Body Armor Fundamentals

What is body armor?

Hard body armor plates are generally designed to protect against high-energy projectiles, such as rifle rounds. These plates typically consist of rigid panels that fit inside vests or plate carriers. Soft armor, in contrast, is meant to stop handgun rounds and shrapnel — and is not rated to stop rifle threats. 

Modern hard body armor systems are a result of advanced materials science and engineering, and utilize some of the world’s most extreme materials.

This guide is designed to help you understand the basics of hard body armor — from what threats it’s usually rated for, to how it’s made, to how to assess its cut, and more.

Modern armor science is a complex interdisciplinary subject — which touches on materials science, impact mechanics, ballistics, adhesive chemistry, and much more — but the basics are straightforward.  With those in hand, you’ll be able to make the best possible decisions with respect to purchasing and using body armor. 

Body Armor Levels Explained

There are multiple body armor rating systems, but there are three rating systems that are utilized more frequently than the rest.  And the foremost of these is the NIJ’s 0101.06 standard for body armor.

NIJ 0101.06 (“.06”), Body Armor:

Level I
Protection: .22 LR, .380 ACP
Bullets:
2.6 g (40 gr) .22 Long Rifle Lead Round Nose (LR LRN) at 329 m/s (1080 ft/s ± 30 ft/s)
6.2 g (95 gr) .380 ACP Full Metal Jacketed Round Nose (FMJ RN) at 322 m/s (1055 ft/s ± 30 ft/s)

Level IIA
Protection: 9×19mm, .40 S&W
New Armor:
8 g (124 gr) 9×19mm Parabellum FMJ RN at 373 m/s ± 9.1 m/s (1225 ft/s ± 30 ft/s)
11.7 g (180 gr) .40 S&W FMJ at 352 m/s ± 9.1 m/s (1155 ft/s ± 30 ft/s)
Conditioned Armor:
8 g (124 gr) 9 mm FMJ RN at 355 m/s ± 9.1 m/s (1165 ft/s ± 30 ft/s)
11.7 g (180 gr) .40 S&W FMJ at 325 m/s ± 9.1 m/s (1065 ft/s ± 30 ft/s)

Level II
Protection: 9mm +P, .357 Magnum
New Armor:
8 g (124 gr) 9 mm FMJ RN at 398 m/s ± 9.1 m/s (1305 ft/s ± 30 ft/s)
10.2 g (158 gr) .357 Magnum Jacketed Soft Point at 436 m/s ± 9.1 m/s (1430 ft/s ± 30 ft/s)
Conditioned Armor:
8 g (124 gr) 9 mm FMJ RN at 379 m/s ±9.1 m/s (1245 ft/s ± 30 ft/s)
10.2 g (158 gr) .357 Magnum Jacketed Soft Point at 408 m/s ±9.1 m/s (1340 ft/s ± 30 ft/s)

Level IIIA
Protection: .357 SIG, .44 Magnum
New Armor:
8.1 g (125 gr) .357 SIG FMJ Flat Nose (FN) at 448 m/s ± 9.1 m/s (1470 ft/s ± 30 ft/s)
15.6 g (240 gr) .44 Magnum Semi Jacketed Hollow Point (SJHP) at 436 m/s (1430 ft/s ± 30 ft/s)
Conditioned Armor:
8.1 g (125 gr) .357 SIG FMJ Flat Nose (FN) at 430 m/s ± 9.1 m/s (1410 ft/s ± 30 ft/s)
15.6 g (240 gr) .44 Magnum Semi Jacketed Hollow Point (SJHP) at 408 m/s ± 9.1 m/s (1340 ft/s ± 30 ft/s)

Level III
Protection: Rifles (7.62×51mm NATO)
Bullets: 9.6 g (148 gr) 7.62×51mm NATO M80 ball at 847 m/s ± 9.1 m/s (2780 ft/s ± 30 ft/s)

Level IV
Protection: Armor Piercing Rifle (.30-06 Springfield)
Bullets: 10.8 g (166 gr) .30-06 Springfield M2 armor-piercing (AP) at 878 m/s ± 9.1 m/s (2880 ft/s ± 30 ft/s)

Note: Backface deformation is limited to 44mm, across all threat levels.

Note: Levels I through III are tested against six shots per plate or panel, per threat.  Level IV can be tested at one to six shots per panel, at the manufacturer’s discretion.  Virtually without exception, manufacturers choose to test Level IV plates for certification at one shot per panel.

