> ## 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.

# Calculate Forward Rate from Discount Factors

> Calculate the forward interest rate between two future time periods using their discount factors. Forward rates represent the implied future interest rate consistent with the current term structure. Used for FRA pricing, forward curve construction, and understanding market expectations of future rates. The calculation ensures no arbitrage between borrowing/lending at different maturities. [Tier: STANDARD, Credits: 2]



## OpenAPI

````yaml api-specs/solver.json post /quantlib/solver/finance/forward-rate
openapi: 3.1.0
info:
  title: FinceptQuantLib API - Solver
  description: >-
    Solver module endpoints for FinceptQuantLib API. The Solver module (Basic
    Tier, 1 credit per request) provides advanced financial solvers including
    bond analytics (yield, duration, convexity), implied volatility
    calculations, spread computations (Z-spread, ASW, OAS), curve bootstrapping,
    interest rate conversions, and model calibration (Vasicek, CIR). Essential
    for fixed income analysis, 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-solver
    description: >-
      Advanced financial solvers for bond analytics, implied volatility, spread
      calculations, and model calibration
    x-displayName: Solver
paths:
  /quantlib/solver/finance/forward-rate:
    post:
      tags:
        - quantlib-solver
      summary: Calculate Forward Rate from Discount Factors
      description: >-
        Calculate the forward interest rate between two future time periods
        using their discount factors. Forward rates represent the implied future
        interest rate consistent with the current term structure. Used for FRA
        pricing, forward curve construction, and understanding market
        expectations of future rates. The calculation ensures no arbitrage
        between borrowing/lending at different maturities. [Tier: STANDARD,
        Credits: 2]
      operationId: forward_rate
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - df1
                - df2
                - t1
                - t2
              properties:
                df1:
                  type: number
                  description: Discount factor at time t1
                  example: 0.95
                df2:
                  type: number
                  description: Discount factor at time t2
                  example: 0.9
                t1:
                  type: number
                  description: Start time in years
                  example: 1
                t2:
                  type: number
                  description: End time in years
                  example: 2
                compounding:
                  type: string
                  description: Compounding convention for the forward rate
                  default: simple
                  enum:
                    - simple
                    - continuous
                    - annual
                  example: simple
            example:
              df1: 0.95
              df2: 0.9
              t1: 1
              t2: 2
              compounding: simple
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                    example: true
                  data:
                    type: object
                    properties:
                      forward_rate:
                        type: number
                        description: The calculated forward rate as a decimal
                        example: 0.0556
              example:
                success: true
                data:
                  forward_rate: 0.0556
        '401':
          $ref: '#/components/responses/UnauthorizedError'
        '402':
          $ref: '#/components/responses/InsufficientTierError'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                type: object
                properties:
                  detail:
                    type: array
                    items:
                      type: object
      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 Basic tier or higher
  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

````