Questions about Investing
6 direct-answer and decision-guide pages, each backed by primary sources (IRS, SSA, CFPB, FDIC, Federal Reserve) and reviewed by our editorial team.
Direct answers
50–80 word answers up top, then the math, sources, and follow-up FAQs.
How much is $100,000 invested for 30 years?
$100,000 invested for 30 years grows to roughly $432,000 at a conservative 5% real return, $761,000 at the S&P 500's long-run 7% real average, and $1.32 million at a 9% nominal return (about $574,000 in today's dollars after 2.5% inflation). The single biggest lever is staying invested for the full 30 years.
Read the answerHow much should I invest each month?
Most financial planners recommend investing at least 15% of gross income for retirement (Fidelity benchmark), counting employer match. Below 10%, hitting a normal retirement age is mathematically difficult; above 20% gives meaningful flexibility for early retirement or major mid-career goals. Always capture the full 401(k) match before any other investing, it's an instant 25–100% return.
Read the answerWhen should I start investing?
Start investing as soon as you have (1) a starter emergency fund of $1,000–$2,000, (2) no credit-card debt above ~7% APR, and (3) any employer 401(k) match in play. Time in the market matters more than amount: $200/month invested from age 25 to 65 at 7% real return finishes near $525,000; the same $200/month from age 35 finishes near $245,000.
Read the answerWhat return can I expect from the S&P 500?
Since 1928, the S&P 500 has averaged roughly 9.8% nominal return and 6.8% real (inflation-adjusted) return per year, with dividends reinvested. That's the number to use for retirement planning. One-year returns can swing from -37% to +52% and tell you almost nothing about the long run.
Read the answer
Should I…? decision guides
Binary trade-offs with the conditions that flip the answer for your situation.
Should I Pay Off My Mortgage Early or Invest the Money?
If your mortgage rate is below 5% and you have at least 15 years left on the loan, investing the extra money in a diversified stock index fund has historically beaten the guaranteed return of prepayment. Flip the answer if your rate is above 6%, you're within 10 years of retirement, or carrying the mortgage stresses you out, peace of mind has a real return.
Compare optionsLump Sum vs Dollar-Cost Averaging: Which Wins?
Lump-sum investing beats dollar-cost averaging about two-thirds of the time across rolling 10-year windows (Vanguard, 2012/2023), because markets rise more often than they fall. Choose DCA only when (a) the regret of investing right before a 30% drop would push you to sell, or (b) the lump sum is more than 24 months of expenses, where the variance becomes uncomfortable to absorb.
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