Compound Interest Calculator

Estimate how your money could grow over time with compound returns, recurring contributions, different compounding schedules, and side-by-side scenario comparisons. Use it for savings goals, investing projections, or to understand how small changes in contribution rate and return assumptions can compound over the long term.

Burrow Tip: Start with realistic assumptions. A small change in annual return or monthly contribution can make a huge difference over long time periods.

Try running a base case, then compare it against a more optimistic and more conservative scenario before making planning decisions.

Growth assumptions

Fees, taxes, and optional adjustments
Use for expense ratios, advisory fees, or blended annual costs.
Optional simplified estimate for annual tax drag on gains.
Checked = annuity due. Unchecked = end of period contributions.
Scenario comparison (optional)

Burrow Tip: Comparison mode is most useful when testing trade-offs, such as “invest more each month” vs “target a higher return” vs “reduce fees.”

Results

Projected future value
$—
Nominal future value before inflation adjustment
Total contributions
$—
Initial amount + all later additions
Investment growth
$—
Future value minus total contributions
Real value (today’s dollars)
$—
Adjusted using the inflation assumption
Effective net annual return
—
After fee drag and optional tax drag
Contribution share of final value
—
How much of the result came from savings vs growth

Portfolio growth over time

Compares future balance against cumulative contributions year by year.

Final value breakdown

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Projection table
The table below shows the first 12 years by default. Use “Show full table” to expand the full projection.
Year Date Starting balance Contributions Growth Ending balance Cumulative contributions Real value
Scenario timeline (Mermaid code)

If your site supports Mermaid elsewhere, you can paste this snippet into a Mermaid block. This tool does not load Mermaid.

How to use these results

Compound interest is powerful precisely because it looks slow at first and then accelerates later. The most important question is not just “What is my projected balance?” but also: “How much of that outcome depends on optimistic assumptions?”

  • Stress-test your return: reduce the annual return by 1%–2% and see how much the final value changes.
  • Check contribution growth: raising contributions over time often matters as much as chasing higher returns.
  • Account for fees: even modest annual fee drag can materially reduce long-term wealth.
  • Use real value too: nominal balances can look large, but inflation-adjusted value gives a clearer sense of future purchasing power.

This tool is best used for planning scenarios, not precise forecasting. The farther out the horizon, the more uncertainty matters.

Disclaimers

Estimates only: This calculator is for educational use and does not constitute investment, tax, legal, or financial advice. It does not predict actual market performance or guarantee future returns.

Assumptions: Growth is modeled using a fixed average annual rate, chosen compounding schedule, optional fee drag, and simplified annual tax drag assumptions. Real-world results vary due to volatility, timing, taxes, withdrawals, and behavioral factors.

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