Independent schools get cheaper per student as they grow, up to about 150 students, when the savings run out. So we took a hand-built panel of roughly 497 PK–8 schools and drew the cost curve for the Jewish day schools next to the curve for ordinary private schools of the same size in the same regions.
Two lines below, on the same pair of axes. Left to right is enrollment, from a small school to a large one. Up and down is cost per student, so lower on the chart is cheaper to run. The slate line is the comparison schools. The rust line is the Jewish day schools. Follow each line from left to right and watch where it changes direction.
An original dataset assembled by hand from public IRS Form 990 filings, historical and archived filings, Internet Archive / Wayback captures, and school financial records and public web sources, reconstructed across multiple years. Because the record follows the same schools year over year, it can watch a budget move as enrollment changes, which is what the year-over-year design in this story rests on.
Every finding on this page rests on the assembled record above.
Why is a small school expensive in the first place?
The reason is easiest to see one classroom at a time.
You have to staff third grade whether it holds eight children or twenty. The teacher, the classroom, and the schedule cost about the same either way, so every additional student spreads that fixed cost across more people and the price per student falls.
The saving runs only so far. Once a classroom fills, the next student needs a second section and a second teacher, and the gains stop. Across independent schools generally, the turn arrives somewhere around 150 to 200 students, the oldest and most replicated finding in the economics of school size. Past that point, cost per student levels off and then begins climbing again.
One set of classrooms and one faculty. The rooms fill quickly, and the savings from growth are used up early.
General studies and Judaic studies run side by side in every grade. Twice as much fixed staffing waits to be spread, so there is far more room to keep spreading it.
If a school runs two curricula, what does the second one cost?
The typical comparison school employs about 21 staff for every 100 students. The typical Jewish day school employs about 24, roughly five more employees in a school of 200. Comparing schools of the same size in the same part of the country, Jewish day schools spend about 17% more per pupil, and that gap is solidly established.
The comparison group is a set of ordinary independent, community, and parochial private schools, matched to the Jewish day schools on the things that actually drive cost: enrollment and size, operating budget, campus and facilities, grade range (PK–8), and region and local cost of living. These are everyday private day schools, not elite, high-endowment flagship prep academies. Matching on the cost drivers is what keeps the comparison like-for-like rather than Jewish schools measured against fancy ones.
Every comparison on this page holds school size and region constant, so the two groups differ in how they are built, not in scale or geography.
Two bars below. Each one is the number of full-time-equivalent employees a school carries for every 100 students, at the median, running rightward from zero, so a longer bar means more adults on the payroll per child. The slate bar is the comparison schools. The rust bar is the Jewish day schools.
Look at where the two bars end, and at how little separates them.
A bigger fixed base costs more to carry. It also leaves far more room to keep diluting as the school grows.
Does that bigger fixed base show up in the shape of the cost curve?
A dual-curriculum school starts out more expensive because it carries a bigger fixed staffing base. That same base is also more forgiving of growth, since there is more of it to dilute and it takes far longer to run out of room. The prediction is about shape: the cost curve should fall more steeply and keep falling at sizes where other schools have already flattened.
The chart below is the pair of axes from the hero drawn large. Enrollment runs across the bottom, from 100 students to 600, on a scale that stretches the small schools out. Cost per student runs up the side, with gridlines labelled $25k, $30k, $35k and $40k, so lower on the chart is cheaper per child. The five buttons build the argument a step at a time. Comparison schools draws the slate curve on its own, with a dot at the point labelled "savings run out". Both sectors lays the rust curve for Jewish day schools over it. At 400 students drops a dashed vertical line at that enrollment and puts a dot where each curve crosses it. Staffing channel and Year to year clear the curves away and replace them with two smaller panels, one of bars and one of a number line. Hovering anywhere on the curve reads out cost per student at that enrollment.
Watch what the slate curve does after the dot.
The savings show up where the theory predicts. Press Staffing channel and the panel becomes two bars measuring what happens to a school's staffing as it grows from 150 students to 400. Jewish day schools shed 15.9% of their staff per 100 students, the long rust bar. Comparison schools shed only 4.2%, the short slate one. Pay per employee shows no difference between the groups, so the saving comes from filling two sets of classrooms rather than from paying anyone less.
Press Year to year and the panel becomes a single horizontal line with a mark at each end. The left mark is −1.0, labelled "budget stays fixed", where a school's spending does not move at all when enrollment changes. The right mark is 0, labelled "budget follows enrollment", where spending rises in exact step with the number of children. The two dots on that line are the two sectors, each school compared with itself twelve months earlier. The rust dot sits at −0.92, almost against the fixed end. The slate dot sits out at −0.53, about halfway. A nearly fixed budget is what heavy fixed staffing looks like, and it means each new student arrives close to pure margin.
At the sizes real day schools actually are, how much does the difference come to?
