Using data from the Air Force and the Department of the Navy (DoN), the Congressional Budget Office has projected how the U.S. military’s current force of about 3,300 fighter aircraft is likely to change over the next 14 years. CBO’s projection is based on statements by the Department of Defense (DoD) about plans for the types of aircraft the military will acquire, as well as expectations about when current aircraft will be retired. The details of DoD’s long-term plans for the structure of its fighter force are not publicly available. Although CBO drew on the insights of experts at DoD, this projection is CBO’s. The projection offers a look at what the fighter fleet will be like in future years: how old various aircraft will be, the percentage of the fleet that will be stealthy (that is, more difficult for adversaries to detect), and the fleet’s rates of availability and use.1

The analysis focuses on fighter aircraft—those bearing the prefix F- for fighter or A- for attack—operated by the Air Force, Navy, or Marine Corps. (The data CBO used do not clearly differentiate between Navy and Marine Corps aircraft, so CBO grouped them as DoN aircraft.) In this analysis, the fighter fleet includes EA-18Gs, electronic warfare aircraft operated by DoN that are based on F/A-18Fs. CBO excluded older F-16s that DoN obtained from the Air Force and other sources and repurposed as training aircraft or as stand-ins for enemy aircraft in exercises. CBO also excluded fighter aircraft that are in storage. (The Air Force’s REMIS data system includes aircraft in long-term storage, most of which are at Davis-Monthan Air Force Base in Arizona. DoN’s DECKPLATE data system does not include stored aircraft. Excluding stored aircraft listed in REMIS makes the two data sources more comparable.)

CBO’s Approach to Projecting Future Fleets of Fighter Aircraft

CBO projected how DoD’s 2025 fighter fleet would develop and change through 2040. The projection required estimating when new aircraft would begin operating as well as when older aircraft would be retired. (CBO focused on when aircraft enter service, which is generally two or three years after they are procured.) In most cases, CBO projected that old fighter jets would be retired on a one-for-one basis when new aircraft arrived. In some cases, CBO projected a different ratio because newer aircraft would be more capable than the aircraft they would replace.

CBO’s projection does not include the effects of attrition—the loss of aircraft in combat or accidents. Although DoD’s procurement goals typically include enough aircraft to account for attrition, DoD also could replace lost aircraft by purchasing additional aircraft of the same or a different type. In the absence of a major conflict (one larger than the current hostilities with Iran), the effects of attrition are expected to be small.

For indications of DoD’s plans, CBO drew on resources such as Selected Acquisition Reports, budget requests, and other statements of DoD’s intent. CBO’s projection includes two types of fighter aircraft that have not yet been fielded: the Air Force’s F-47 and DoN’s next-generation fighter, which the department refers to as the F/A-XX. Plans for those aircraft are still being finalized, so CBO relied on statements by DoD officials to create its projection for those two fleets.

Decision-makers could choose to pursue policies that are different from those underlying CBO’s projection. For instance, ongoing military conflict could change DoD’s plans for how many and which kinds of manned fighter aircraft it will acquire. However, altering the fundamental characteristics of DoD’s fighter fleets would take many years, so small changes in policy are unlikely to affect the basic findings of CBO’s analysis.

In CBO’s projection, the Air Force’s fighter fleet initially shrinks as A-10s are retired, as two F-15C/Ds are retired for each F-15EX that arrives, and as four earlier-generation F-16C/Ds (most of which entered service before 1989) are retired for every three F-35As that arrive. The Air Force’s fleet starts growing in the early 2030s, after all earlier-generation F-16C/Ds have been retired, as later-generation F-16C/Ds remain in the fleet and more F-35As arrive. (Later-generation F-16C/Ds have stronger structures and better avionics than earlier-generation F-16C/Ds.) The size of DoN’s fighter fleet, by contrast, remains relatively stable through 2040 in CBO’s projection.

That projection is just one possible trajectory for DoD’s force of fighter aircraft. If the department bought more fighters or bought them more quickly than it now plans to do, the average age of various fleets would decrease more rapidly. Alternatively, DoD could expand the fighter force by not retiring older aircraft when new ones arrive or by delaying retirements (akin to how CBO treats F-22 retirements, which, at the suggestion of an Air Force expert, are projected to lag F-47 arrivals by five years). Delaying retirements rather than immediately retiring aircraft when new ones arrive would increase the average age of a fleet.

DoD could use service-life extension programs to delay the retirement of aircraft longer than CBO projects. CBO analyzed the consequences of those programs in a 2021 report.2

In CBO’s projection, the oldest aircraft of a given type are retired first. If that pattern is followed, the average age of a shrinking fleet will not increase by one year for each year that passes. If aircraft are not retired in that way, CBO’s estimates of fleets’ average ages in the future will be too low.

