Calculate total amount (A = P + I) using the simple interest formula A = P(1 + rt). Enter your principal, annual interest rate, time period, and time unit — and get back the total accrued amount, interest earned, and a year-by-year schedule showing how your balance grows.
Total Amount (A = P + I)
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Total Interest (I)
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Principal (P)
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Effective Annual Rate
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Simple interest is calculated only on the original principal amount — it does not compound. The formula is I = P × r × t, where P is principal, r is the annual rate as a decimal, and t is the time in years. It is commonly used for short-term loans, car loans, and savings bonds.
The formula is A = P(1 + rt), where A is the total accrued amount (principal plus interest), P is the principal, r is the annual interest rate as a decimal (rate% ÷ 100), and t is the time in years. The interest portion alone is I = Prt.
Convert your time period to years by dividing the number of months by 12. For example, 6 months = 6/12 = 0.5 years. Then apply the formula A = P(1 + r × 0.5). This calculator handles the conversion automatically when you select 'Months' as the time unit.
Divide the number of days by the day-count convention — either 365 (exact/actual) or 360 (banker's rule). For example, 90 days on a 365-day basis equals 90/365 ≈ 0.2466 years. Both options are available in the Time Unit dropdown above.
Simple interest is used in short-term personal loans, auto loans, U.S. Treasury bills, certificates of deposit (CDs) with a single payout, and some student loans. It is also used as the basis for calculating APR on many consumer credit products.
With simple interest, you only earn (or pay) interest on the original principal. With compound interest, you earn interest on both the principal and previously accumulated interest. Over long periods, compound interest grows significantly faster — making it more favorable for savings but more costly for loans.
Rearrange the formula: R = (A − P) / (P × t) × 100. Simply subtract the principal from the total amount to get interest earned, then divide by the product of principal and time (in years), and multiply by 100 to express as a percentage.
Yes. The yearly schedule table below the results shows the interest earned each year, cumulative total interest, and running balance for every year of the term, giving you a clear picture of how your investment or loan grows over time.