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TCalculator.

Interest Rate Savings Calculator

This free interest rate savings calculator gives you an answer in a couple of seconds, and shows the full working underneath so you can check it rather than take it on trust. Change any value and the result updates immediately. Nothing is stored, nothing is sent anywhere, and there is no sign-up.

Enter your values

Balance after 20 years

$300,850.72

Total contributed
$130,000.00
Interest earned
$170,850.72
Growth on starting amount
$40,387.39
Growth on contributions
$260,463.33

How this is calculated

  1. 1

    Grow the starting amount

    FV = P × (1 + i)ⁿ

    FV = $10,000.00 × (1 + 0.005833)^240

    = $40,387.39

  2. 2

    Grow the regular contributions

    FV = C × ((1 + i)ⁿ − 1) ÷ i

    FV = $500.00 × ((1 + 0.005833)^240 − 1) ÷ 0.005833

    = $260,463.33

  3. 3

    Add both together

    total = FV(principal) + FV(contributions)

    total = $40,387.39 + $260,463.33

    = $300,850.72

  • Returns are assumed constant. Real markets vary, and this ignores tax, fees and inflation.

How to use this interest rate savings calculator

  1. Fill in your values. Every field starts with a sensible default, so you can change one number at a time and watch what it does to the result.
  2. Read the result. The headline figure sits in the pink box, with supporting numbers listed below it.
  3. Check the working. The breakdown shows each formula and the same formula with your numbers substituted in, so you can follow the method or reproduce it by hand.