Will the college fund actually cover four years?

A savings spreadsheet gives you one ending balance and a feeling that it is not quite enough. It is the gap between your return and tuition inflation that decides the answer, and the fund only fails when a weak market lands on top of fast cost growth. This template runs thousands of those futures and turns the answer into a number you can act on this month.

Words on this sheet

Contribution: What is left of the income after the costs that come with it, before the fixed costs are paid.

Personal Finance Intermediate Monte Carlo Pro engine

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After you install, this is the model to open.

Will the College Fund Cover Four Years?

In your spreadsheet, click the Sortia icon in the strip of icons down the right-hand edge. No strip? Click the arrow at the bottom-right to open it. You can also use Extensions, then Sortia, then Open Sortia.
Click Start from a template and put that name in the search box.
Pick the card with that name and click Load this template. It arrives on a new tab with real numbers already in it.

This one runs on a Pro engine, and every free install includes five full-quality runs on your own numbers, shared across all five Pro engines rather than five for each. After that, Pro is $199/year.

The answer

At the most likely rates the plan just works: $222,050 in the fund when she starts, a $253,535 bill, and $3,941 left at the end. The simulation is less comfortable:

Covers all four years: 43% of futures
Median run: -$14,256 short after the last payment
P5 (bad case): -$128,683 short
Four-year bill: $256,297 mean, in future dollars

P5 · -$129Kmedian · -$14KP95 · +$122K

The plan that looks fine on the most likely numbers covers all four years in only about 43% of futures. The median run finishes about $14,256 short and the worst 5% about $128,683 short, on a bill that averages $256,297 in future dollars. That last figure is usually the one that lands hardest. The sheet then does the thing a distribution alone cannot: it converts the shortfall into the extra monthly contribution that would have closed it, which is $0 when the fund holds, about $48 a month at the median run, and about $587 a month in the worst 5%. Costs here are all in, tuition plus housing plus fees, and exclude aid and scholarships.

The model

Eighteen years, one row each: fourteen years of saving, then four years of withdrawals. The balance grows at the investment return and takes that year's contribution, and from the enrollment year it pays that year's inflated cost. Each trial draws one return and one inflation rate and holds both across the horizon.

Balance today	$42,000
Monthly contribution	$450, growing 2% a year
Years until she starts	14
All-in cost today	$32,000 a year for four years
Investment return	0% - 6% - 10% a year (uncertain)
Cost inflation	2% - 4.5% - 7% a year (uncertain)
Money left after the last payment	simulated
Extra per month that closes a shortfall	calculated

Once it is in your sheet

The model arrives with real numbers in it and runs as it stands, so you can press the button first and understand it second.
Change the numbers to yours. The sheet marks which cells are inputs and which hold formulas, and most labels carry a note explaining the row.
Press the run button at the bottom of the panel. It is labeled for the tool you are in, and the result lands on its own tab, with a written reading of it beside the figures.

Never used Google Sheets? Start here goes the whole way, in seven steps, and assumes nothing.

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