Cost of Delay Calculator — The Price of Waiting to Invest

The gap between the two columns

This calculator runs the same contribution schedule twice: once starting today, and once starting after a chosen delay. The headline figure is the difference between the two ending balances. At a monthly investment of 500, an 8% annual return, a 30-year horizon and a 5-year delay, that gap is 269,666.53: the delayed column ends at 475,513.20 against 745,179.72.

The gap is not purely lost growth. A five-year delay also means sixty contributions that were never made, and at 500 a month that is 30,000 of the difference, or 11.1% of it. The other 239,666.53 is compound growth those early contributions would have earned. The split matters because the two parts scale differently: contributions never made rise in direct proportion to the delay, while the growth forgone compounds. At a one-year delay the contributions are 9.5% of the gap; at twenty years they are 18.4%.

How the gap grows with the length of the delay

Contributions made early spend the longest time compounding, so they carry disproportionate weight in the final balance. Removing the first five years of a thirty-year schedule removes the five years with the most runway left, not five average years.

The gap does not grow in proportion to the delay, though, because it cannot exceed the start-now balance. At the sample figures a one-year delay costs 8.4% of that balance, five years costs 36.2%, ten years 60.5% and twenty years 87.7%. Doubling a five-year delay to ten raises the cost by 67%, not by 100%. Each additional year of delay adds less than the one before it, because there is progressively less left to lose.

What moves the number most

Measured at the sample figures, raising each input by 1% of its own value moves the gap by:

• Investment Horizon: 2.42%, the largest on this basis
• Expected Annual Return: 2.22%
• Monthly Investment: 1.00%, exactly proportional
• Delay Period: 0.81%

That basis is proportional rather than practical: the horizon and delay fields both step in whole years, so a 1% nudge is smaller than any move the controls allow. On each input's own smallest step at the sample figures the order changes again: one more year of delay adds 15.65%, half a percentage point of return adds 14.71%, one step of the contribution slider adds 10.00%, and one more year of horizon adds 8.30%. The contribution step differs by currency, but the calculation is linear in it, so a change of any proportion moves the gap by that same proportion.

Monthly Investment is a pure scalar: the whole calculation is linear in it, so doubling the contribution doubles the gap at every combination of the other three. The horizon and the return both compound, which is why a 1% nudge to either moves the result more than a 1% nudge to the amount.

A worked example

A monthly investment of 500, an expected annual return of 8%, a 30-year horizon and a 5-year delay. Starting today, the schedule ends at 745,179.72. Starting five years late, it ends at 475,513.20. The tool returns the difference, 269,666.53.

What the calculation does not include

Returns are nominal. Inflation is not modelled, so a figure thirty years out is in future currency rather than today's purchasing power. Fees, taxes and withdrawals are excluded, as are changes to the contribution amount over time. Both columns pay in the same fixed sum every month for as long as they run.

The delayed column makes fewer contributions in total, which is deliberate: it models starting later on the same schedule rather than catching up. It also assumes a single steady return every month. Real returns arrive unevenly, so the output describes what a constant rate implies rather than what a market will do.

The formula behind this

Both columns use the future value of an ordinary annuity, compounded monthly, with the contribution paid at the end of each month. The delayed column runs for the horizon minus the delay. Subtracting the second from the first gives the figure shown. Where the delay reaches or exceeds the horizon, the delayed column never starts and the gap equals the full start-now balance.