# Compound Interest Calculator

> Project investment growth with regular monthly contributions and selectable compounding.

Page: https://askcalculators.com/calculator/compound-interest-calculator/
Definition: https://askcalculators.com/calculator/compound-interest-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/compound-interest-calculator/schema.json
Version: 20.1.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/compound-interest-calculator/?initial=10000&monthly=500&annualRate=7&years=20&frequency=12

## Inputs
- initial: Initial investment; type=money; required; default=10000; min=0
- monthly: Monthly contribution; type=money; optional; default=500; min=0
- annualRate: Annual return; type=percent; required; default=7; min=0; max=30
- years: Years; type=number; required; default=20; min=1; max=80
- frequency: Compounding; type=select; required; default=12; values=12|4|1|365

## Outputs
- futureValue: Future value; format=currency; primary
- contributions: Total contributions; format=currency
- interestEarned: Growth earned; format=currency
- growthPercent: Growth on contributions; format=percent

## Formula
FV = P(1 + r/m)ᵐᵗ + PMT × [((1 + i)ⁿ − 1) ÷ i]

- P: initial investment
- PMT: monthly contribution
- r: annual rate
- m: compounding periods per year
- i: equivalent monthly rate

Monthly contributions are added at the end of each month.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.