How to use this calculator
The basics
Initial Investment: Amount you invest right now.
Monthly Contribution: What you add every month. Consistency matters most.
Time Period: How long you invest. Longer = more powerful compounding.
Advanced
Interest Rate: Expected annual return. Stock market averages 7-10% before inflation.
Compounding Frequency: How often interest is calculated. Monthly is most common.
Understanding compound interest
The compound interest formula is A = P(1 + r/n)^(nt) where P is principal, r is annual rate, n is compounding frequency, and t is time in years.
$10,000 invested at 7% for 30 years grows to ~$76,123 without contributions. Add $500/month and it becomes over $680,000. Start early.
Next steps
Read How to Start Investing with $100 for actionable tips.
Try our Retirement Calculator or 401(k) Calculator to plan ahead.