Finance

Investment Simple Interest Total Calculator (15 Years)

Calculate simple interest and the total amount to repay. This investment version uses a 15-year planning term as its starting point.

The Interest figure is the extra cost of borrowing over 15 years, and the Total figure is the original amount plus that interest, so the full amount to repay is the Total, not just the amount borrowed.

Formula

Simple interest equals principal times rate times time, divided by 100.

How it works

Interest is charged only on the original principal, not on interest already added.

Worked example

Principal $10,000, annual rate 5%, term 15 years. Using the page formula, simple interest equals $10,000 times 5 times 15, divided by 100, which is $7,500.00. Total to repay is $10,000 plus $7,500.00, which is $17,500.00. That is the calculator's own output for these defaults.

Because simple interest never compounds, the interest grows by the same $500 every year: after 15 years it is 15 times $500, which is $7,500.00. At 15 years the interest is three quarters of the amount borrowed, so the total cost is now close to double the original loan before any fees or taxes.

Who this term suits for an investor: a landlord holding a rental property for the medium term, who wants to see the full interest bill of a 15-year loan next to expected rental income before deciding whether the property still pays after costs.

FAQs

What is simple interest?
Simple interest is interest charged only on the original amount, not on accumulated interest.

Is this investment calculator exact?
No, it is an estimate for planning only, based on the numbers you enter.

Are these figures financial advice?
No, they are estimates for planning only, not financial advice. Check with a qualified adviser for decisions involving large sums.

Is $7,500 of interest over 15 years too much for a rental property loan?
It depends on the rent: $7,500 spread over 15 years is $500 a year, so the property must clear at least that much above its other costs every year to carry the loan.

Does simple interest stay simple for the whole 15 years?
On this page it does, because interest is always charged on the original $10,000, but most real 15-year loans compound or amortise, so their true cost will differ.

Should a 15-year investor use this page or a compound page?
Use this page only if the loan really charges simple interest; for a normal mortgage or business loan that compounds, a compound calculator gives the truer figure.

Estimates only, not financial advice. Figures are approximate and do not include all fees, taxes, or changing rates unless stated.