Compound Interest Calculator: investment calculator with monthly contribution

Three calculator modes in one page

Invest mode projects growth with initial capital, monthly deposits, rate frequency, and period frequency. Results include final amount, total invested, and total interest.

Goal mode solves the monthly contribution needed to reach a final target. Required-rate mode estimates the monthly and yearly rate needed to hit a specific amount.

Practical financial planning outputs

The interface includes growth chart, detailed monthly/yearly table, text summary, CSV export, and shareable URL for scenario collaboration.

You can also compare simple versus compound interest and optionally apply annual inflation to inspect nominal vs real purchasing power.

• Automatic conversion between monthly and yearly rates.
• Contribution timing toggle (period start or end).
• Detailed rows with opening balance, contribution, interest, and closing balance.
• Quick-copy summary for reports and discussion.

Important interpretation limits

Projected values are mathematical estimates and do not account for taxes, platform fees, asset volatility, or credit risk unless modeled separately.

Use multiple scenarios with conservative and optimistic rates to make planning decisions with better risk awareness.