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Investing & Retirement

Compound Interest Calculator

Model how a starting balance and regular contributions could change over time under an editable annual return assumption.

$
$
%

Effective annual return assumption; negative values can be used for downside stress tests.

yr

Future Value

$660,849

Total Contributed

$190,000

Estimated Growth

$470,849

Compounding path

Balance vs. the dollars you contributed

7% annual return assumption · 30 years

Yr 0Yr 2Yr 4Yr 6Yr 8Yr 10Yr 12Yr 14Yr 16Yr 18Yr 20Yr 22Yr 24Yr 26Yr 28Yr 30$0k$200k$400k$600k$800k
  • Your contributions
  • Modeled balance

What this means for you

You contribute $190,000 and the modeled return brings the balance to $660,849 over 30 years.

  • $470,849 of the ending balance comes from modeled investment growth rather than contributions.
  • Starting earlier gives each contribution more time to compound. Contribution size still matters materially, so use the timeline and monthly amount together rather than relying on either one alone.
  • This calculator treats 7% as an effective annual return and converts it to an equivalent monthly rate for the projection. Real investment returns are uneven, can be negative for long periods, and are not guaranteed.
See how this fits into your overall retirement plan

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Go deeper in Excel

Retirement & 401(k) Planner

Contribution limits, employer match, Roth vs Traditional, growth assumptions and retirement-gap analysis. The workbook is being built as a reusable companion to MFA's free web tools.

Planned workbook: 401(k) · IRA · Roth/Traditional · retirement projections.

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How Compound Interest Works

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Educational estimates only. Not financial, tax, investment, legal, payroll, mortgage, or insurance advice. Results may vary based on rates, tax rules, lender terms, state laws, and personal circumstances. Financial values entered into supported calculators may be stored privately with technical data such as IP address for MFA analytics, security, debugging and product improvement. Do not enter account numbers, passwords, Social Security numbers or login credentials. Privacy details.