Compound Interest Calculator — See Your Money Grow Over Time

Calculate compound interest with regular contributions and see how your money grows with daily, monthly, or annual compounding. Free, instant results and charts.

By Konstantin Iakovlev · Updated September 2026 · Source: SEC

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Future Value

$300,850.72

Total Contributions

$130,000.00

Total Interest Earned

$170,850.72

Summary

Initial Deposit$10,000.00
Monthly Contribution$500.00
Interest Rate (monthly)7.00%
Total Contributions$130,000.00
Total Interest Earned$170,850.72
Future Value$300,850.72

Growth Over Time

Year 5$49,972.70
Year 10$106,639.02
Year 15$186,970.62
Year 20$300,850.72

Use the Compound Interest Calculator — See Your Money Grow Over Time above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

Compound interest is what lets a modest balance grow into a meaningful one, and seeing it laid out year by year makes the effect tangible. Plug in your regular contributions and pick a compounding frequency — daily, monthly, or annually — to project where your savings are headed.

Behind the projection sits the standard formula A = P(1 + r/n)^(nt) + PMT * [((1 + r/n)^(nt) - 1) / (r/n)]. Here A is the future value, P the starting principal, r the annual interest rate, n the number of times interest compounds each year, t the number of years, and PMT each periodic contribution. Combining the growth of your principal with ongoing deposits gives a realistic picture of how the balance accumulates.

A few caveats keep the numbers honest. These figures are projections, and real returns shift with market swings and changing interest rates, so the output is a guide rather than a guarantee. The flip side is easy to overlook: small, steady contributions compound into surprisingly large sums when given enough years to work.

Example: Saving for a Down Payment Over 10 Years

  1. 1 You start with $10,000, add $200 a month and earn 6% a year compounded monthly. Enter $10,000, $200, 6%, 10 years and Monthly.
  2. 2 Starting balance: $10,000 × (1 + 0.06 / 12)^120 = $10,000 × 1.8194 = $18,193.97.
  3. 3 Contributions: $200 × [(1.005^120 − 1) / 0.005] = $32,775.87, grown from $24,000 of deposits.
  4. 4 Future value: $18,193.97 + $32,775.87 = $50,969.84. Of that, $34,000 is money you put in and $16,969.84 is interest, a solid start on a house down payment.

Source: SEC · Last updated: September 2026

Frequently Asked Questions

How does compound interest differ from simple interest?
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus all previously earned interest, causing your money to grow exponentially over time.
How often should interest compound for the best return?
Daily compounding yields the most, but the difference from monthly compounding is minimal. For example, $10,000 at 5% for 10 years yields $16,470 with monthly compounding vs $16,487 with daily compounding.
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 7% return, your investment doubles in roughly 10.3 years. At 10%, it doubles in about 7.2 years.

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