Under about 150 students, both kinds of school are still filling classrooms, and the case for growth is obvious. Between 150 and 250, comparison schools cross over and growth starts costing them money, while Jewish day schools are only beginning to see their savings arrive. At 400 students and up, the gap turns strategic: a 400-student Jewish day school weighing whether to add a section faces genuinely different math than the independent school down the road, and the standard sector advice, built on schools like that one, points the wrong way.
Five pairs of columns below, one pair for each school size: 100, 150, 250, 400 and 600 students. The horizontal line across the middle is zero, marked "no change". A column standing above that line means 10% more enrollment leaves the school costlier per student. A column hanging below it means the same growth leaves the school cheaper. The slate column in each pair is the comparison schools and the rust column beside it is the Jewish day schools, with the figure printed at the far end of every column.
Follow the two colours left to right and watch them pull apart.
What would a school do differently if this is true?
Day school leaders are usually told, correctly, that they cannot grow their way out of a budget problem. That advice comes from research on schools with one curriculum. The structure of a dual-curriculum school appears to change the arithmetic.
If each additional student lowers cost per pupil rather than raising it, admissions and marketing budgets stop being pure overhead and start carrying a measurable return.
Discounting to fill seats looks like lost revenue on a single-curriculum cost curve. On this one, added enrollment lowers unit cost, which changes how a middle-income program pencils out.
Two 200-student schools that combine cut duplicate overhead, and they also land in the size range where the savings run steepest.
One caution belongs alongside all of this. The shape of the curve is supported by every analysis the paper runs, yet it rests on the couple dozen Jewish day schools that report financial data, and the author is careful to call it a well-supported hypothesis rather than a settled fact. Roughly forty more schools reporting would likely settle it for good.
So: growth stops saving most schools money at about 150 students. Does it stop saving these?
Not anywhere the record can see. The comparison schools reach their cheapest point near 150 students and get more expensive from there. The Jewish day schools are still getting cheaper at 600, and the slope is steeper there, at −0.32, than it was at 400 or at 250.
Here is the strongest version of the objection. The 17% level premium is established at conventional significance, but the shape of the curve is not. It rests on the couple dozen Jewish day schools that report financial data, and the author calls it a well-supported hypothesis rather than a settled fact.
What holds the hypothesis up is that four separate research designs point the same way: the fitted curve, the split at 400 students, the staffing channel, and the year-over-year check of each school against itself. Roughly forty more schools reporting would likely settle the question for good.
The curve rests on the couple dozen Jewish day schools that report financial data. Roughly forty more schools reporting would likely settle the question for good.
The difference in curve shape is supported by point estimates in all four of the paper's research designs, and it is not statistically confirmed under the paper's preferred inference method. The author presents it as a well-supported hypothesis.
The cost curves are drawn from the elasticities the paper reports at five reference enrollments and anchored to its reported median expenditures. They reproduce the shape and crossing behavior described in the paper and are not a reproduction of its original figure.
The 17% level premium is established at conventional significance. The difference in curve shape between the sectors is the part awaiting broader financial reporting.
A visual reading of "Scale Economies and the Cost of the Dual Curriculum: Evidence from a National Sample of PK–8 Independent Schools" (Gavriel Brown, working draft, July 2026). The underlying dataset was assembled by hand from public IRS Form 990 filings, historical and archived filings, Internet Archive / Wayback captures, and school financial records and public web sources, reconstructed across multiple years, covering roughly 497 PK–8 schools. The Jewish day schools are cross-referenced against a peer set of comparable independent, community, and parochial private schools, matched on enrollment, operating budget, campus and facilities, grade range, and region rather than drawn from elite flagship prep academies. This is a well-supported hypothesis about the shape of the cost curve, not a settled fact.
How to read the numbers. "Slope" is the percent change in cost per student for a 1% change in enrollment; a negative slope means growing makes the school cheaper per student. All comparisons hold school size and region constant, so the comparison schools are ordinary private schools of similar size in the same regions. FTE counts full-time-equivalent employees across all categories.
Statistics shown are drawn from the paper's reported results. The cost curves are reconstructed from the elasticities the paper reports at five reference enrollments and anchored to its reported median expenditures; they reproduce the shape and crossing behavior described in the paper but are not a reproduction of its original figure. The level premium is established at conventional significance; the difference in curve shape is supported by point estimates in all four of the paper's research designs but is not statistically confirmed under the paper's preferred inference method, and the author presents it as a hypothesis awaiting broader financial reporting.
The paper behind this story
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A data project on how Jewish life is paid for. The work comes in seasons. This page is part of Season 1 — Jewish Education. It states its own sources, sample sizes and limits.
Ahead: Season 2 — Household Affordability · Season 3 — Federation & Charitable Giving
Working prototype. Every figure comes from the underlying research. Where a chart simplifies a published result, the page says so. Nothing here audits an individual school.