Quick Start Guide: Compound Growth Calculator.
This calculator shows exactly how much your regular monthly investments will grow by retirement. No complex math required—just adjust the sliders and watch your future wealth update in real-time.
Step 1: Enter Your Four Numbers
The calculator needs just four inputs:
Current Age: Use the slider to set your age (18-65). This automatically calculates how many years you have until retirement at 65.
Monthly Investment: Slide to set what you'll invest each month ($50-$1,000). Start with what you can realistically afford today—you can always come back to test higher amounts.
Expected Annual Return: Choose your return rate (0-12%). Use 6-7% for conservative planning, 8-9% for moderate, or 10-12% for aggressive projections. The S&P 500 historical average is 10%, but most advisors recommend planning with 7-8%.
Current Savings: Enter what you've already saved for retirement. Include all retirement accounts (401k, IRA, investment accounts). Leave at $0 if starting from scratch.
Step 2: Read Your Results
The moment you adjust any slider, three key numbers update instantly:
- Total at Retirement: Your final balance at age 65
- Total Contributions: Actual money you'll invest from your pocket
- Investment Returns: Free money earned from compound growth
Watch the percentage below Investment Returns—this shows how much of your retirement comes from growth versus contributions. It's often 60-70% returns if you have 15+ years to invest.
Step 3: Understand the Visual Charts
Growth Over Time Chart (Top)
The mountain-shaped graph shows your wealth accumulation year by year. The blue section represents your contributions, while the green section shows investment returns. Notice how the green area explodes in later years—that's compound interest working harder as your balance grows.
Contributions vs. Total Value (Bottom Left)
Two bars compare what you put in (blue) versus what you end up with (green). The gap between them is pure profit from compound growth. This visualization makes it clear why starting now matters.
Cost of Waiting (Bottom Right)
This chart is your motivation to start immediately. It shows your final balance if you start today versus starting in 1, 2, or 5 years. Every year of delay can cost tens of thousands in lost compound growth.
Step 4: Test These Three Scenarios
Your Baseline: Enter your actual age and what you can save today with 7% returns. Screenshot this—it's your starting point.
The Stretch: Increase your monthly contribution by just $100-200. See how this small sacrifice creates massive differences by retirement.
The Maximum: If over 50, test $2,500 monthly (401k catch-up limit). Even if unrealistic now, it shows what's possible with aggressive saving.
Pro Tips for Best Results
- Start Conservative: Use 6-7% returns for planning, then be pleasantly surprised if markets perform better
- Include Everything: Add up 401k contributions, IRA deposits, and taxable account investments for your true monthly number
- Revisit Quarterly: Bookmark the calculator and return every three months to adjust for raises or paid-off debts
- Test Together: If married, run calculations for both spouses' contributions combined
The calculator saves your inputs while the page is open, making it easy to test multiple scenarios quickly. No signup, no email, completely free—use it as often as needed to stay motivated and track your retirement planning progress.