: >- The key lacks the scope the endpoint requires, or the organization does not match the credential content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '422': description: The payload or query string failed validation content: application/json: schema: $ref: '#/components/schemas/ValidationErrorResponse' '429': description: >- Rate limit exceeded; retry after the number of seconds in `retryAfter` content: application/json: schema: $ref: '#/components/schemas/RateLimitErrorResponse' security: - apiKey: [] - apiKeyBearer: [] components: schemas: CampaignRecipientEstimateResponse: type: object properties: success: type: boolean example: true message: type: string data: $ref: '#/components/schemas/CampaignRecipientEstimate' required: - success - message - data ErrorResponse: type: object properties: success: type: boolean example: false message: type: string example: Resource not found code: type: string enum: - E_VALIDATION_ERROR - E_UNAUTHORIZED_ACCESS - E_UNAUTHORIZED - E_FORBIDDEN - E_INSUFFICIENT_SCOPE - E_ROW_NOT_FOUND - E_TOO_MANY_REQUESTS - E_BUSINESS_RULE_VIOLATION - E_CAMPAIGN_NOT_SENDABLE - INSUFFICIENT_CREDITS - SUBSCRIPTION_REQUIRED example: E_ROW_NOT_FOUND required: - success - message - code ValidationErrorResponse: type: object properties: success: type: boolean example: false message: type: string example: The payload is invalid code: type: string enum: - E_VALIDATION_ERROR - E_UNAUTHORIZED_ACCESS - E_UNAUTHORIZED - E_FORBIDDEN - E_INSUFFICIENT_SCOPE - E_ROW_NOT_FOUND - E_TOO_MANY_REQUESTS - E_BUSINESS_RULE_VIOLATION - E_CAMPAIGN_NOT_SENDABLE - INSUFFICIENT_CREDITS - SUBSCRIPTION_REQUIRED example: E_VALIDATION_ERROR errors: type: array items: $ref: '#/components/schemas/ValidationErrorItem' required: - success - message - code - errors RateLimitErrorResponse: type: object properties: success: type: boolean example: false message: type: string example: Too many requests code: type: string enum: - E_VALIDATION_ERROR - E_UNAUTHORIZED_ACCESS - E_UNAUTHORIZED - E_FORBIDDEN - E_INSUFFICIENT_SCOPE - E_ROW_NOT_FOUND - E_TOO_MANY_REQUESTS - E_BUSINESS_RULE_VIOLATION - E_CAMPAIGN_NOT_SENDABLE - INSUFFICIENT_CREDITS - SUBSCRIPTION_REQUIRED example: E_TOO_MANY_REQUESTS retryAfter: type: number example: 60 required: - success - message - code - retryAfter CampaignRecipientEstimate: type: object properties: estimatedRecipients: type: number description: Reachable recipients across the requested channels, deduplicated total: type: number description: Repeats `estimatedRecipients` perChannel: type: object additionalProperties: type: integer description: Reachable recipients keyed by channel credits: $ref: '#/components/schemas/CampaignCreditEstimate' required: - estimatedRecipients - total - perChannel - credits ValidationErrorItem: type: object properties: field: type: string example: emailAddress rule: type: string example: email message: type: string example: The emailAddress field must be a valid email address required: - field - rule - message CampaignCreditEstimate: type: object properties: lines: type: array items: $ref: '#/components/schemas/CampaignCreditEstimateLine' description: >- One line per credit-billed channel; subscription-billed channels are omitted totalCredits: type: number balanceCredits: type: number description: The organization wallet's current credit balance sufficient: type: boolean description: Whether the balance covers the total required: - lines - totalCredits - balanceCredits - sufficient CampaignCreditEstimateLine: type: object properties: channel: type: string enum: - email - sms - whatsapp - push rateCredits: type: number description: Credits charged per recipient on this channel estimatedRecipients: type: number credits: type: number description: Rate multiplied by the reach for this channel required: - channel - rateCredits - estimatedRecipients - credits securitySchemes: apiKey: type: apiKey in: header name: X-API-Key description: >- An organization API key, prefixed `bk_live_`. Takes precedence over `Authorization` when both are sent. The key is bound to one organization, and the scopes it was issued with are enforced per endpoint. apiKeyBearer: type: http scheme: bearer bearerFormat: bk_live_... description: >- The same organization API key sent as `Authorization: Bearer bk_live_...`. Accepted only when the value begins with `bk_` and no `X-API-Key` header is present. ````