Compound interest calculator
How much you will have, how much is interest, and what it is really worth after inflation.
- 100% free
- No sign-up
- Your numbers stay on your device
- Export to CSV and PDF
Enter what you have today, how much you can add each month, the annual rate and the number of years. The calculator shows your final balance, how much you put in and how much is interest, and converts it to today's money by discounting inflation. Compare up to three scenarios (for example, a savings account versus an index fund) on the same chart and download the year-by-year table as CSV or PDF. Everything is calculated in your browser: your numbers are never sent to a server.
How it works
Enter your numbers
Starting amount, monthly or yearly contribution, annual interest rate, years and expected inflation.
Compare scenarios
Add up to two scenarios with a different rate or contribution and see them on the same chart.
Take the result with you
Download the year-by-year table as CSV or PDF, or copy a link with your numbers to open it later.
What makes it different
Three scenarios at once
Compare different rates or contributions on one chart, without opening another tab.
Real value
Discounts inflation so you see what that money will actually buy, not just the number.
In plain words
Besides the table, one sentence that tells you what the result means.
CSV and PDF
The yearly table ready for Excel or Google Sheets, or to save and print.
Private
The math runs in your browser. No account, and your amounts are never stored.
Formula in plain sight
Under the result you see the formula and the assumptions: no black boxes.
What people use it for
Monthly savings
How much you will have if you save a fixed amount every month for 5, 10 or 20 years.
High-yield savings vs index fund
Put each rate in its own scenario and compare the final balance.
College fund
How much to contribute today to reach a goal by a given date.
Retirement
Project your 401(k) or IRA contributions and see their value in today's dollars.
Explaining it to family
Share the link or the PDF to show why starting early matters.
Beating inflation
Check whether a rate actually beats inflation where you live.
Compared with other calculators
Most compound interest calculators give you one number. This one helps you decide:
- Compare up to 3 scenarios on the same chart.
- Shows the real value after inflation, not only the nominal amount.
- Monthly or yearly contributions, at the start or end of each period.
- Export the full table to CSV and PDF without giving your email.
- Available in English, Spanish and Portuguese, in your currency.
Frequently asked questions
How is compound interest calculated with monthly contributions?
Each month the interest is added to the balance and then your contribution, so next month's interest is calculated on a larger balance. With monthly compounding the result matches the future value formula: FV = P·(1+i)^n + A·((1+i)^n − 1)/i, where i is the monthly rate and n the number of months.
How much will I have if I save $100 a month for 10 years at 8%?
About $18,295, of which $12,000 are your contributions and $6,295 is interest (monthly compounding, contribution at the end of each month). Starting with $1,000 you would reach about $20,514.
What is the real value after inflation?
It is your final balance expressed in today's money: what that amount would buy today. It is calculated by dividing the balance by (1 + inflation)^years. If your rate is lower than inflation, the real value can be lower than what you put in.
Which rate should I enter: APR or APY?
Enter the annual rate your bank quotes and pick the matching compounding. An APY is already an effective yearly rate, so use yearly compounding; an APR compounded monthly should use monthly compounding.
Is daily compounding the same as monthly?
Almost. With the same nominal rate, daily compounding earns slightly more than monthly, and monthly slightly more than yearly. The difference is small at low rates and grows with high rates and long periods.
Does the calculator store my data?
No. The calculation runs in your browser and nothing is sent to a server. To see it again, use Copy link: your numbers travel inside the link itself and never reach our server.
Can I use the result as investment advice?
No. It is a projection with a fixed rate you choose; real investments go up and down and have fees and taxes. Use it to compare scenarios and confirm the terms with your provider.