Simple interest and maturity value on a principal.
Maturity value
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Principal
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Interest
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What "simple" really means for your money
Simple interest is the most honest formula in personal finance because it hides nothing. You earn, or pay, a fixed amount each year on the original principal and never a rupee more. The tool multiplies three numbers together: principal, the annual rate as a decimal, and the number of years. That gives the total interest. Add it back to the principal and you have the maturity value. There is no reinvestment, no interest stacking on interest, no quiet acceleration. If you lend a friend PKR 500,000 at a flat 12 percent for five years, the interest is PKR 300,000 whether you read it in year one or year five.
This calculator is built for people pricing short, flat-rate arrangements: a friendly loan with a single agreed return, a promissory note, a vendor who quotes a flat markup, or a back-of-envelope check before you accept a financing offer. It is deliberately not a savings projector, because almost every bank product in Pakistan compounds. Treat the output as a clean baseline, then compare it against anything that reinvests.
Running PKR 500,000 at 12 percent for five years
Take the defaults the calculator loads. Principal is PKR 500,000, the annual rate is 12 percent, and the term is five years. The arithmetic is principal times rate times time, so 500,000 multiplied by 0.12 multiplied by 5. That comes to PKR 300,000 of interest, and the maturity value is PKR 800,000. Because the rate never touches earned interest, each year contributes exactly PKR 60,000, and the line marches up in equal steps.
| Year end | Interest that year | Running balance |
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The result box shows the maturity value and total interest. The chart below shows the principal and accumulated interest breakdown.
Where simple interest quietly costs you
The common mistake is using a simple-interest quote to judge a savings product. Banks and savings schemes pay on a reducing or compounding basis, so a 12 percent compounded deposit beats a 12 percent simple deposit, and the gap widens every year. Run the same PKR 500,000 at 12 percent compounded annually for five years and you finish near PKR 881,000, about PKR 81,000 ahead of the flat result. Over long horizons that difference is not a rounding error, it is the whole point of saving early.
A practical tip: when a lender advertises a low "flat rate" on a car or appliance instalment plan, the true cost is higher than it looks, because you keep paying the flat rate on the full original amount even as you repay the balance. The honest comparison is the reducing-balance or effective rate, not the flat headline. Use this tool to confirm the rupee interest a flat quote implies, then ask the lender for the reducing-balance equivalent before signing.
On tax: interest you earn on a private loan is still income in Pakistan and is, in principle, reportable, while bank profit is usually handled through final-tax withholding at source. This calculator deals only with the gross interest mechanics and applies no tax, so treat any return it shows as pre-tax. Tax rules and the rates that bite on interest income change with each year's Finance Act, so confirm your current position with the Federal Board of Revenue (FBR) before you rely on a net figure.
Does changing the term change the yearly interest?
No. With simple interest the yearly amount is fixed by the principal and the rate alone. Extending from five to seven years at PKR 500,000 and 12 percent simply adds two more PKR 60,000 blocks, taking total interest to PKR 420,000. The term scales the total but never the annual figure, which is exactly what separates simple from compound.
Can I use this for a partial year?
Yes, enter the fraction. Six months is 0.5 years, so PKR 500,000 at 12 percent for 0.5 years yields PKR 30,000. The formula multiplies straight through, which makes it handy for short bridging loans quoted in months rather than full years.