CBO’s Projection for Various Fleets of Fighter Aircraft

Using the data and specifications described above, CBO projected the size, percentage of stealthy aircraft, and average age of the Air Force’s and DoN’s fighter fleets through 2040. CBO also examined how past patterns of aircraft procurement affected the current age distribution of those fleets and how the size and average age of fleets of specific types of aircraft are projected to differ in 2025 and 2040.

CBO presents aircraft inventories as annual averages that are based on the amount of time aircraft (excluding those in storage) are possessed by the military services, as reported in REMIS and DECKPLATE. Those inventories may differ from other measures of aircraft inventories commonly used by the U.S. military, such as primary aircraft authorization (PAA) or total aircraft inventory (TAI).

Projected Fleet Size

Over the past quarter century, the total size of DoD’s fighter fleet has varied from about 3,300 aircraft to almost 4,000. The size of that fleet, currently about 3,300 aircraft, will decline for the next several years and then increase to approximately 3,600 aircraft in 2040, CBO projects. Within that overall fleet, the number of fighter aircraft operated by the Air Force will grow from 2,200 in 2025 to 2,400 in 2040, while the number of fighter aircraft operated by DoN will remain at roughly 1,200.

Projected Share of Stealthy Fighter Aircraft

Stealthy aircraft have designs and materials that make them harder to detect with radar than nonstealthy aircraft. Those attributes enhance their ability to survive in combat. However, stealth characteristics increase the costs of procuring and maintaining aircraft and reduce the number of weapons a fighter aircraft can carry. The Air Force has operated three types of stealthy fighter (the now-retired F-117, the F-22, and the F-35A), and DoN has operated two other types (the F-35B and the F-35C). Both military departments are planning future stealthy fighters (the F-47 for the Air Force and the F/A-XX for DoN).

The share of the military’s fighter fleet that is stealthy has increased steadily for the past quarter century. In 2025, 27 percent of DoD’s fighter aircraft were stealthy: 30 percent of the Air Force’s fighters and 22 percent of DoN’s fighters. By 2040, more than 60 percent of each department’s fighters will be stealthy, CBO projects.

Projected Aircraft Age

The age of military aircraft is important to lawmakers and defense policymakers because older aircraft raise several concerns:

• Unless their technology has been refreshed, older aircraft may lack capabilities that DoD desires. (Some capabilities, such as stealthiness, cannot easily be added to existing aircraft. Postproduction modifications such as applying radar-absorbent coatings may reduce the detectability of a nonstealthy aircraft, but they cannot achieve the same degree of stealthiness as a purpose-built design.)
• As aircraft age, they may require increasingly extensive or difficult maintenance to continue operating, may need to spend more time in depot-level maintenance, and may have lower rates of availability.
• Acquiring spare parts for older aircraft may become difficult, especially if newer versions of the aircraft are no longer being manufactured. Supply issues may be easier to address for aircraft such as F-16C/Ds, many of which have been sold to foreign militaries, thus keeping the production line active, than for F-22s, which have not been sold abroad.

The average age of the Air Force’s fighter fleet has generally increased in recent decades. It peaked at 28.2 years in 2024 and then decreased slightly, to 27.7, in 2025. The Air Force’s fighter fleet has consistently been older, on average, than DoN’s fleet. The average age of a DoN fighter peaked at 16.6 years in 2018 and then declined to 14.7 in 2025. The average age of fighter aircraft in 2040 is projected to be 21.4 years for the Air Force and 16.6 for DoN.

Effects of Past Aircraft Procurement on the Age of the Current Fleet

In 2025, many of the Air Force’s fighter aircraft were in their 30s; few were in their 20s. That age pattern is a direct consequence of the service’s uneven history of aircraft procurement. The Air Force purchased many more fighters each year from 1980 to 1991 than it did in later years.

In the 1980s and 1990s, fighter aircraft generally entered service two years after they were procured. For example, an F-16C/D that was purchased in 1988 probably entered service in 1990. If it was still in service in 2025, it would have been in its 36th year of operation.

Ages are much more evenly distributed in DoN’s fighter fleet. The department’s annual procurement declined less markedly than the Air Force’s after 1991 (after the Cold War ended) and rebounded in less than a decade.

Projected Changes to Fighter Fleets From 2025 to 2040

The mix of types of fighter aircraft in the U.S. military is projected to change between now and 2040. In the Air Force, A-10s, F-15C/Ds, and F-15Es will leave service; the number of F-16C/Ds will decline; and the number of F-35As will more than double. In the Department of the Navy, AV-8s and F/A-18C/Ds will retire, the number of F/A-18E/Fs will decline, and the number of F-35Bs and F-35Cs will increase.

In 2040, the Air Force’s two largest fighter fleets will have very different average ages. The service’s 605 F-16C/Ds will be 48 years old, on average, whereas its nearly 1,200 F-35As will be just 12 years old, on average. DoN’s fighter fleets will all be under 30 years old, on average. Its largest fleet, F-35Cs, will have an average age of 12 years.

