> ## Documentation Index > Fetch the complete documentation index at: https://docs.creem.io/llms.txt > Use this file to discover all available pages before exploring further. # Preview an unsaved meter definition > Dry-run a candidate meter definition against your real usage over the last 7 whole UTC days (today included, future-dated events excluded) WITHOUT creating anything: matched events, aggregated units, distinct customers, and a zero-filled per-day series, oldest first. Useful for checking a definition before committing to it. The scan is capped defensively and runs newest-first, so a very high-volume store gets the most recent slice of the window rather than an unbounded scan — the recent days stay complete and the oldest day of the series degrades. ## OpenAPI ````yaml post /v1/meters/preview openapi: 3.0.0 info: title: Creem API description: >- Creem is an all-in-one platform for managing subscriptions and recurring revenue, tailored specifically for today's SaaS companies. It enables you to boost revenue, enhance customer retention, and scale your operations seamlessly. version: v1 contact: name: Creem Support url: https://creem.io email: support@creem.io license: name: Commercial url: https://creem.io/terms termsOfService: https://creem.io/terms servers: - url: https://api.creem.io description: Production — live API for processing real transactions and data. x-speakeasy-server-id: prod - url: https://test-api.creem.io description: Test — sandbox API for development and testing with no real charges. x-speakeasy-server-id: test security: [] tags: [] externalDocs: description: Creem Documentation url: https://docs.creem.io paths: /v1/meters/preview: post: tags: - Meters summary: Preview an unsaved meter definition description: >- Dry-run a candidate meter definition against your real usage over the last 7 whole UTC days (today included, future-dated events excluded) WITHOUT creating anything: matched events, aggregated units, distinct customers, and a zero-filled per-day series, oldest first. Useful for checking a definition before committing to it. The scan is capped defensively and runs newest-first, so a very high-volume store gets the most recent slice of the window rather than an unbounded scan — the recent days stay complete and the oldest day of the series degrades. operationId: previewMeter parameters: [] requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/PreviewMeterApiRequestDto' responses: '200': description: Preview of the candidate definition content: application/json: schema: $ref: '#/components/schemas/MeterPreviewApiResponseDto' '400': description: Bad Request - Invalid input parameters '401': description: Unauthorized - Invalid or missing API key '404': description: Not Found - Resource does not exist '422': description: The candidate definition is not satisfiable content: application/json: schema: $ref: '#/components/schemas/UsageMeteringErrorApiResponseDto' security: - ApiKey: [] components: schemas: PreviewMeterApiRequestDto: type: object properties: event_name: type: string description: The usage event name the candidate meter would consume example: image.generated aggregation: type: string description: Aggregation to dry-run enum: - count - sum - average - min - max - unique example: count aggregation_property: type: string description: >- Event property the aggregation reduces. Required for every aggregation except "count". example: tokens filter: description: Optional filter to dry-run alongside the aggregation allOf: - $ref: '#/components/schemas/MeterFilterApiRequestDto' unit_label: type: string description: >- Display unit for the preview. Cosmetic (nothing is persisted); defaults to "units". example: images default: units required: - event_name - aggregation MeterPreviewApiResponseDto: type: object properties: matched_events: type: number description: Events the meter would count over the preview window example: 137 units: type: string description: >- Aggregated units over the whole window, as a string for BigInt safety example: '4820' distinct_customers: type: number description: Distinct customers among the matching events example: 12 daily: description: The last 7 UTC days (today included), oldest first and zero-filled type: array items: $ref: '#/components/schemas/MeterPreviewDailyApiResponseDto' required: - matched_events - units - distinct_customers - daily UsageMeteringErrorApiResponseDto: type: object properties: error: description: Error details allOf: - $ref: '#/components/schemas/UsageMeteringErrorDetailApiDto' required: - error MeterFilterApiRequestDto: type: object properties: conjunction: type: string description: How the clauses combine enum: - and - or example: and clauses: description: >- Filter clauses. An empty list means the meter counts every event with the given event name. type: array items: $ref: '#/components/schemas/FilterClauseApiRequestDto' required: - conjunction - clauses MeterPreviewDailyApiResponseDto: type: object properties: date: type: string description: UTC calendar day example: '2026-08-16' event_count: type: number description: Matching events on this day example: 42 value: type: string description: >- The aggregation folded over this day alone, as a string for BigInt safety example: '1280' required: - date - event_count - value UsageMeteringErrorDetailApiDto: type: object properties: type: type: string description: Error category enum: - invalid_request_error - api_error - authentication_error - rate_limit_error example: invalid_request_error code: type: string description: Machine-readable error code example: meter_name_taken nullable: true message: type: string description: Human-readable error message example: A meter named "Image generations" already exists in this store param: type: string description: The parameter related to the error, if applicable example: events[3].customer_id nullable: true details: type: object description: >- Structured, machine-readable context for errors that support an action, omitted entirely when there is none. Currently emitted for `meter_name_taken` when the colliding name is held by an ARCHIVED meter: `archived_holder` is true and `archived_holder_id` is that meter, which can be restored via POST /v1/meters/{id}/unarchive. Additive — treat unknown keys as ignorable. example: archived_holder: true archived_holder_id: mtr_abc123 request_id: type: string description: Unique request identifier for support example: req_abc123def456 required: - type - code - message - request_id FilterClauseApiRequestDto: type: object properties: property: type: string description: >- Event property to test. Resolved as a top-level property first, then as a metadata key — never prefixed with "metadata.". example: tier operator: type: string description: Comparison operator enum: - equals - not_equals - gt - gte - lt - lte - contains - not_contains example: equals value: description: >- Value to compare against. Auto-parsed (number → boolean → string) on both sides before comparison, so "10" and 10 behave the same — which is why a raw number or boolean is accepted here as well as a string. example: pro oneOf: - type: string - type: number - type: boolean required: - property - operator - value securitySchemes: ApiKey: type: apiKey in: header name: x-api-key description: >- API key for authentication. You can find your API key in the Creem dashboard under Settings > API Keys. ````