---
title: "Simple Interest Calculator"
method: POST
path: "/api/v1/tools/simple-interest-calculator"
tags: ["tools"]
---

# Simple Interest Calculator

`POST /api/v1/tools/simple-interest-calculator`

## Request

- Base URL: `https://toolforte.com`
- URL: `https://toolforte.com/api/v1/tools/simple-interest-calculator`
- Auth: HTTP bearer

Interest at a flat rate on the original principal only, I = P x r x t, over a period given in years or months. Returns the interest, the final amount, and what the same money would have made with annual compounding, so the two methods can be compared before signing anything.

## Request body

- object
  - `principal` integer
  - `annualRatePercent` integer
  - `time` integer
  - `timeUnit` string

## Response `200`

Successful result

- object
  - `ok` boolean
  - `data` object
    - `principal` integer
    - `annualRatePercent` integer
    - `time` integer
    - `timeUnit` string
    - `timeYears` integer
    - `interest` integer
    - `totalAmount` integer
    - `compoundTotalAmount` number
    - `compoundInterest` number
    - `compoundAdvantage` number

## Other responses

- `400`: Missing or invalid request fields
- `401`: Invalid or missing API key
- `429`: Monthly plan limit reached

---

[API](https://skmtc.dev/toolforte/apis/toolforte-api.md) · [All operations](https://skmtc.dev/toolforte/apis/toolforte-api/llms.txt) · [OpenAPI document](https://skmtc.dev/toolforte/apis/toolforte-api/revisions/4d814d484dfc?raw)