---
title: "Calculate a monthly mortgage payment"
method: POST
path: "/api/v1/calculate-mortgage"
tags: ["calculations"]
---

# Calculate a monthly mortgage payment

`POST /api/v1/calculate-mortgage`

## Request

- Base URL: `https://www.usmortgagecalc.com`
- URL: `https://www.usmortgagecalc.com/api/v1/calculate-mortgage`
- Auth: none declared

Full monthly housing cost for a US mortgage: principal and interest, property tax, homeowners insurance, mortgage insurance and HOA dues, plus lifetime totals and payoff timing. Pass a state name to use that state's average property tax rate. This is the right tool for 'what would my payment be on a $400,000 house'.

## Request body

- object: Full monthly housing cost: principal, interest, taxes, insurance, PMI and HOA.
  - `homePrice` number, required: Purchase price of the home in US dollars.
  - `downPaymentPercent` number: Down payment as a percentage of the purchase price, 0 to 100. Not a dollar amount.
  - `annualInterestRatePercent` number: Annual nominal interest rate as a percentage, for example 6.5 for 6.5%.
  - `loanTermYears` integer: Loan term in years. Most US mortgages are 15 or 30.
  - `loanType` 'conventional' | 'fha' | 'va' | 'usda': Loan programme. Affects mortgage insurance and upfront fees.
  - `annualInsurance` number: Annual homeowners insurance premium in US dollars.
  - `monthlyHoa` number: Monthly homeowners association dues in US dollars.
  - `monthlyExtraPrincipal` number: Additional principal paid each month. Shortens the loan rather than lowering the payment.
  - `state` string: Full US state name, for example "Texas". Used to look up the average property tax rate. Either this or propertyTaxRatePercent is required.
  - `propertyTaxRatePercent` number: Annual property tax as a percentage of home value. Omit and pass `state` instead to use that state's average.

## Response `200`

Calculation result.

- object
  - `data` object: The calculation result.
  - `meta` object
    - `operation` string
    - `computedAt` string, date-time

## Other responses

- `400`: Input failed validation. The message names the offending field.
- `429`: Rate limit exceeded. Retry after the interval in Retry-After.

---

[API](https://skmtc.dev/usmortgagecalc/apis/us-mortgage-calculator-api.md) · [All operations](https://skmtc.dev/usmortgagecalc/apis/us-mortgage-calculator-api/llms.txt) · [OpenAPI document](https://skmtc.dev/usmortgagecalc/apis/us-mortgage-calculator-api/revisions/4439848058a8?raw)