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Interest Calculator

Calculate simple and compound interest for any savings account, loan, or investment. Compare both methods side by side.

Details
Principal amount
$
Annual interest rate
%
Period
years
Compounding (for compound interest)
Results
Compound Interest Earned
MethodInterestFinal balance

Simple vs Compound Interest

Simple interest is calculated only on the original principal: I = P × r × t. Used for short-term loans, some bonds, and personal loans.
Compound interest earns interest on interest: A = P(1 + r/n)^(nt). Used for savings accounts, term deposits, and most investments.

Australian Reference Rates (2025)

ProductRate (est.)
RBA cash rate~4.10% p.a.
High-interest savings (online)4.5–5.5%
Term deposit (12 months)4.75–5.25%
Personal loan8–18%
Credit card~20.49%