Simple Interest Calculator
Enter your principal amount, annual interest rate, and time period to calculate simple interest — interest that accrues only on the original principal, not on previously earned interest.
Save your student profile to track computations, past questions & GPA targets.
Enter principal, rate, and time to see the result.
How It Works
Simple interest is calculated only on the original principal, and stays the same amount every period. The formula is: Interest = P × R × T / 100, where P is the principal (the starting amount), R is the annual interest rate as a percentage, and T is the time in years. The final amount is simply the principal plus the interest: Final Amount = P + Interest.
MyDelsu is an independent student platform and is not affiliated with DELSU administration. This tool is provided for guidance only — always verify results against your official transcript, result slip, or academic regulations.
Frequently Asked Questions
What's the difference between simple and compound interest?+
Simple interest is calculated only on the original principal for every period, so it grows by the same amount each year. Compound interest is calculated on the principal plus any interest already earned, so it grows faster over time. For that calculation, use the Compound Interest Calculator.
Can I use this for a loan I'm repaying, not just savings?+
Yes — the same formula works whether you're calculating interest earned on savings or interest owed on a simple-interest loan; P is just the amount borrowed instead of the amount saved.
Does the rate need to be an annual rate?+
Yes — enter the annual (yearly) interest rate as a percentage, and enter your time period in years (e.g. 6 months = 0.5 years). If you have a monthly rate, multiply it by 12 first to convert it to an annual rate.
Why is my interest amount showing as 0?+
Double-check that your rate isn't 0% and that your principal and time are both greater than 0 — all three values are required to calculate interest.
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