Simple Interest Calculator
Straightforward interest math for loans and savings.
Simple Interest Calculator
Interest = Principal x Rate x Time
Calculated instantly
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What This Calculator Does
The Simple Interest Calculator finds interest on the original principal only, with no compounding. It is the right tool for short-term loans, late fees, savings bonds, and any agreement stated as flat interest.
How It Works
Simple interest follows the formula I = P x r x t: principal times the annual rate times the number of years. The tool also returns the total balance, which is the principal plus interest.
Example
Deposit R10,000 at a flat 5% annual rate for 3 years. Interest is 10,000 x 0.05 x 3 = R1,500, giving a final balance of R11,500.
Formula
I = P × r × tP = principal, r = annual rate, t = time in years.
Balance = P + IReading the Results
Interest
The flat interest earned or owed on the original principal only, with no capitalization.
Total Balance
The principal plus the simple interest, the final figure for a loan or deposit at maturity.
Frequently Asked Questions
What is the difference between simple and compound interest?
Simple interest is calculated only on the original principal. Compound interest also earns on previously accumulated interest, growing faster over time.
When is simple interest used?
Short-term loans, certain bonds, and flat-rate agreements. Mortgages and standard savings accounts typically compound.
How do I find the rate or time instead?
Rearrange the formula. Rate = Interest / (Principal x Time) and Time = Interest / (Principal x Rate).