Compound Interest Calculator
See how money grows when interest earns interest. Choose how often interest compounds, and optionally add a fixed amount every month.
Investment details
Your result
Growth year by year
Year-wise growth
The compound interest formula
A = P × (1 + r/n)n × t
With monthly additions, each contribution also compounds from the month it is added. The calculator converts your compounding frequency to an equivalent monthly rate so the two combine exactly.
Example: ₹1,00,000 at 10% compounded yearly for 10 years becomes ₹2,59,374, compared with ₹2,00,000 under simple interest.
Frequently asked questions
Does more frequent compounding make a big difference?
It helps, but less than people expect. Moving from yearly to monthly compounding at 10% raises the effective yearly rate from 10% to about 10.47%. Time and rate matter far more.
What is the rule of 72?
Divide 72 by the annual rate to estimate how many years it takes money to double. At 8%, money doubles in about 9 years.