Compound Interest Calculator
Estimate how your money grows over time using compound interest, with optional monthly contributions.
Expected annual return. Compounded monthly.
Added at the end of each month.
| Year | Total value | Total contributions | Total interest |
|---|
Informational only. Estimates do not include inflation, taxes, or fees.
How it works
Compound interest means your investment earns interest not only on the original amount but also on previously earned interest.
This tool simulates growth month by month using a monthly rate (annual rate ÷ 12) and optionally adds contributions at the end of each month.
How to interpret results:
- Final value: total accumulated amount
- Total contributions: how much you invested
- Total interest: growth generated by compounding
Over time, interest becomes a larger portion of total growth. This is why long-term investing significantly increases returns.
Examples
- Long-term investing: Compare 10 vs 30 years to see exponential growth.
- Monthly savings plan: Add a fixed monthly contribution to simulate regular investing.
- Goal planning: Estimate how much you need to invest to reach a target amount.
Example:
- $10,000 at 7% for 10 years → grows to about $19,671
- $10,000 + $200/month → significantly higher due to contributions
When to use this tool
This tool is designed for quick, practical tasks such as everyday calculations, data formatting, or simple conversions. It is best used when you need fast results without installing software or using complex tools.
When to use
- Quick checks or one-time calculations
- Validating or converting data before using it elsewhere
- Simple tasks that do not require advanced software
When not to use
- Critical financial, legal, or medical decisions
- Large-scale or automated processing
- Situations requiring guaranteed precision beyond basic validation
Always review results before using them in important contexts.
About this tool
This tool helps you perform quick utility operations directly in your browser. It runs entirely in your browser without sending data to a server.
You can use this tool when handling simple tasks without installing additional software. The results should be interpreted as a processed output based on your input data.
FAQ
- Does this assume monthly compounding?
Yes. This calculator compounds monthly and optionally adds a contribution at the end of each month.
- When are contributions added?
Monthly contributions are added at the end of each month, after interest is applied.
- What does the final value represent?
Final value is the total investment amount after compounding, including both your contributions and earned interest.
- Why is long-term growth so large?
Because compound interest grows exponentially over time. The longer the period, the more interest earns additional interest.
- Does this include inflation or taxes?
No. This is a simplified projection. Real-world returns may differ due to inflation, taxes, and fees.
- Is my data stored?
No. All calculations run locally in your browser.