Compounding Visualizer
See what consistent investing actually becomes over time. Adjust any input and watch every number update instantly.
How to read this
Total contributed is the raw sum of every dollar you put in — your monthly contribution multiplied by the number of months between now and retirement. It's the money you chose to invest, with no market growth assumed.
Interest earned is everything above and beyond what you contributed: returns on your contributions, plus returns on those returns. This is the part most people underestimate.
The gap between the two lines doesn't grow linearly — it accelerates. Early on, almost all your balance is money you contributed. After a couple of decades, the returns on your earlier returns start to outpace your contributions themselves. That widening gap is compounding doing its work, and it's the single best argument for starting sooner with a smaller amount rather than later with a bigger one.
About the default values
Starting balance is set to $0 by default. This is the most universally applicable starting point — it assumes you are beginning from scratch. If you already have savings invested, entering your current balance will give you a more accurate picture of your trajectory.
Monthly contribution is set to $500 by default. At a median individual income of around $56,000 for someone in their mid-twenties, $500 per month represents roughly 10% of gross income — above the national average but achievable for someone being intentional about saving early. The national personal savings rate has historically hovered between 4% and 8%. We set the default higher because the math rewards it significantly.
Annual contribution increase is set to 3.0% by default. US wages have historically grown at approximately 3% to 4% annually over the long term, roughly in line with inflation. This default models the realistic scenario where your contributions grow modestly as your income grows — rather than staying flat in nominal terms while shrinking in real purchasing power terms. Set this to 0% if you prefer to model flat contributions.
Expected annual return is set to 7.0% by default because the tool defaults to After inflation mode. The S&P 500 has historically returned an average of approximately 7% annually after adjusting for inflation since 1926 — nearly a century of data across bull markets, recessions, crashes, and recoveries. This is not a guarantee of future performance, but it is the most historically defensible long-term assumption available. In Before inflation mode the default shifts to 10%, which reflects the same historical data before inflation is accounted for.
Current age is set to 26 by default. This is the age at which most people have settled into their first real career role and are facing meaningful financial decisions for the first time — retirement accounts, savings rates, and the question of what to do with a real salary. It also happens to be the age at which Ethan and Cody begin their story in The Two Paths Saga. The decisions made at 26 show up most dramatically in the compounding math.
Target retirement age is set to 65 by default. While the full Social Security retirement age for most Americans born after 1960 is technically 67, age 65 remains the most commonly cited and widely understood retirement target. It represents 39 years of compounding from the default starting age of 26 — long enough for the compounding effect to become genuinely dramatic.
Returns displayed defaults to After inflation. We made this choice deliberately. Most retirement calculators default to nominal returns, which means the impressive-looking final number includes the effects of inflation — money that will exist in the future but will buy less than it does today. Defaulting to After inflation means the final balance shown is expressed in today's purchasing power. It is a more honest number. Switch to Before inflation if you want to see the raw nominal figure, but we recommend keeping it on After inflation for realistic planning.