Compound Interest Calculator

Simulate the growth of your investment with compound interest, including periodic contributions.

How does it work?

Compound interest makes your earnings generate more earnings: the balance grows faster over time. That is why starting early matters more than contributing a lot.

Enter your initial balance, annual contribution, expected rate and years, and see the year-by-year growth.

Frequently asked questions

What is compound interest?

It is reinvesting the interest so the next period is calculated on a larger balance. Unlike simple interest, growth accelerates over time.

What annual return should I expect?

It depends on the product: a savings account may offer 2–4%, while broadly diversified stock index funds have historically returned around 7% annualized over the long run, with swings along the way.

Do periodic contributions matter a lot?

Yes, enormously: contributing every year grows both the balance and the base for future interest. Try setting the contribution to zero and see the difference.

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