Compound Interest Calculator (contributions, compounding, yearly chart)
Project the balance and interest from a principal, annual rate, period, compounding (yearly to daily) and monthly or yearly contributions, with a year-by-year chart and table. Assumes a fixed rate; not investment advice.
- Runs in your browser (no upload)
The projection assumes the rate stays the same every year.
Result
Contributions made between compounding dates earn simple interest (the annual rate ÷ 12 per month) until the next compounding date. Daily compounding uses a 365-day year with calendar month lengths (February = 28 days). Calculations carry 40 decimal places; only displayed amounts are rounded to the smallest unit.
- Principal + contributions
- Interest
Year 10: balance 41,441.82 (principal + contributions 34,000.00, interest 7,441.82)
Year by year
| Year | Added that year | Interest that year | Total contributed | Total interest | Balance at year end |
|---|---|---|---|---|---|
| Year 1 | 2,400.00 | 337.44 | 12,400.00 | 337.44 | 12,737.44 |
| Year 2 | 2,400.00 | 420.69 | 14,800.00 | 758.13 | 15,558.13 |
| Year 3 | 2,400.00 | 506.50 | 17,200.00 | 1,264.63 | 18,464.63 |
| Year 4 | 2,400.00 | 594.89 | 19,600.00 | 1,859.52 | 21,459.52 |
| Year 5 | 2,400.00 | 685.99 | 22,000.00 | 2,545.51 | 24,545.51 |
| Year 6 | 2,400.00 | 779.85 | 24,400.00 | 3,325.36 | 27,725.36 |
| Year 7 | 2,400.00 | 876.57 | 26,800.00 | 4,201.93 | 31,001.93 |
| Year 8 | 2,400.00 | 976.23 | 29,200.00 | 5,178.16 | 34,378.16 |
| Year 9 | 2,400.00 | 1,078.92 | 31,600.00 | 6,257.08 | 37,857.08 |
| Year 10 | 2,400.00 | 1,184.74 | 34,000.00 | 7,441.82 | 41,441.82 |
How to use
- Enter the starting amount, the annual rate you assume and the number of years, and choose how often interest compounds.
- To add money regularly, enter the contribution, how often (monthly or yearly) and when (at the start or end of each period).
- See the final balance, total contributions, total interest and the effective annual rate, plus a year-by-year chart and table you can download as CSV.
FAQ
What is the difference between compound and simple interest?
Simple interest is paid on the principal only. With compound interest the interest is added to the balance and earns interest itself, so the gap grows over time.
Does compounding more often make a difference?
Slightly: at the same nominal rate, more frequent compounding gives a higher effective annual rate (3% compounded monthly is about 3.0416% a year). The result shows the effective rate.
Will my money really grow like this?
Not necessarily. This is a projection that assumes a constant rate. Real returns vary with markets and products and can be negative. It is not investment advice.
Notes & limitations
- What you enter is processed only on this page and is not sent to YUCTS servers.
- A projection that assumes the same rate every year; it does not guarantee future results and is not investment advice.
- Taxes, fees and inflation are not included.
- Contributions made between compounding dates earn simple interest until the next compounding date; daily compounding uses a 365-day year. Banks and funds may calculate and round interest differently.
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