# Compound Interest Future Value Calculator

> Compound Interest Future Value Calculator is a paid API for AI agents from agent402.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

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.

## Facts

- Endpoint: POST https://agent402.tools/api/compound-interest
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/compound-interest-future-value-calculator-64a1bc4b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ukkbTpOoPwIdkS-1YM3ZX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability compound-interest-future-value-calculator-64a1bc4b -d '<json body>'
```

Example prompt: 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?

## When to prefer this

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.

## Known failure modes

- 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

## How this service works

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.

## Output

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.

## Request schema (JSON Schema)

```json
{
 "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."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "periods": 120,
  "futureValue": 1647.01,
  "totalInterest": 647.01,
  "effectiveAnnualRate": 0.051162
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/compound-interest-future-value-calculator-64a1bc4b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)