Investment Calculator
Compound interest is the closest thing we have to magic. Einstein called it the "8th Wonder of the World." Our calculator shows how your small monthly savings turn into a mountain of cash over time.
What this calculator does
- Future Value: How rich you'll be in 30 years.
- Interest Earned: How much "free money" your money made.
- Comparison: Saving vs. Investing.
The Formula
- P: Principal (Start money).
- r: Rate of return (e.g., 0.08).
- t: Time in years.
Unlike math class, here's what that means
- Linear Growth: You save $100 a month under a mattress. In 10 years you have $12,000.
- Compound Growth: You invest $100 a month at 10%. In 10 years you have $20,000. In 40 years you have $632,000. (Even though you only put in $48k).
Example Calculation
Start: $0. Save: $500/month. Rate: 8% (Stock Market avg). Time: 30 Years.
- You Saved: $180,000.
- Interest: $565,000.
- Total: $745,000. Most of your money came from interest, not your job.
Did You Know? 💡
- Rule of 72: Divide 72 by your interest rate to see how fast your money doubles. At 10%, it doubles every 7.2 years.
- Inflation: If you keep cash in a savings account earning 0.01%, you are technically losing money because inflation (3%) eats its value. Investing is defense against inflation.
- Time > Timing: Missing just the 10 best days in the stock market over 20 years cuts your returns in half. Just buy and hold.
Expert Insight
The "Wait Tax": Starting at age 25 vs age 35 is massive.
- Start at 25: Save $100/mo -> Finish with $350k.
- Start at 35: Save $100/mo -> Finish with $140k. Waiting 10 years cost you $210,000. Start today.
Why this matters
Retirement isn't an age; it's a number in your bank account. The sooner you hit that number, the sooner you own your time.
Frequently Asked Questions
Is 10% return realistic? Historically, the S&P 500 has averaged ~10% for the last 100 years. However, it's volatile. Some years are +20%, some are -20%. Over decades, it averages out.
What about Crypto? Crypto is high risk, high reward. Traditional investing (Index Funds) is the slow, boring, reliable path to wealth.
Should I pay off debt first? If your debt is high interest (>6%), pay it off. If it's low (<4%), investing might be better.
Related Calculators
- Retirement Calculator: Plan your exit strategy.
- Inflation Calculator: See what money used to be worth.
Disclaimer: Past performance involves risk. This is math, not financial advice.