Our comprehensive interest calculator helps you understand exactly how interest works on your savings, investments, and loans. Calculate simple interest or compound interest with different compounding frequencies. Compare APR vs APY, see how much interest you'll earn on savings accounts or fixed deposits, and understand the true cost of loan interest.
Interest Comparison ($10,000 at 5% for 3 years):
Over 30 years, compound interest at 7% turns $10K into $81K vs $31K with simple interest - that's the power of "interest on interest"!
Year by year comparison of simple vs compound interest
| Year | Simple Interest | Simple Balance | Compound Interest | Compound Balance |
|---|---|---|---|---|
| Year 1 | +$500.00 | $10,500 | +$511.62 | $10,511 |
| Year 2 | +$500.00 | $11,000 | +$537.78 | $11,049 |
| Year 3 | +$500.00 | $11,500 | +$565.30 | $11,614 |
auto_awesome AI Tip: Starting early is the key to compound growth — even small amounts add up significantly over time
Input your starting amount — the initial deposit for savings or the loan amount for borrowing.
Enter the annual interest rate (APR). For savings, use your bank's stated rate. For loans, use the quoted rate.
Select how long the money will earn or accrue interest. Longer periods show greater compound interest benefits.
Choose simple interest, compound interest, or compare both to see the difference side by side.
For compound interest, choose how often it compounds — daily, monthly, quarterly, or annually.
See total interest earned, final amounts, APY, and the difference between simple and compound interest.
Simple interest is calculated only on the principal amount, making it straightforward to compute. Compound interest is calculated on both the principal and accumulated interest, leading to exponential growth over time. The difference between simple and compound interest becomes more significant over longer time periods.
Simple: I = P × r × t | Compound: A = P(1 + r/n)^(nt)
Compound interest always yields more than simple interest over time
More frequent compounding (daily vs monthly) increases returns slightly
APY (Annual Percentage Yield) accounts for compounding; APR does not
For loans, lower interest rates and shorter terms minimize total interest paid
Use the Rule of 72: divide 72 by interest rate to estimate years to double your money
High-yield savings accounts can offer 4-5% APY — compare rates before depositing
Always compare APY, not APR, when evaluating savings accounts
Our free interest calculator helps you calculate both simple interest and compound interest on savings, investments, and loans. Compare APR vs APY, see how much interest you'll earn on deposits, and understand the true cost of borrowing. Whether you're using a bank interest calculator for fixed deposits or calculating loan interest, get accurate results instantly.
Understanding the difference between simple and compound interest is crucial for financial planning. Simple interest is calculated only on the original principal using the formula I = P × r × t. Compound interest is calculated on principal plus accumulated interest, growing exponentially over time. Our simple interest calculator and compound interest calculator let you compare both side by side.
Use our savings interest calculator to see how much interest you'll earn on savings accounts, CDs, and money market accounts. Enter your deposit amount, the bank's APY, and time period to calculate interest earned. Our bank interest calculator for fixed deposits shows exact returns including the effect of compounding frequency.
Calculate how much interest you'll pay on loans using our loan interest calculator. Whether it's a personal loan, auto loan, or mortgage, understanding total interest paid helps you make better borrowing decisions. See how different rates and terms affect the total cost of your loan.
APR (Annual Percentage Rate) and APY (Annual Percentage Yield) are both interest measurements, but APY accounts for compounding. When comparing savings accounts, always use APY. When comparing loans, look at APR. Our calculator shows both, plus the effective annual rate based on your compounding frequency.
Data sourced from trusted institutions
All formulas verified against official standards.