Started earlier
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Portfolio at retirement
- Total contributed
- $–
- Investment growth
- $–
- Time contributing
- –
- Time compounding after contributions stopped
- –
Investing time-value calculator
Cost of Waiting to Invest Calculator
See what an investing head start is worth, and what a later investor would need to do to catch up.
Compare someone who starts investing earlier with someone who starts later. Each investor has a start age and a contribution-end age; both balances then compound until the same retirement age.
In compound growth, time sits in the exponent. Giving money more years to compound can have an outsized effect on the final result.
No opinions. No hidden assumptions. Just arithmetic.
Inputs
Early investor
Then stops contributing and lets the balance compound until retirement.
Later investor
Then stops contributing and lets the balance compound until retirement.
Uncheck to enter a different monthly amount for the later investor.
Shared assumptions
%
Entered as an effective annual return and applied to both investors in the main comparison. Zero and negative values are allowed.
Your comparison
Started later
$–
Portfolio at retirement
- Total contributed
- $–
- Investment growth
- $–
- Time contributing
- –
- Time compounding after contributions stopped
- –
What would the later investor need to catch up?
Required return
–
Required monthly contribution
–
Break-even return
–
What if the early investor kept contributing?
–
Ending portfolio if contributions continue to retirement
- Total contributed
- $–
- Investment growth
- $–
Portfolio over time
Started earlier
Started later
How the calculation works
The user-entered annual return is an effective annual return. It is converted to an equivalent monthly rate:
r_m = (1 + r_a)^(1/12) − 1
Contributions occur at the end of each month. The future value of a constant monthly contribution P over n months is:
FV = P × ((1 + r_m)^n − 1) / r_m If r_m = 0: FV = P × n
Each investor contributes a chosen monthly amount for a defined period, then the existing balance compounds with no further contributions until retirement. The two investors can use different monthly contributions.
Assumptions
- Results are in nominal dollars.
- Inflation is not included.
- Contributions are constant and do not increase with inflation.
- Contributions occur at the end of each month.
- The annual return is entered as an effective annual return and converted to an equivalent monthly rate. It is not simply divided by 12.
- Returns are assumed to compound smoothly for illustration.
- Taxes are not included.
- Investment fees are not included.
- No withdrawals occur.
- Results are mathematical illustrations, not forecasts.
FAQ
Why does starting to invest earlier matter?
Earlier contributions have more years to compound. Growth can itself generate additional growth, so time sits in the exponent of the compounding formula.
Can someone who starts investing later catch up?
Yes. They may need to contribute more, earn a higher return, invest longer, or use some combination of these.
Does starting earlier always produce more money?
No. The result depends on returns, contribution amounts, contribution periods, and time horizons. This calculator reports the actual outcome under the assumptions you enter.
What is the break-even return?
It is the shared effective annual return at which the two strategies produce the same retirement value, given the contribution calendars and monthly amounts entered. The search is bounded at approximately −50% to +300%.
Does this calculator account for inflation?
No. Results are nominal dollars and contributions remain constant.
What return does the calculator assume?
Whatever effective annual return you enter. The default 8% is an illustration, not a forecast.
Disclaimer: All content on The Long Math — including articles, essays, calculators, tools, or any other material — is provided solely for educational and informational purposes and does not constitute financial, tax, legal, or investment advice. Any results or projections are based on simplified models, assumptions, and user-supplied inputs and may not reflect real-world outcomes. You are responsible for evaluating the accuracy and applicability of the information provided and for conducting your own due diligence. Before making financial decisions, consult a qualified professional.