Methodology

The headline estimate

The bold figure is the Congressional Budget Office’s estimate of what the war has cost the Department of Defense: $38.1 billion through August 1, 2026. CBO, Congress’s nonpartisan budget office, published it on September 15 in a letter to the House Budget Committee. We do not compute this number ourselves. We cite it, link the source, and update the label when a newer estimate appears.

CBO breaks the total into categories: $21.7 billion to replace expended munitions, $10.4 billion in extra flying hours, $2.7 billion in higher fuel costs, $1.9 billion to replace equipment lost in battle, and $1.5 billion for other operations. The Department of Defense did not answer CBO’s requests for information, so CBO built the estimate from government databases and public reports.

Other estimates run higher. CSIS put the cost of the campaign through the April 8 ceasefire at roughly $40 billion, with a range of $34–42 billion. Much of that difference is base repair, which CSIS counts at $4.0–9.4 billion and CBO leaves out partly because the Pentagon has not given it the data to estimate it. We lead with CBO because it is the most recent independent estimate and covers the longest stretch of the war.

What the estimate does not cover

CBO’s figure leaves out the cost of repairing or rebuilding US bases damaged by Iranian attacks, future veterans’ health care and disability costs, and spending by other parts of the government, such as the Postal Service’s higher fuel bill. It also stops on August 1. The naval blockade of Iran has run since April 13 and is still running. US forces cleared mines from the Strait of Hormuz through August, and on August 30 struck Iranian launchers on Larak Island. CBO estimates that each further month costs the Pentagon about $2 billion when fighting is light and about $3 billion when it runs at July’s level. We do not add those months to the headline ourselves, so read it as the cost through August 1.

The itemized floor

The second figure is the sum of specific reported events we can each point to: a strike, a deployment, an appropriation. Every one has a dollar amount, a date, and a link to the report or government document it came from. When a report gives a range, we use the midpoint. When two sources cover the same spending, we count it once. This is a floor, not the full cost, because plenty of real spending never gets itemized in public reporting.

One entry works differently and is labelled where it appears. When the Pentagon publishes an official running total that exceeds everything we have itemized, we add a single balancing entry for the difference, so the floor sits at the department’s own figure rather than below it. That entry currently carries the gap up to the $29 billion the comptroller reported on May 12. You can read every source behind the floor on the sources page.

Money requested, not yet appropriated

In June the White House asked Congress for $87.6 billion in emergency supplemental funding, $67.1 billion of it for the Pentagon: $21 billion to replace munitions, $17.3 billion for operational costs, $12.1 billion for classified programs, and the rest for drones, cyber, and space systems. CBO found that $42.3 billion of the Pentagon request appears directly tied to the war, about 10 percent more than its own estimate; almost all of the gap is the $17.3 billion for operational costs. None of the request has been appropriated. In July the House adopted a $95 billion budget resolution, 216 to 214, that sets aside more than $70 billion for the war and would let a funding bill pass the Senate on a simple majority. Senate Majority Leader John Thune has said he does not have the votes to take it up. The stopgap bill that keeps the government funded through December 11 left the war money out, and little is expected to move before the November 3 midterms.

We keep the request out of the appropriations line and out of both totals, because a request is not spending. It is here because it is the clearest public signal of what the war is expected to cost next. Status as of September 24, 2026.

Why we do not project a daily rate

The cost was phased, not steady. There was an expensive opening, then a stretch of sustained operations, then a cheaper posture of blockade enforcement and intermittent strikes. Multiplying a single daily rate by the days elapsed would badly misstate the total, so we do not do it. The independent estimate already accounts for the real shape of the spending, which is why we lead with it.

A note on the bigger numbers

You may see far larger figures elsewhere, from $200 billion up to roughly $1 trillion, such as the work of Harvard’s Linda Bilmes. Those measure broad economic impact: knock-on costs, long-term obligations, and effects across the wider economy. That is a different question from direct military outlays, which is what this tracker reports. We keep the two separate on purpose.

One of those wider costs is being measured day by day. The Iran War Energy Cost Tracker, from the Climate Solutions Lab at Brown University, estimates what Americans have paid in extra gasoline and diesel costs since February 28. It compares daily AAA pump prices with a modeled no-war price and multiplies the gap by EIA consumption data. As of late September that came to more than $100 billion, well above the direct military estimate. Households pay it at the pump and in the price of anything shipped by truck. We link to it rather than add it to our totals, because it measures the cost to consumers, not military spending.