What opportunity cost means
In economics, the opportunity cost of a decision is the value of the next best alternative you give up by making it. Applied to a public budget, it is a way of expressing a large and abstract number — billions of dollars — in units people can picture: a school, a hospital bed, a teacher's salary for a year. This tool does exactly one arithmetic operation, dividing the amount you enter by a documented average unit cost, and shows you the formula and the source behind every figure.
Why the cost estimates differ so much
Reported costs for the 2026 US–Iran conflict range from roughly US$29 billion to well over US$130 billion, and the reason is that they measure different things. The Pentagon's acting comptroller told the House Armed Services Committee the figure stood at about US$29 billion, counting direct military operations. CSIS puts the cost to the Department of Defense at around US$40 billion in a preliminary analysis. Moody's Analytics arrives at at least US$132 billion once wider economic effects on taxpayers and consumers are included. None of these is necessarily wrong — they simply draw the boundary in different places, which is why the amount in the tool is editable.
An important limitation of this comparison
Comparisons like "this could have paid for X schools" are a common rhetorical device in budget debates, and they are useful for grasping scale — but they are a simplification, and it is worth being explicit about why. Public budgets are not perfectly fungible: money appropriated for defence is not automatically available for education or housing, those programmes have their own legal, political and capacity constraints, and defence spending is defended on grounds (deterrence, security, alliance commitments) that are not measured in schools or hospitals. The arithmetic here tells you what a sum is equivalent to in other goods; it does not by itself establish that the alternative was available, feasible or preferable. That is a judgement for the reader, not for a calculator.
Where the unit costs come from
Every alternative uses a documented US national average: about US$25 million for a public school of roughly 75,000 ft² (RSMeans/Gordian; TerrapinCG), about US$115 million for a 120-bed hospital (Fixr.com), about US$70,000 for one year of an average public school teacher's salary (NEA), about US$400,000 for a subsidised affordable housing unit, and about US$110,000 for a full four-year scholarship at an in-state public university (College Board). These are broad averages: real costs vary substantially by region, year and specification, so treat the results as orders of magnitude rather than precise counts.
Informational reference: unit costs are broad national averages; the comparison conveys scale, not a policy judgement.
Frequently asked questions
Why is the default amount US$40 billion?
It reflects CSIS's preliminary estimate of the cost to the Department of Defense. Other credible figures range from about US$29 billion (Pentagon comptroller, direct operations) to at least US$132 billion (Moody's Analytics, including wider economic effects). The field is editable so you can use whichever source you prefer.
Does this mean the money should have been spent on schools?
No. The tool performs an arithmetic equivalence, not a policy recommendation. Public budgets are not freely interchangeable, and defence spending is justified on grounds this calculation does not measure. It is intended to convey scale, and the conclusion is left entirely to the reader.
Can I use it for any spending figure?
Yes. The amount is editable, so you can enter any public spending number — a budget line, a subsidy, an infrastructure programme — and translate it into the same alternatives.