CBO’s Projection of Fleet Availability and Use

On the basis of the characteristics of the fighter fleet described above, CBO projected the fleet’s future availability rate (the percentage of aircraft in the fleet that are available to be flown on training or operational missions during a year) and the fleet’s usage rate (the average number of hours aircraft are flown per year). That projection involves various areas of uncertainty, not least of which is how aircraft will perform at ages that have not been seen before.

Uncertainty About Availability and Usage Rates for Older Fighter Aircraft

In CBO’s projection, the average later-generation F-16C/D will be 48 years old in 2040. There is considerable uncertainty about how well those aircraft will operate at that age. In the past, fighter aircraft have generally had lower availability and usage rates as they have aged. To explore that uncertainty, CBO plotted two trends for availability and usage rates for F-16C/Ds by age: one in which rates hold steady through 2040 at the levels seen at age 35 and one in which the average annual pace of decline in those rates seen through age 35 continues through 2040.

Projected Rates of Availability and Use

Overall, CBO projects that the military’s fighter fleet will experience declining availability and usage rates through 2040, even though the fleet will be younger, on average, than it is now. (That projection extends through 2040 the average annual pace of decline in those rates seen through age 35.) The reason for the projected declines is that a greater percentage of fighter aircraft will be fifth-generation stealthy aircraft, which have had lower availability and usage rates than earlier types of nonstealthy fighters.3 (In the projection, sixth-generation F-47s and F/A-XXs have availability and usage rates by age that are similar to those of fifth-generation F-22s and F-35Cs, respectively.) Thus, CBO projects that, on average, an Air Force fighter will be available for use 45 percent of the time in 2040, and a DoN fighter will be available 35 percent of the time.

Various factors could increase those rates. DoD has major efforts underway to improve the reliability of F-35s, including upgrading their engine core and redesigning their thermal management system, which keeps critical systems from overheating. F-35s may also have higher availability rates if their Block 4 upgrade is completed successfully or if their logistics system is expanded.4 F-47s and F/A-XXs may have more reliable designs than current stealthy fighter aircraft, which would increase their availability rates.

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1. 1. In this report, CBO uses the term “stealthy” to refer to fifth-generation or later fighter aircraft. Although fifth-generation fighters are mainly distinguished by their stealth characteristics (such as airframes that are shaped to control radar reflections, coatings that absorb radar signals, and weapons that are carried internally), they also have advanced sensors and integrated avionics to enhance their offensive and defensive capabilities. The F-22 and F-35 are considered fifth-generation fighters. The F-47 and F/A-XX, which are expected to include more advanced capabilities, are considered sixth-generation fighters. CBO also categorized the F-117 fighter of the 1980s as stealthy.

2. 2. Congressional Budget Office, The Effects of Large-Scale Maintenance Actions on the Availability of Air Force Aircraft (September 2021), www.cbo.gov/publication/57258.

3. 3. Congressional Budget Office, Availability, Use, and Operating and Support Costs of F-35 Fighter Aircraft (June 2025), pp. 7–8, www.cbo.gov/publication/61347.

4. 4. In June 2026, the head of the F-35 program office testified that the current F-35 logistics system is supporting more than 1,300 aircraft, despite having a capacity for 700 to 800 aircraft. See the testimony of Lieutenant General Gregory L. Masiello, U.S. Marine Corps, before the Subcommittee on Airland of the Senate Armed Services Committee, To Receive an Update on the F-35 Aircraft Program (June 23, 2026), https://tinyurl.com/yvxcmey9.

About This Document

This report was prepared at the request of the Chairman and Ranking Member of the Subcommittee on Tactical Air and Land Forces of the House Committee on Armed Services. In keeping with the Congressional Budget Office’s mandate to provide objective, impartial analysis, the report makes no recommendations.

Edward G. Keating and Katherine Driebe prepared the report with guidance from David E. Mosher. Nikhil Bhandarkar and Joseph Uren (both formerly of CBO) contributed to the analysis. Ron Gecan, Kyoung Mook Lim, Christopher Martin (formerly of CBO), and R. Derek Trunkey offered comments. David Arthur fact-checked the report.

Jennifer DiMascio of the Congressional Research Service and Daniel M. Norton of the RAND Corporation commented on an earlier draft. The assistance of external reviewers implies no responsibility for the final product; that responsibility rests solely with CBO.

Jeffrey Kling reviewed the report. Christian Howlett edited it, and R. L. Rebach created the graphics and prepared the text for publication. The report is available at www.cbo.gov/publication/62538.

CBO seeks feedback to make its work as useful as possible. Please send comments to communications@cbo.gov.

Phillip L. Swagel

Director

July 2026