Calculate simple interest earned or owed based on principal, interest rate, and time. This free simple interest calculator also shows total balance, ending value, and average yearly interest.
Enter your values and click Calculate to estimate simple interest and total amount.
This simple interest calculator uses the standard simple interest formula to calculate how much interest is earned or owed over a set period of time.
Unlike compound interest, simple interest is calculated only on the original principal amount. Interest does not build on previously earned interest.
The standard simple interest formula is:
I = P × R × T
Where:
The total amount is then:
A = P + I
If your loan or deposit is shorter than a year, using months or days can give a more accurate estimate.
Some personal loans, short-term notes, and basic interest arrangements use simple interest instead of compound interest.
Simple interest only uses the original principal. Compound interest grows faster because it includes interest on prior interest.
Inflation can reduce the value of your ending amount over time, especially on longer periods with lower rates.
Simple interest is interest calculated only on the original principal amount, not on accumulated interest.
Simple interest stays based on the starting principal, while compound interest adds interest to the balance and then earns interest on top of that.
Yes. This calculator converts months and days into years so the simple interest formula can be applied correctly.
No. This calculator provides a basic estimate only. Fees, taxes, and penalties are not included.