Calculate simple or compound interest and estimate your final balance over time.
The Numelios Interest Calculator helps estimate how interest can accumulate on a principal amount over time. It can be used to compare simple interest and compound interest scenarios using different rates and time periods.
Interest calculations are useful for understanding borrowing costs, savings growth, and the effect of time and rate changes on a balance.
Simple interest is calculated only on the original principal.
The total amount after interest is added can then be estimated as:
Suppose you have $10,000 earning 5% annually for 3 years using simple interest.
Simple interest is calculated only on the original principal. Compound interest can include previously accumulated interest, allowing the balance to grow at an increasing rate over time.
Use the Compound Interest Calculator to explore compounding frequency, time, and future value in more detail.
The principal is the starting amount on which interest is calculated. A larger principal generally produces more interest.
The rate determines how quickly interest accumulates relative to the principal.
Longer periods allow interest to accumulate for more time, increasing the total amount under most interest structures.
For compound interest, the frequency of compounding affects how often accumulated interest is added to the balance.
Interest can increase a savings balance over time, especially when earnings are compounded and regular contributions are added.
Use the Savings Calculator to estimate how an initial balance, recurring deposits, interest rate, and time horizon may affect future savings.
For borrowing, interest represents part of the cost of using money provided by a lender. Loan payments may include both principal repayment and interest.
The Loan Calculator can estimate regular payments and total interest for a fixed-rate loan. For vehicle financing, use the Auto Loan Calculator .
Interest rates are expressed as percentages. If you need to calculate percentages separately, such as finding a rate change or percentage of a value, use the Percentage Calculator .
Simple interest is calculated using the original principal, interest rate, and time period without adding previous interest to the principal.
Compound interest is calculated on the principal plus previously accumulated interest according to the compounding schedule.
A higher rate generally increases interest earned on savings or interest charged on debt when other assumptions remain unchanged.
Generally yes. A longer period gives interest more time to accumulate, although the exact result depends on the interest method.
Not always. The interest rate represents the rate charged on principal, while APR may include certain additional borrowing costs and can provide a broader measure of loan cost.
This calculator is provided for informational and educational purposes only. Results are estimates and do not constitute financial, lending, investment, or tax advice. Actual rates and terms may differ.