Interest Calculator
Calculate simple and compound interest: final amount and interest earned for any principal, rate and period.
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Simple vs. Compound Interest
Simple interest is earned on the principal only: A = P × (1 + r × t). Compound interest is earned on the principal plus previously accrued interest: A = P × (1 + r/m)^(m×t), where m is how many times per year interest compounds (yearly, monthly or daily). Over long periods compounding dramatically outperforms simple interest.
Enter your principal, annual rate and duration, choose the compounding frequency, and the tool shows the final amount and total interest instantly.
Frequently Asked Questions
What difference does compounding frequency make?
The more often interest is added to the balance, the sooner it starts earning interest itself. 10,000 at 12% for 5 years grows to 17,623 with annual compounding and 18,167 with monthly compounding.
What is the rule of 72?
A quick estimate of doubling time: divide 72 by the annual rate. At 8% per year, money doubles in roughly 72 ÷ 8 = 9 years with compound interest.
Is tax deducted from the result?
No. The tool shows gross interest. Withholding tax on deposits varies by country and term; subtract your local rate from the interest figure.
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Interest Calculator