WASHINGTON, — The U.S. Department of Defense has raised the estimated acquisition cost of the F-35 Lightning II program to $536.2 billion, an increase of about $51 billion, or more than 10 percent, from the previous $485.2 billion estimate. The figure covers the aircraft and engines the U.S. government plans to purchase.
The latest Modernized Selected Acquisition Report (MSAR) shows that the increase is spread across development and procurement. Research, development, test and evaluation costs have risen by about $19 billion to $106.6 billion, while procurement costs have increased by nearly $32 billion.
Higher Cost Estimates for All Three Variants
In constant 2012 dollars, the estimated unit recurring flyaway cost—which covers the aircraft and engine—has increased for all three variants:
- F-35A: $78 million, up 7.3 percent from $72.7 million.
- F-35C: $93.4 million, up 6.6 percent from $87.65 million.
- F-35B: $110.3 million, up 10.5 percent from $99.78 million.
These are historical-dollar estimates. The F-35 Joint Program Office has said current-year prices for individual variants in the latest production lots are controlled unclassified information and cannot be released.
Modernization and Production Costs
The increase in development spending is partly linked to a revised estimate for the Power Thermal Management Upgrade, which incorporates updated requirements and assumptions. The program has also revised schedules for Block 4 modernization, the F135 engine core upgrade, and power and thermal-management improvements, adding time and costs. About $900 million of the $19 billion increase in development spending is attributed to refined Block 4 capability estimates.
Block 4 is intended to improve the F-35's weapons, sensors and sensor fusion. The program is prioritizing 55 capabilities, including kill-chain improvements for air-superiority and suppression-of-enemy-air-defenses missions and integration of new weapons.
The nearly $32 billion increase in procurement costs includes the upcoming APG-85 radar, higher production-support costs, the production requirement for the Power Thermal Management Upgrade, contractors' actual costs and negotiated pricing for Lots 18 and 19.
In September 2025, the Pentagon and Lockheed Martin finalized a $24.29 billion contract for 296 F-35s in Lots 18 and 19. Separate engine agreements for those lots were valued at $6.6 billion, giving an implied combined average of about $104.4 million per aircraft and engine across the variants.
Inflation and Procurement Changes
Inflation and higher material prices are also contributing to the higher estimate. The Pentagon is shifting some planned F-35 purchases into later budget years, exposing those future purchases to additional inflation.
The Marine Corps is also changing part of its planned procurement mix by shifting some purchases toward the more expensive F-35C.
Lifetime Cost Estimate Falls
Despite the higher acquisition estimate, the Pentagon's projected total lifecycle cost for the F-35 program has fallen from about $2.06 trillion to approximately $1.93 trillion. The lifecycle estimate covers the broader costs of operating and sustaining the fleet over its projected service life.
The latest assessment therefore shows higher projected costs for developing and purchasing the planned fleet, while the overall projected lifetime cost has moved lower.
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