The Waiting Tax Calculator

What waiting to invest actually costs

The cost of waiting is not the money you did not invest. It is the growth that money never had time to produce. Compounding rewards time more than it rewards amounts, so the earliest years of investing quietly do the heaviest lifting. Skip them, and no later contribution fully buys them back.

That gap has a number, and most people never run it. A few years of delay can cost more than every dollar you plan to contribute afterward. This calculator puts that number in front of you, so the decision to start is based on the real price of waiting rather than a vague sense that later is fine.

How the calculator works

Set your current age, the age you started or plan to start, your monthly investment, and an expected annual return. The calculator then compares two paths to age 65: one where you started at 18, and one where you start at your chosen age. Both invest the same amount every month at the same return, compounded monthly.

The difference between the two outcomes is the waiting tax: the dollar cost of the years between 18 and your start age. Everything runs in your browser. Nothing you enter is stored or sent anywhere.

Common questions

Is it too late to start investing?

No. The calculator shows that earlier is better, but the second-best start date is always today. Every year you invest still compounds until you stop, so a later start shrinks the outcome rather than erasing it. The waiting tax only keeps growing if you keep waiting.

What return rate should I assume?

Broad stock market index funds have historically averaged around 7 to 10 percent per year over long periods, before inflation. Many people model with 7 or 8 percent to stay conservative. No return is guaranteed, so try a few rates and look at the range rather than a single number.

Is my data stored anywhere?

No. Everything runs in your browser. Nothing you enter is saved, sent, or tracked, and closing the page clears it.