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Interest Calculator

Find out how much interest an amount earns or costs over time. Enter the amount, the annual rate and the number of years, choose simple or compound interest, and the calculator shows both results so you can see the difference compounding makes.

Quick examples
$
%
years
Your numbers stay in your browser. Nothing is uploaded.
Interest$2,833.59
Ending balance
$12,833.59
With simple interest
$2,500.00
With compound interest
$2,833.59

Saved setups

Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.

    Your recent calculations

    Results you calculate here are kept on this device so you can come back to them.

      Formula

      Simple interest = amount × rate × years
      Compound interest = amount × (1 + rate ÷ n)^(n × years) − amount, where n is compounding periods per year
      Ending balance = amount + interest

      How to use it

      1. Enter the amount and the yearly interest rate.
      2. Enter how many years the money is held or owed.
      3. Choose simple or compound and, for compound, how often interest is added.

      Worked examples

      $10,000 at 5% compounded monthly for 5 years

      Interest
      $2,833.59
      Ending balance
      $12,833.59
      With simple interest
      $2,500.00
      With compound interest
      $2,833.59

      $8,000 at 7% simple interest for 4 years

      Interest
      $2,240.00
      Ending balance
      $10,240.00
      With simple interest
      $2,240.00
      With compound interest
      $2,486.37

      Which type applies to you

      Bank accounts, CDs and credit cards compound, usually daily or monthly. Installment loans such as car loans charge simple interest on whatever balance is left, so the total is lower than this lump-sum figure because the balance falls as you repay; use the loan calculator for those.

      Questions people ask

      How much interest does $10,000 earn in 5 years at 5%?

      Compounded monthly, $2,833.59. With simple interest it would be $2,500, so compounding adds $333.59.

      How much interest does $10,000 earn in a year at 5%?

      Compounded monthly, $511.62 — an APY of 5.116%. With no compounding it is exactly $500.

      How is interest on a savings account calculated?

      Most banks work out interest daily on your balance and pay it monthly. The advertised APY already includes that compounding, so a 4% APY account pays $40 a year per $1,000 left untouched.

      Related calculators

      Simple Interest CalculatorInterest and total owed using I = P × r × t, for years, months or days.Compound Interest CalculatorGrow a balance with compound interest and optional monthly deposits.APY CalculatorConvert an interest rate and compounding frequency into APY.Savings CalculatorHow much your savings will be worth with regular monthly deposits.Loan CalculatorMonthly payment, total interest and a payoff schedule for any fixed-rate loan.