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

# Term Structure Volatility

> Query a term structure (expiry-dependent) volatility surface where volatility varies by expiry but is constant across strikes. Interpolates between provided expiry points. Useful for modeling volatility term structure for ATM options or when strike dependency is negligible. [Tier: PRO, Credits: 5]



## OpenAPI

````yaml api-specs/volatility.json post /quantlib/volatility/surface/term-structure
openapi: 3.1.0
info:
  title: FinceptQuantLib API - Volatility
  description: >-
    Volatility module endpoints for FinceptQuantLib API. Standard Tier module (2
    credits per request) providing comprehensive volatility surface modeling,
    SABR model calibration and analytics, and local volatility calculations for
    derivatives pricing and risk management.
  version: 3.0.0
  contact:
    name: Fincept API Support
    url: https://fincept.in
servers:
  - url: https://api.fincept.in
    description: Fincept API Production Server
security:
  - APIKeyHeader: []
tags:
  - name: quantlib-volatility
    description: >-
      Volatility surface modeling, SABR calibration, and local volatility
      calculations
    x-displayName: Volatility
paths:
  /quantlib/volatility/surface/term-structure:
    post:
      tags:
        - quantlib-volatility
      summary: Term Structure Volatility
      description: >-
        Query a term structure (expiry-dependent) volatility surface where
        volatility varies by expiry but is constant across strikes. Interpolates
        between provided expiry points. Useful for modeling volatility term
        structure for ATM options or when strike dependency is negligible.
        [Tier: PRO, Credits: 5]
      operationId: term_structure_vol
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - expiries
                - volatilities
                - query_expiry
              properties:
                expiries:
                  type: array
                  items:
                    type: number
                  description: Array of expiry times in years (must be strictly increasing)
                  example:
                    - 0.25
                    - 0.5
                    - 1
                    - 2
                  minItems: 2
                volatilities:
                  type: array
                  items:
                    type: number
                  description: Array of volatilities corresponding to each expiry
                  example:
                    - 0.22
                    - 0.24
                    - 0.25
                    - 0.23
                  minItems: 2
                query_expiry:
                  type: number
                  description: Expiry time in years for the query (will be interpolated)
                  example: 0.75
                  minimum: 0
            example:
              expiries:
                - 0.25
                - 0.5
                - 1
                - 2
              volatilities:
                - 0.22
                - 0.24
                - 0.25
                - 0.23
              query_expiry: 0.75
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                    example: true
                  data:
                    type: object
                    properties:
                      volatility:
                        type: number
                        description: Interpolated volatility at the query expiry
                        example: 0.245
                      total_variance:
                        type: number
                        description: Total variance at the query expiry
                        example: 0.04501875
                      query_expiry:
                        type: number
                        description: Query expiry (echo of input)
                        example: 0.75
              example:
                success: true
                data:
                  volatility: 0.245
                  total_variance: 0.04501875
                  query_expiry: 0.75
        '401':
          $ref: '#/components/responses/UnauthorizedError'
        '402':
          $ref: '#/components/responses/InsufficientTierError'
        '422':
          $ref: '#/components/responses/ValidationError'
      security:
        - APIKeyHeader: []
components:
  responses:
    UnauthorizedError:
      description: Authentication information is missing or invalid
      content:
        application/json:
          schema:
            type: object
            properties:
              detail:
                type: string
                example: Invalid API key
    InsufficientTierError:
      description: API tier insufficient for this endpoint
      content:
        application/json:
          schema:
            type: object
            properties:
              detail:
                type: string
                example: Endpoint requires Standard tier or higher
    ValidationError:
      description: Validation Error
      content:
        application/json:
          schema:
            type: object
            properties:
              detail:
                type: array
                items:
                  type: object
                  properties:
                    loc:
                      type: array
                      items:
                        type: string
                    msg:
                      type: string
                    type:
                      type: string
          example:
            detail:
              - loc:
                  - body
                  - volatility
                msg: field required
                type: value_error.missing
  securitySchemes:
    APIKeyHeader:
      type: apiKey
      in: header
      name: X-API-Key
      description: >-
        API key for authentication. Get your key at
        https://api.fincept.in/auth/register

````