Compound growth means your returns earn returns. A $10,000 investment growing 7% per year doesn't grow by $700 every year — it grows by $700 the first year, then $749 the next, then $801, and so on.
Over 30 years, that $10,000 becomes about $76,000 with no further contributions. Add a modest $300 monthly contribution and it becomes more than $440,000.
The single biggest lever is time. Starting 10 years earlier matters more than doubling your contribution rate later.
Key takeaways
- Returns on returns is the engine — give it decades.
- Starting early beats contributing more later.
- Consistency, not timing, drives long-term outcomes.
Apply it with these calculators
Written and reviewed by
Keiron Brown, Psy.D.
Founder & Lead Educator, CalculatingWealth
Keiron Brown, Psy.D., is a clinical psychologist and the founder of Relationale LLC, which publishes CalculatingWealth. His doctorate is in psychology, not finance: he is not a registered investment adviser, accountant, or attorney, and nothing here is financial, investment, tax, or legal advice. His work here focuses on financial education, critical thinking, and decision-making — helping people understand the math behind money so they can plan with clarity and confidence. He writes about wealth building, retirement planning, investing literacy, budgeting, and the behavioral patterns that shape long-term financial outcomes.
Editorial standards: All educational content on CalculatingWealth is reviewed for accuracy, sourced from primary references where applicable (IRS, SSA, Federal Reserve, BLS), and updated when rules or rates change. Content is for educational and informational purposes only and does not constitute financial, investment, tax, or legal advice.
Not advice: Keiron Brown is not a registered investment adviser, broker-dealer, certified public accountant, enrolled agent, attorney, or licensed insurance producer. His work is educational in nature. See our full disclaimer.