A common guideline is to save 10-15% of your gross income throughout your career, aiming for a retirement fund of 10-12 times your final annual salary. With $50,000 starting savings and $400 monthly contributions at 7% over 30 years, you'd accumulate approximately $869,000. Your actual target depends on your desired retirement lifestyle, healthcare costs, and other income sources like Social Security.

Starting 10 years earlier can nearly double your retirement fund due to compound interest. Someone who starts at 25 with the same contributions will have significantly more at 65 than someone who starts at 35, even if the late starter contributes more per month. Each year of delay costs you the most powerful years of compounding at the end of your investment timeline.

A 7% return is a widely used estimate that approximates the historical stock market average after accounting for inflation. If your portfolio is bond-heavy or conservative, 4-5% may be more appropriate. For aggressive all-stock portfolios, 8-10% pre-inflation is reasonable. It's wise to run calculations at multiple rates to understand the range of possible outcomes.