Investing $500 a Month Could Turn $120,000 Into $343,650 — If You Let Compounding Work

Putting $500 a month into an S&P 500 index fund will result in a $120,000 personal investment over 20 years. At a 7% average annual return, that grows to $245,972. At 8%, it becomes $274,571. At 9%, $306,960. And at the historical average of 10%, the portfolio reaches $343,650. The gap between what you put in and what you end up with isn't luck or skill. It's compounding, working silently across decades. You don't need to pick winners, watch markets, or time exits. You just need to contribute consistently and stay out of your own way. The math doesn't require optimism. It only requires time.