📉 Compound Interest Calculator
Calculate compound growth with recurring monthly contributions and a year-by-year balance schedule.
Try the calculator
The values below are a working example. Change any field to recalculate instantly in your browser.
Projection assumes a constant rate and regular monthly contributions. Taxes, fees, and rate changes are not included.
Year-by-year growth schedule
| Year | Contributions | Interest | Balance |
|---|---|---|---|
| 1 | $100,000.00 | $8,299.95 | $108,299.95 |
| 2 | $100,000.00 | $17,288.79 | $117,288.79 |
| 3 | $100,000.00 | $27,023.71 | $127,023.71 |
| 4 | $100,000.00 | $37,566.61 | $137,566.61 |
| 5 | $100,000.00 | $48,984.57 | $148,984.57 |
| 6 | $100,000.00 | $61,350.22 | $161,350.22 |
| 7 | $100,000.00 | $74,742.21 | $174,742.21 |
| 8 | $100,000.00 | $89,245.72 | $189,245.72 |
| 9 | $100,000.00 | $104,953.02 | $204,953.02 |
| 10 | $100,000.00 | $121,964.02 | $221,964.02 |
Formula & Mathematical Logic
Balance = Principal Growth + Future Value of Monthly Contributions
Computes exact mathematical outputs locally on your device with 0 network latency.
Step-by-Step Worked Example
Sample Scenario
A $10,000 principal at 5% annual interest compounded monthly for 5 years grows to $12,833.59 without additional deposits. Adding $100 at the end of each month produces a higher projected balance because each contribution earns interest for its remaining time.
Frequently Asked Questions (FAQ)
How does the Compound Interest Calculator work?
The calculator applies the selected compounding frequency to the principal, adds optional monthly deposits at the chosen timing, and builds the yearly schedule locally in your browser.
Is my personal or financial data private?
Yes. Calcixa operates on a 100% privacy-first zero-backend architecture. No data leaves your device.
CALCIXA PRACTICAL GUIDE
How to use the Compound Interest Calculator
Compound interest adds earned interest to the balance so later periods calculate growth on the starting principal, earlier interest, and any recurring contributions already deposited. Use this calculator to compare monthly, quarterly, semiannual, annual, or daily compounding and to model optional monthly deposits.
The projection uses a constant nominal annual rate and converts the selected compounding convention into an equivalent monthly growth rate when contributions are included. Real deposits and investments may apply tiered rates, daily balances, taxes, fees, changing rates, or different contribution posting dates.
Step-by-step
- Enter the initial principal and nominal annual interest rate.
- Choose monthly, quarterly, semiannual, annual, or daily compounding.
- Add an optional monthly contribution and choose whether it is deposited at the beginning or end of each month.
- Review the ending balance, effective annual yield, total contributions, interest, and year-by-year schedule.
How to read the result
- Projected balance includes the starting principal, recurring deposits, and accumulated interest.
- Interest earned is separated from all contributions so growth is not mistaken for money deposited.
- The year-by-year schedule shows how time changes the contributions, interest, and balance under the same assumptions.
Common mistakes to avoid
- Confusing annual percentage yield with the nominal annual rate.
- Treating a constant-rate projection as a guaranteed investment return.
- Ignoring contribution timing, fees, taxes, rate changes, and withdrawal restrictions.
Important: This educational estimate is not financial, investment, tax, or lending advice.
More questions about Compound Interest Calculator
Is monthly compounding twelve times the annual return?
No. The annual nominal rate is divided across periods, and each period builds on the balance from the previous one.
Beginning or end-of-month contributions?
A beginning-of-month contribution receives one additional month of modeled growth, so it produces a slightly higher balance when the rate is positive.
What does semiannual compounding mean?
Interest is applied twice per year. It is also commonly called half-yearly compounding.
Sources and methodology
Calcixa explains the model, assumptions, and limitations so you can verify the result. See our calculation and tool methodology for rounding, privacy, testing, and correction practices.
Maintained by the Calcixa product team. This page was last updated on 7 September 2026.