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Ballistic Science & Materials

How Do Bulletproof Helmets Work?

Explore how bulletproof helmets work and their role in full-body protection.

ArmorList Editorial·November 14, 2024·7 min read

Bulletproof helmets, more precisely called ballistic helmets, are worn by military personnel, law enforcement officers and some civilians. They are built to resist named ballistic threats, fragments and blunt impacts, to the extent their test report shows. NIJ's own Body Armor User Guide says no body armor is bulletproof; in our view the same caution applies to helmets.

Understanding how a helmet is built and tested explains what its rating does and does not promise.

This article covers the history, materials, testing, benefits and limits of ballistic helmets, and what to check when choosing one.

History and Evolution of Bulletproof Helmets

Head protection is centuries old, but the modern combat helmet dates from World War I. According to the Smithsonian, when the United States entered the war in 1917 it used a variation of the British Brodie helmet, designated the M1917: a metal dish of about 1.3 pounds that could protect against shrapnel but left the face and the sides of the skull exposed.

Non-metallic materials came later, among them Kevlar, a para-aramid fiber that Stephanie Kwolek invented at DuPont in 1965; the brand now belongs to Arclin. According to the U.S. Army, the Personnel Armor System for Ground Troops (PASGT) helmet, first fielded in 1981, the Advanced Combat Helmet (ACH), first fielded in 2003, and the Lightweight ACH, which first appeared in 2013, all use para-aramid fibers, and each weighed less than its predecessor.

The Army describes newer helmets made from ultra-high-molecular-weight polyethylene (UHMWPE): the ACH Generation II weighs 22 percent less than the ACH and is designed to protect against fragmentation and rounds up to 9 mm.

GAO reports that the ACH was modeled after the Modular Integrated Communications Helmet (MICH), then in use by Special Operations Command. Many current helmets are sold with mounts for communications headsets and night vision equipment; what those mounts do to a helmet's rating is a question for its test report.

To understand this evolution more deeply, you might be interested in the History of Bulletproof Vests, which parallels the development of ballistic helmets.

Materials and Technology Behind Bulletproof Helmets

Modern ballistic helmets are made mainly from aramid fibers such as Kevlar and from UHMWPE. The Army says the ACH family uses para-aramid fibers and the ACH Generation II uses UHMWPE. Spectra is a brand of ultra-high-molecular-weight polyethylene fiber made by Solstice Advanced Materials, which lists it for defense and body armor. What a given helmet stops depends on its model and its test report, not on the fiber.

A helmet has two jobs, and they are tested separately: the shell resists penetration, and the pads and suspension inside reduce blunt impact. GAO describes the ACH's seven pads as mostly "slow-memory" impact foam designed to act like a shock absorber, with comfort foam where they touch the head.

Makers also sell modular components such as visors, communications systems and camera mounts, and suspension and padding systems for comfort over long wear.

Those interested in the broader scope of armor materials may find The Science Behind Bulletproof Materials informative.

How Bulletproof Helmets Are Tested for Safety

A helmet is tested to a named standard or purchase specification, and each one sets its own threats and limits.

  • NIJ 0106.01. NIJ published its ballistic helmet standard in December 1981. It classifies helmets into three types by level of performance and sets requirements for ballistic penetration and ballistic impact attenuation. NIJ's table of active standards lists it as active, with a revision underway. NIJ anticipates that future revisions of its standards for ballistic-resistant helmets and shields will reference NIJ 0123.00, the specification behind the 0101.07 body armor levels.
  • ASTM E3368. ASTM's specification for ballistic-resistant helmets worn by U.S. public safety officers covers handgun and rifle ammunition. It addresses resistance to penetration of the shell, fasteners and weak points, a shell ballistic limit (V50), and non-ballistic tests including impact attenuation, shell compression and retention system strength. Current edition: ASTM E3368/E3368M-25 (checked 1 October 2026).
  • Military purchase specifications. For the Army's ACH, the National Research Council describes testing for resistance to penetration and for backface deformation, measured in clay, across helmet sizes, shot locations and conditioning environments (ambient, hot, cold and seawater). The National Research Council notes that the ACH purchase description sets an acceleration limit of 150 g for a drop at 10 feet per second.
NIJ does not list helmets today. According to OJP, NIJ's Compliance Testing Program does not currently evaluate helmets or shields for compliance to NIJ standards (read 29 September 2026). A helmet marked with an NIJ standard is the maker's claim of testing, not a Compliant Products List entry. BJA's BVP FAQ says ballistic helmets are not eligible for reimbursement under the Bulletproof Vest Partnership.

The CPL answers one question, whether a body armor model met NIJ's program, and helmets are outside it. A helmet is judged on the standard it names and the lab report behind it. For NIJ's body armor standards, see Understanding NIJ Body Armor Standards.

Benefits of Wearing a Bulletproof Helmet

A ballistic helmet protects the head against the threats named in its rating. In our view, that is its whole benefit, and the reason to read the rating before relying on it.

Helmets are also tested against blunt impact. ASTM E3368 includes non-ballistic impact attenuation, and a DTIC study assessed combat helmets against realistic blunt threats such as falls, parachute drops and motor vehicle crashes.

This matters for law enforcement officers and military personnel whose duties include those risks. To understand more about protective gear in policing, you can explore The Role of Body Armor in Law Enforcement.

Modern helmets also offer adjustable straps, padding and, on some models, ventilation, which affect how a helmet fits and how long it can comfortably be worn.

Limitations and Considerations

A ballistic helmet is not invincible. It resists the rounds named in its rating and no others: NIJ 0106.01 classifies helmets into three types, ASTM E3368 classifies them by resistance-to-penetration levels, and a round above the rating, including an armor-piercing round, is outside what the test shows.

Another consideration is weight. In our view, weight and balance matter over long wear, and they are worth comparing across models with the same rating.

Not all helmets are the same. The protection a helmet offers depends on its design and materials as tested, so choose a helmet whose rating matches your documented threats, and read the standard it was tested to.

For how body armor levels handle different threats, Breaking Down Hard Body Armor Levels covers torso armor; helmet ratings are separate.

How to Choose the Right Bulletproof Helmet

Our advice, stated as ours:

  1. Assess the threats you may face, and choose a helmet whose named standard and level cover them.
  2. Ask which standard and edition it was tested to (for example NIJ 0106.01 or ASTM E3368-25), and for the test report, including impact attenuation or backface deformation, not only penetration.
  3. Check fit against the maker's sizing guide; many makers offer several sizes and adjustable padding or suspension.
  4. If you need night vision or communications mounts, ask how they were included in the testing.

Accessories add weight and complexity, so weigh them against your needs. To complement this, you might want to read The Right Way to Fit Body Armor.

Real-Life Applications

Military personnel wear ballistic helmets in combat, where the threats include gunfire, explosions and fragments; the Army describes its ACH Generation II as designed against fragmentation and rounds up to 9 mm.

Law enforcement tactical teams wear helmets in high-risk operations such as dynamic entries.

Journalists in conflict zones wear them too: the Committee to Protect Journalists calls helmets a requirement in war zones and notes that even a top-rated helmet mainly protects against shrapnel.

Conclusion

Ballistic helmets are part of the protective equipment of people who face ballistic and blunt threats at work. Knowing how they are built and tested helps you read what a helmet's rating promises.

A helmet's protection is what its standard, level and test report say, and no more. Choose against your documented threats, ask for the report, and remember that NIJ does not currently list helmets.

On ArmorList, a product's record shows the standards it was tested to, which can include NIJ 0106.01, MIL-STD-662F or VPAM.

Sources

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