Live scenario calculator
Educational estimates only. Results depend entirely on the inputs and assumptions you choose.
01 — FormulaThe math underneath
Future value of monthly contributions over two different time horizons
The most expensive investing mistake is often invisible: delay. This tool puts a dollar amount on the years that passed before the habit started.
02 — Reality checkWhat this does not include
- Assumes the same monthly amount and same return in both cases.
- Does not account for income changes, taxes, inflation, or fees.
- The result is an estimate of opportunity cost, not a guarantee.
How to use it
Run several scenarios: conservative, middle, and optimistic. The wide gap between those outputs is often more useful than any single answer.
03 — The useful lessonRegret is not the point. The next period is.
This calculator places a dollar value on an earlier start, but the result is not a bill you owe. It is a picture of how many compounding periods were unavailable. The practical question is what contribution, timeline, or goal you can control from today forward.
This isolates time so you can see what the extra years changed.
Stress-test the conclusion instead of letting one optimistic rate dominate it.
Use the result to build a forward plan rather than treating the past as recoverable.
FAQQuestions about starting earlier
Is the cost of waiting a real loss?
It is an estimated opportunity cost, not money removed from an account. The earlier outcome was never guaranteed.
Can a larger contribution make up for lost time?
It can narrow the gap, but the required increase depends on the remaining timeline and the return assumption.
Does the model account for changing income?
No. Both timelines use the same monthly contribution so the effect of time is easier to see.
04 — Time comparison$500 per month at a smooth 7%
| Years invested | Total contributed | Modeled ending value |
|---|---|---|
| 10 | $60,000 | $86,542 |
| 20 | $120,000 | $260,463 |
| 30 | $180,000 | $609,985 |
| 40 | $240,000 | $1,312,407 |
The table is not a promise of 7%. It isolates the value of runway. The practical takeaway is not to chase the past; it is to understand how much the next decade can still matter.
Keep going
This calculator is for education only. It is not financial, investment, tax, legal, or retirement advice.