# Compound Savings Calculator API

> For the complete documentation index, see [llms.txt](/llms.txt).

Project savings growth with compound interest and regular contributions.

Use this endpoint to add the tool to your app, site, workflow, or agent without rebuilding formulas, validation, examples, and docs.

- Slug: `compound-savings-calculator`
- Category: `finance`
- Version: `2026-04-22`
- Credits per successful call: 1
- Starts on: free
- Max payload: 65536 bytes
- Privacy mode: `hash_only`
- Available on: free, starter, pro, business, scale
- Browser tool: https://miniwebtool.com/compound-savings-calculator/

## Endpoint

`POST https://api.miniwebtool.com/v1/tools/compound-savings-calculator/run`

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `initial_balance` | `float` | no |  |
| `contribution` | `float` | no |  |
| `contribution_frequency` | `str` | no | 1 | 2 | 4 | 12 | 26 | 52 | 365 Choices: 1, 2, 4, 12, 26, 52, 365 |
| `annual_rate_percent` | `float` | no |  |
| `compound_frequency` | `str` | no | 1 | 2 | 4 | 12 | 26 | 52 | 365 Choices: 1, 2, 4, 12, 26, 52, 365 |
| `years` | `int` | no |  |
| `inflation_rate_percent` | `float` | no |  |
| `precision` | `int` | no |  |

## Example request

```json
{
  "initial_balance": 10000,
  "contribution": 500,
  "contribution_frequency": "12",
  "annual_rate_percent": 6,
  "compound_frequency": "12",
  "years": 10,
  "inflation_rate_percent": 0,
  "precision": 2
}
```

## cURL

```bash
curl -X POST https://api.miniwebtool.com/v1/tools/compound-savings-calculator/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"initial_balance":10000,"contribution":500,"contribution_frequency":"12","annual_rate_percent":6,"compound_frequency":"12","years":10,"inflation_rate_percent":0,"precision":2}'
```

## Response envelope

```json
{
  "request_id": "01K...",
  "tool": "compound-savings-calculator",
  "tool_version": "2026-04-22",
  "credits_used": 1,
  "result": {}
}
```

## Errors

Errors are RFC 7807 `application/problem+json`. Branch on `code`, not `title`.

## MCP

Agents can discover and call this tool through `https://api.miniwebtool.com/mcp` or `https://api.miniwebtool.com/v1/mcp` using MCP `tools/list` and `tools/call`.

## Frequently asked

### What does the Compound Savings Calculator API do?

Project savings growth with compound interest and regular contributions. Use it to add this utility without rebuilding formulas, validation, examples, and documentation.

### How much does one call cost?

1 credit per successful call. Failed calls do not bill.

### What parameters are required?

Required fields: (none). Full schema at `https://api.miniwebtool.com/v1/openapi.json`.

### Is this deterministic?

Yes. Same input, same output. Tool version: 2026-04-22.