Simple interest calculator
Work out simple interest on any amount for years, months or days, and see how it compares with compound interest at the same rate. Free, no sign-up, nothing leaves your browser.
Days are counted on a 365-day year. The compound figure adds interest once a year at the same rate, for comparison.
How simple interest works
Simple interest is paid only on the amount you started with. The formula is amount times yearly rate times time in years: £1,000 at 5% for 3 years earns £150. The interest doesn't earn interest of its own, so it grows by the same amount every year.
Simple versus compound
With compound interest, each year's interest is added to the balance and earns interest too, so the total pulls ahead of simple interest the longer the money is left. Over a few months the gap is small; over decades it is large. Short-term loans, some bonds and late-payment interest often use simple interest, while most savings accounts compound.
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