> ## 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.

# Calibrate SABR Model

> Calibrate SABR model parameters (alpha, beta, rho, nu) to match market volatilities across strikes. Uses optimization to find the best-fit SABR parameters that reproduce market smile. Beta can be fixed or calibrated. Supports multiple optimization methods and custom weighting. Essential for building market-consistent volatility surfaces. [Tier: PRO, Credits: 5]



## OpenAPI

````yaml api-specs/volatility.json post /quantlib/volatility/sabr/calibrate
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/sabr/calibrate:
    post:
      tags:
        - quantlib-volatility
      summary: Calibrate SABR Model
      description: >-
        Calibrate SABR model parameters (alpha, beta, rho, nu) to match market
        volatilities across strikes. Uses optimization to find the best-fit SABR
        parameters that reproduce market smile. Beta can be fixed or calibrated.
        Supports multiple optimization methods and custom weighting. Essential
        for building market-consistent volatility surfaces. [Tier: PRO, Credits:
        5]
      operationId: sabr_calibrate
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - forward
                - expiry
                - strikes
                - market_vols
              properties:
                forward:
                  type: number
                  description: Forward price of the underlying
                  example: 100
                  minimum: 0
                expiry:
                  type: number
                  description: Time to expiry in years
                  example: 1
                  minimum: 0
                strikes:
                  type: array
                  items:
                    type: number
                  description: Array of market strike prices
                  example:
                    - 90
                    - 95
                    - 100
                    - 105
                    - 110
                  minItems: 3
                market_vols:
                  type: array
                  items:
                    type: number
                  description: Array of market implied volatilities for each strike
                  example:
                    - 0.27
                    - 0.26
                    - 0.25
                    - 0.25
                    - 0.26
                  minItems: 3
                beta:
                  type: number
                  description: >-
                    Fixed beta value (if provided, beta is not calibrated).
                    Common: 0 (normal), 0.5 (CIR), 1 (lognormal)
                  example: 0.5
                  minimum: 0
                  maximum: 1
                weights:
                  type: array
                  items:
                    type: number
                  description: >-
                    Optional weights for each strike in calibration (e.g.,
                    vega-weighted)
                  example:
                    - 0.8
                    - 1
                    - 1.2
                    - 1
                    - 0.8
                method:
                  type: string
                  description: >-
                    Optimization method: 'least_squares' (default),
                    'nelder_mead', 'powell'
                  default: least_squares
                  enum:
                    - least_squares
                    - nelder_mead
                    - powell
                  example: least_squares
            example:
              forward: 100
              expiry: 1
              strikes:
                - 90
                - 95
                - 100
                - 105
                - 110
              market_vols:
                - 0.27
                - 0.26
                - 0.25
                - 0.25
                - 0.26
              beta: 0.5
              method: least_squares
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                    example: true
                  data:
                    type: object
                    properties:
                      alpha:
                        type: number
                        description: Calibrated alpha parameter
                        example: 0.248
                      beta:
                        type: number
                        description: Calibrated or fixed beta parameter
                        example: 0.5
                      rho:
                        type: number
                        description: Calibrated rho parameter
                        example: -0.18
                      nu:
                        type: number
                        description: Calibrated nu parameter
                        example: 0.32
              example:
                success: true
                data:
                  alpha: 0.248
                  beta: 0.5
                  rho: -0.18
                  nu: 0.32
        '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

````