Compound Interest Calculator – Future Value and Interest
Use this free compound interest calculator to see how a lump sum grows when interest is compounded at regular intervals. Enter principal, annual rate, years and compounding frequency (yearly, quarterly, monthly or daily). The tool shows future value and total interest—useful for fixed deposits, savings and one-time investments. No sign-up, runs in your browser.
Compound Interest Calculator
See how your savings or investments may grow when interest is added back to the principal on a regular schedule such as yearly, quarterly or monthly.
How the compound interest formula works
When interest is added to the principal at regular intervals, the next period's interest is earned on the new balance. The formula is:
FV = P × (1 + r/n)n×t
- P = principal (initial amount)
- r = annual interest rate (decimal, e.g. 0.07 for 7%)
- n = compounding frequency per year (1, 4, 12 or 365)
- t = number of years
Total interest = future value − principal. Higher n (e.g. monthly vs yearly) means interest is added more often, so FV is slightly higher for the same rate and tenure.
Understanding compound interest and when to use this calculator
Compound interest means you earn interest not only on your original amount but also on the interest that has already been added. So your balance grows faster over time than with simple interest, where only the principal earns interest. Fixed deposits, savings accounts and many investments use compounding—often quarterly or monthly—and this calculator lets you see how much you could have at the end of a given period and how much of that is interest.
You enter the principal (the amount you invest or deposit), the annual interest rate, the number of years and how often interest is compounded per year. Choosing "monthly" means 12 times a year; "daily" means 365. The more frequently interest is compounded, the higher the future value for the same rate and tenure, because each time interest is added, the next period's interest is calculated on a larger balance. Use the frequency that matches your product—for example, quarterly for many FDs and monthly for many savings accounts.
This calculator is for a single lump sum: you put in a fixed amount once and let it grow. If you add money regularly (e.g. every month), use the SIP calculator instead, which models a series of contributions. The lumpsum calculator on this site assumes yearly compounding; the compound interest calculator here gives you the flexibility to choose the compounding frequency, so you can model FDs and other products that compound at different intervals.
The calculator runs in your browser and does not store your inputs. You can try different rates, tenures and frequencies to compare scenarios. Remember that the result is a projection: actual returns depend on the product, market conditions, taxes and fees. Use the output as a planning aid, not a guarantee. Read the product's terms and, if needed, seek advice from a qualified financial adviser before investing.