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Simple Interest Calculator

Calculate simple interest and the total (principal plus interest) from a principal, annual rate, and term. Set the term in years plus extra days, and see the interest earned per year.

Input

$
%

Term (set in years plus days)

yr
days

Days are converted to years assuming 1 year = 365 days.

Result

Total (3% per year, 5 years, simple interest)

$1,150,000.00

Principal

$1,000,000.00

Interest (total)

$150,000.00

Interest per year

$30,000.00

How it works

  • Interest is calculated as "principal x annual rate x years". The entered rate (%) is divided by 100 to get the decimal rate used in the formula.
  • The total is found as "principal + interest". With simple interest, interest is not added back to the principal, so the principal stays constant for the whole term.
  • Interest per year is "principal x annual rate". With simple interest the same amount accrues every year, so the longer the term, the more the total interest grows in proportion to this amount.
  • The term can be set in years plus extra days; days are converted to years assuming 1 year = 365 days (years = years + days / 365) before calculating.
  • Unlike compound interest, simple interest does not earn interest on previously accrued interest. Under the same conditions, the gap from compound interest widens as the term gets longer.
  • Displayed amounts are approximate and rounded. Actual deposits and loans may differ due to rounding rules, crediting units, and taxes (such as tax on interest income). For investment or contract decisions, check the official figures from your financial institution.