Stock Return Calculator

This stock return calculator models how an initial investment and monthly contributions grow over time through compound returns, dividend reinvestment, and inflation — with a year-by-year growth chart and an inflation-adjusted "real value" to show what your portfolio will actually be worth in today's dollars.

Why Monthly Contributions Matter More Than the Initial Sum

Most wealth is built through consistent contributions, not a one-time lump sum. Adding $500/month to a $10,000 initial investment at 10% over 20 years produces a final balance nearly three times larger than the $10,000 alone — because each contribution compounds from the day it's made. Increasing your monthly contribution by $100 produces far more impact over 20 years than increasing your initial investment by $2,000.

Dividend Reinvestment's Effect on Long-Term Returns

Historically, dividends have contributed roughly 40% of total stock market returns. The toggle in this calculator lets you compare growth with and without reinvestment. With reinvestment, each dividend payment purchases additional shares that themselves generate future dividends — a compounding cycle that materially outperforms simply taking dividends as cash over 10+ year periods.

Nominal vs. Real (Inflation-Adjusted) Value

A $500,000 portfolio in 20 years won't have the same purchasing power as $500,000 today if inflation runs at 3%. The dashed real value line on the chart shows what your projected portfolio would be worth in today's dollars — stripping out inflation's effect. This is the number that matters for retirement planning, not the nominal figure.

Comparing This to Real Estate

The stock return calculator is useful alongside the rental property calculator and rent vs. buy calculator when deciding where to allocate capital. Stocks offer higher liquidity and lower transaction costs; real estate offers leverage and tax advantages. Modeling both quantitatively — with realistic assumptions for each — beats going on instinct.