Data & Analytics

Total monthly cost (PITI) estimate

Computes the full monthly housing cost: principal + interest plus property tax, homeowners insurance, and PMI/HOA, so affordability reflects real outlay. When no rate is supplied, the current best market rate for the state is resolved via the decision engine. This route is the single source of truth for the PITI math; the MCP estimate_monthly_cost tool and the consumer app call it.

Authentication required: Pass your API key in the X-API-Key header.

post/v1/monthly-cost

Request

  • Base URL: https://api.rateapi.dev
  • URL: https://api.rateapi.dev/v1/monthly-cost
  • Auth: API key in header X-API-Key

Request body

home_pricenumber

Purchase price in dollars. Required unless loan_amount is given.

down_paymentnumber

Cash down payment in dollars. Default 0.

loan_amountnumber

Optional explicit loan amount; overrides home_price - down_payment.

ratenumber

Annual interest rate (percent). If omitted, best market rate for the state is used.

term_monthsinteger

Loan term in months. Default 360.

statestring

2-letter US state code. Default CA.

property_tax_ratenumber

Annual property tax as % of home value. Default 1.1.

annual_insurancenumber

Homeowners insurance dollars/year. Default max(800, 0.35% of home price).

monthly_hoanumber

HOA dues dollars/month. Default 0.

pmi_ratenumber

Annual PMI as % of loan balance. Default 0.5, applied only when LTV > 80%.

credit_scoreinteger

Optional borrower credit score used for the market-rate lookup.

Example request

{
  "home_price": 500000,
  "down_payment": 50000,
  "rate": 6.5,
  "term_months": 360,
  "state": "CA",
  "property_tax_rate": 1.1,
  "pmi_rate": 0.5,
  "credit_score": 740
}

Response

Full PITI breakdown.

home_pricestring

Purchase price the costs were computed from, formatted as a US dollar string.

loan_amountstring

Loan amount in US dollars.

down_paymentstring

Down payment in US dollars.

ltvstring

Loan-to-value ratio, formatted as a percentage string.

rate_usedstring

The rate the calculation was run at, as an annual percentage.

rate_source'provided' | 'market' | 'fallback'

Where the rate used in this calculation came from: provided if the caller supplied it, market if it was taken from live offers, fallback if neither was available and a default was used.

principal_and_intereststring

Monthly principal and interest, formatted as a US dollar string.

monthly_property_taxstring

Monthly property tax, formatted as a US dollar string.

monthly_insurancestring

Monthly homeowners insurance, formatted as a US dollar string.

monthly_pmistring

Monthly private mortgage insurance, formatted as a US dollar string. Zero when PMI does not apply.

monthly_hoastring

Monthly homeowners-association dues, formatted as a US dollar string.

total_monthly_paymentstring

Everything above added together, formatted as a US dollar string.

pmi_appliesboolean

True when the loan-to-value ratio is high enough to require private mortgage insurance.

annual_totalstring

Twelve months of the total payment, formatted as a US dollar string.

breakdownobject

The same components again, as numbers rather than formatted strings.

assumed_defaultsobject

Values filled in where the caller supplied none, so the result is reproducible.

next_actionsobject[]

Other endpoints or tools that are the natural next step from this result.

disclosuresstring[]

Statements that must be shown to a consumer alongside this result.

Changes

No recorded changes to this operation across all 1 revision of this API.