simple interest
Simple Interest is the plain, no compounding way to calculate interest, based only on the original amount you borrowed or saved, not on interest already earned.
In plain English
"Oga, why is my brother's loan interest not growing like mine?" Tunde asked his cousin at the bank. "Because his own is simple interest," the cashier said. "It only counts the money he first borrowed. Yours is compound, it counts on top of interest too. That is why yours is climbing like okada in traffic."
That short exchange is really the whole story of simple interest. It is the calmest, most predictable member of the interest family. You borrow or save a fixed amount, called the principal, and the interest is worked out on that one figure alone, for as long as the money sits there. It does not ask what happened last month. It does not add interest on top of interest. It just does the same small calculation, year after year, on the original sum.
In Nigeria, some cooperative societies and small thrift schemes still use simple interest for member loans, because it is easy to explain to everybody at the meeting, from the market woman to the civil servant. A UK example would be some fixed term savings bonds and certain personal loans that quote a flat annual rate, so you know from day one exactly what you will pay or earn, with no surprises hiding in the fine print.
For someone in London sending money home to fund a small loan scheme for family in Warri, simple interest is the friendly option to explain over the phone. Nobody needs a calculator app or a finance degree. Everybody can check the sum themselves, and that transparency builds trust, which matters more than people admit when money and family mix.
You borrow ₦200,000 at 10% simple interest per year for 3 years. Interest each year is 10% of ₦200,000, which is ₦20,000. Over 3 years that is ₦60,000 total interest, so you repay ₦260,000. The interest never grows on itself, it stays ₦20,000 every single year.
Questions people ask
Is simple interest better than compound interest?
It depends on which side of the loan you are on. As a borrower, simple interest usually costs you less over time because interest never grows on itself. As a saver, compound interest usually earns you more, because your interest starts earning its own interest.
Where is simple interest commonly used in Nigeria?
You will often meet it in cooperative society loans, some thrift and esusu style schemes, and certain short term personal loans, where lenders want the calculation to be easy for everyone to follow without confusion.
How do I calculate simple interest myself?
Multiply the principal by the interest rate by the number of years. For ₦100,000 at 5% for 2 years, that is ₦100,000 times 0.05 times 2, which gives ₦10,000 in total interest.
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