happytails.ai

Simple interest calculator

Open Simple interest calculator on Happytails.ai. This view has the same page content and links, with explicit tool capabilities. Read the processing notes before using a tool.

Tool capabilities

{
  "id": "simple-interest",
  "category": "finance-tools",
  "built": true,
  "requirements": "Interest is calculated on the starting principal only. Fees, taxes, payment schedules and changing rates are excluded. For interest earned on previous interest, use the Compound interest tool.",
  "implementation": {
    "fields": [
      {
        "key": "principal",
        "label": "Starting amount",
        "value": 1000,
        "type": "number",
        "min": 0,
        "max": 1000000000000000,
        "step": "any"
      },
      {
        "key": "rate",
        "label": "Annual interest (%)",
        "value": 5,
        "type": "number",
        "min": 0,
        "max": 10000,
        "step": "any"
      },
      {
        "key": "years",
        "label": "Years",
        "value": 3,
        "type": "number",
        "min": 0,
        "max": 1000,
        "step": "any"
      }
    ],
    "input": false,
    "live": true,
    "presentation": "metrics",
    "note": "Simple interest = principal × annual rate × years. Interest does not compound. The estimate excludes fees, taxes and changes in rate.",
    "experience": {
      "automatic": true,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.",
      "helpParts": [
        "Change the input or settings to update your result.",
        "Results update as you type.",
        "Up to 1,000,000 characters."
      ],
      "action": null
    },
    "mode": "automatic",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}

Page guide

Calculate interest without compounding.

How to use Simple interest calculator
  1. Enter the values you want to calculate and choose the relevant units or settings.
  2. The result updates as you type. Adjust the available settings if needed.
  3. Review the result, then use Copy result or a download link when available.

Useful next steps

Compound interestPercentagePercentage change

How to use it

Enter the principal, annual percentage rate and number of years. Simple interest is principal × rate × time, with the rate expressed as a decimal.

A worked example

A principal of 1,000 at 5% a year for 3 years earns 150 in simple interest. The final amount is 1,150.

What to know

Interest is calculated on the starting principal only. Fees, taxes, payment schedules and changing rates are excluded. For interest earned on previous interest, use the Compound interest tool.