Compound Interest Calculator — See Your Money Grow

See how your money grows with compound interest. Visualize yearly growth, total interest earned, and inflation-adjusted value.

A compound interest calculator reveals one of the most powerful forces in personal finance — the ability of your money to generate earnings on earnings over time. Using the Rule of 72, you can estimate how quickly your investments double: simply divide 72 by your expected annual return.

The frequency of compounding matters more than most people realize. Daily compounding generates slightly more growth than monthly or annual compounding. Even more impactful is starting early — a freelancer who invests $500 per month starting at age 25 will end up with roughly twice as much by retirement as someone who starts at 35.

How to Use This Calculator

  1. Step 1 — Enter your initial investment amount and set your monthly contribution target.
  2. Step 2 — Choose your expected annual return rate — 7% is a common estimate for diversified stock market investments.
  3. Step 3 — Set your investment timeline in years and choose the compounding frequency.
  4. Step 4 — Review the year-by-year breakdown showing total contributions, interest earned, and final portfolio value.

Frequently Asked Questions

What is the Rule of 72?

Divide 72 by your annual return rate to estimate doubling time. At 7%, it takes ~10.3 years.

Compound vs simple interest?

Simple interest earns on principal only. Compound interest earns on principal AND accumulated interest.

How can freelancers invest with irregular income?

Automate a baseline monthly transfer and add lump-sum contributions in high-income months.

What compounding frequency earns the most?

Daily compounding produces the highest returns, marginally beating monthly or annual.

How much should a freelancer invest monthly?

Aim for 15-20% of gross income, prioritizing tax-advantaged accounts like Solo 401(k) or SEP IRA.

Data source: IRS 2026 tax brackets, Social Security Administration wage base, and state revenue department publications. Last reviewed: 2026-07-05.