Enter Financial Parameters

Select your currency, input your principal balance, annual interest rate, and specify the investment timeline using duration or start/end dates.

Run Simple Projection

Click the 'Calculate' button to instantly evaluate fixed returns or interest accumulations over the given time horizon.

Review Final Balance

Analyze your accrued interest totals, monthly/yearly breakdowns, and see the differences made by your optional regular contributions.

What is Simple Interest & How is it Calculated?

Simple interest is a straightforward method of calculating interest only on the original amount you deposited or borrowed — not on any previously earned interest. It is commonly used for personal loans, vehicle loans, education loans, and fixed deposits.

The basic interest calculation is: $$I = P \times r \times t$$ Where I is the interest earned, P is your starting principal, r is the annual rate as a decimal, and t is the number of years.

To find the total amount including your original deposit: $$A = P(1 + rt)$$

Example: You invest ₹5,000 at 5% per year for 4 years. A = 5000 × (1 + 0.05 × 4) = ₹6,000. Total interest earned = ₹1,000, which is ₹250 every single year.

Simple Interest Growth Table ($5,000 at 5%)

Derived Formulas for Financial Projections

If you need to isolate specific data fields, use these standard mathematical variations:

Calculate Principal: $$P = \frac{A}{1 + rt}$$

Calculate Interest Rate: $$R = \frac{1}{t}(\frac{A}{P} - 1) \times 100$$

Calculate Time Period: $$t = \frac{1}{r}(\frac{A}{P} - 1)$$

Simple vs Compound Interest Comparison

Simple interest is calculated only on the principal every time — making it more advantageous for borrowers but less beneficial for savers.

Compound interest, on the other hand, earns interest on already accumulated interest, making it far more powerful for long-term savings growth.

How to Use This Calculator:
Enter your opening balance and annual interest rate, then set how long you want to calculate for. Add any regular contributions if needed, hit Calculate, and instantly get your total interest, final balance, and a complete period-by-period breakdown.