Finance
Simple Interest Calculator
Quickly compute simple interest and total amount for any principal, rate, and period.
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Simple Interest Calculator
$
%
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—Simple Interest
Total Amount
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—Effective Rate
Simple Interest Formula
SI = P × R × T / 100
Where SI = simple interest, P = principal, R = annual interest rate (%), T = time in years.
Total amount = P + SI.
When Is Simple Interest Used?
Simple interest is used for short-term loans, auto loans (in some countries), and savings bonds. It does not compound — interest is only ever calculated on the original principal.
Simple vs. Compound Interest
For the same rate and period, compound interest always yields more than simple interest. The difference grows larger with longer time horizons and higher rates.