{"uid":"cap_8zxpMg7O2yn0mynBB2VmX","slug":"finance-calculators-loan-payment-amortization-87ec4b25","name":"Finance Calculators – Loan Payment & Amortization","description":"Loan payment, total interest and amortization preview from principal, annual rate and term, monthly or other frequency.","url":"https://finance-calculators.x402tookit.com/loan-payment?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["principal","annual_rate_pct","years"],"properties":{"years":{"type":"number","description":"Term in years"},"principal":{"type":"number","description":"Amount borrowed"},"annual_rate_pct":{"type":"number","description":"Annual interest rate in percent, e.g. 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monthly (or custom-frequency) loan payment, total interest, total paid, and an amortization preview given principal, annual rate, and term.","exampleAgentPrompt":"What would my monthly payment be on a $250,000 loan at 6.5% annual interest over 30 years, and how much total interest would I end up paying?","exampleUseCases":[{"title":"Monthly mortgage payment estimate","prompt":"I'm looking at a home priced at $450,000 and putting 20% down, financing the rest at 7.1% over 30 years — what's my monthly mortgage payment and how much interest will I pay over the life of the loan?"},{"title":"Car loan total cost check","prompt":"If I borrow $28,000 for a car at 5.9% annual interest for 5 years with monthly payments, what will my payment be and how much will I pay in interest overall?"},{"title":"Bi-weekly payment comparison","prompt":"Calculate the payment on a $180,000 student loan consolidation at 4.5% over 20 years using 26 payments per year instead of monthly — I want to see the total interest and what the first and last payments look like."}],"resultDescription":"Returns a structured object with: the periodic payment amount, total number of payments, total amount paid, total interest paid, interest as a percentage of principal, a human-readable summary, a disclaimer, and an array showing the first and last amortization entries (with balance, payment, interest, and principal components for each).","failureModes":["Missing required parameters (principal, annual_rate_pct, years) returns an error","Non-positive or zero principal or rate may yield invalid results","Extremely short terms or very high rates may produce edge-case outputs","Network or payment (x402) authentication failure results in no response","payments_per_year of 0 or negative would cause division errors"],"whenToPreferThis":"Choose this endpoint when you need a quick, accurate loan payment and total-interest estimate with an amortization preview — especially when the user supplies principal, rate, and term and wants both the periodic payment and the full interest cost. It supports non-monthly payment frequencies (bi-weekly, etc.) which many simple calculators omit. Prefer this over general financial APIs when you specifically need amortization breakdown data alongside the payment figure.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-31T00:30:23.294Z","isFirstParty":false,"canonicalSlug":"finance-calculators-loan-payment-amortization-87ec4b25"}