{"uid":"cap_ukkbTpOoPwIdkS-1YM3ZX","slug":"compound-interest-future-value-calculator-64a1bc4b","name":"Compound Interest Future Value Calculator","description":"Compute future value of a principal under compound interest. Returns future value, total interest earned, and the effective annual rate (APY) given the compounding frequency. Matches Excel's FV(rate, nper, 0, -principal) and the classic (1+r/n)^(nt) textbook formula.","url":"https://agent402.tools/api/compound-interest","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"years":{"type":"number","description":"Time horizon in years"},"principal":{"type":"number","description":"Starting amount (positive)"},"annualRate":{"type":"number","description":"Annual interest rate as decimal (0.05 = 5%)"},"compoundingPerYear":{"type":"number","description":"Compounding periods per year (1 = annual, 12 = monthly, 365 = daily). Default 12."}}},"responseSchema":{"type":"json","example":{"periods":120,"futureValue":1647.01,"totalInterest":647.01,"effectiveAnnualRate":0.051162}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_aolugjgYsiNCzzo1ADVPl","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the future value, total interest earned, and effective annual rate (APY) of a principal amount under compound interest for a given rate, time horizon, and compounding frequency.","exampleAgentPrompt":"If I invest $10,000 at an annual rate of 5% compounded monthly for 7 years, what will the future value be, how much interest will I have earned, and what's the effective APY?","exampleUseCases":null,"resultDescription":"Returns the future value of the principal, total interest earned over the period, and the effective annual percentage yield (APY) reflecting the compounding frequency. Matches Excel's FV(rate, nper, 0, -principal) formula.","failureModes":["Missing required fields (principal, annualRate, years) returns a validation error","Negative principal or rate values may produce unexpected results","compoundingPerYear of 0 or negative will cause a division-by-zero or invalid computation","Extremely large time horizons or rates may produce overflow or imprecise floating point results"],"whenToPreferThis":"Use this endpoint when you need a precise, formula-correct compound interest calculation — including future value, interest earned, and APY — that matches Excel's FV function output. Prefer this over generic calculators when APY (effective annual rate) is also needed alongside the future value.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T19:14:06.934Z","isFirstParty":false}