Levels up to IIIA are generally intended for soft armor panels, though one does rarely encounter metal or UHMWPE armor that’s rated to Level IIIA.  Level III and IV refer to hard armor plates.

There are numerous well-known problems with the 0101.06 specification, but one is of particular importance: “Level III,” which is supposed to describe armor capable of defeating most if not all non-AP rifle threats, misses the mark.  The M80 Ball is a relatively weak armor penetrator, and there are many common rifle ball threats — including the M193 and similar rounds — that can often penetrate “Level III” armor rated for M80 ball.  

This has led to the unofficial “Level III+” designation, which has no official or common meaning.  It means whatever the people who applied the designation want it to mean.  It usually means M80 Ball plus 5.56x45mm M193 and M855.  But not always.  In some cases, it means little more than M80 Ball plus 7.62x39mm mild steel core.  To resolve this problem, the NIJ has recently released an update to their body armor rating system, NIJ 0101.07.  

NIJ 0101.07 (“.07”), Body Armor:

Handgun 1 (HG1)
Bullets:
8 g (124 gr) 9 mm FMJ RN at 398 m/s ± 9.1 m/s (1305 ft/s ± 30 ft/s)
10.2 g (158 gr) .357 Magnum Jacketed Soft Point at 436 m/s ± 9.1 m/s (1430 ft/s ± 30 ft/s)

Handgun 2 (HG2)
Bullets:
8 g (124 gr) 9 mm FMJ RN at 448 m/s ± 9.1 m/s (1470 ft/s ± 30 ft/s)
15.6 g (240 gr) .44 Magnum Semi Jacketed Hollow Point (SJHP) at 436 m/s ± 9.1 m/s (1430 ft/s ± 30 ft/s)

Rifle 1 (RF1 – Ball Rounds)
Bullets:
9.6 g (149 gr) 7.62×51mm NATO steel-jacket M80 ball at 847 m/s ± 9.1 m/s (2780 ft/s ± 30 ft/s)
7.97 g (123 gr) 7.62x39mm MSC Ball Ammunition Type 56 from Factory 31 at 732 m/s ± 9.1 m/s (2400 ft/s ± 30 ft/s)
3.6 g (55 gr) 5.56×45mm M193 BT at 990 m/s ± 9.1 m/s (3250 ft/s ± 30 ft/s)

Rifle 2 (RF2 – Steel Penetrators)
Bullets: 4 g (62 gr) 5.56×45mm M855 BT at 950 m/s ± 9.1 m/s (3115 ft/s ± 30 ft/s)

Rifle 3 (RF3 – Armor Piercing Rifle)
Bullets: 10.8 g (166 gr) .30-06 M2 armor-piercing (AP) at 878 m/s ± 9.1 m/s (2880 ft/s ± 30 ft/s)

Note: Backface deformation is still limited to 44mm, across all threat levels.

Note: HG1 and HG2 call for six shots per panel, per threat.  

Note: RF1 and RF2 call for three shots per panel, per threat.  

Note: RF3 can be tested at one, two, or three shots per panel, at the manufacturer’s discretion.

NIJ 0101.07 goes a long way towards ensuring that rated hard armor stops common threats.  If there is a downside, it’s only that product testing and certification is becoming much more expensive for manufacturers, which might raise costs.  The Adept Storm Foundation is a good example of an RF1-compliant plate, the Mantis and Thunder are good examples of RF2-compliant plates, and the Colossus exceeds RF3.

There are other ways of doing things.  In Europe, VPAM is often used for body armor certification.  Unlike the NIJ’s specifications, which are product type specific, VPAM has one rating system that applies towards everything — it’s used for body armor, helmets, vehicles, and more.

VPAM:

VPAM 1
Protection: .22 Long Rifle
Bullets: 2.6±0.1 g (40±1.54 gr) .22 Long Rifle lead round-nose at 360±10 m/s (1181±33 ft/s)

VPAM 2
Protection: 9×19mm Parabellum
Bullets: 8.0±0.1 g (123±1.54 gr) 9×19mm Parabellum DM41 FMJ round-nose lead-core at 360±10 m/s (1181±33 ft/s)

VPAM 3

Protection: 9×19mm Parabellum
Bullets: 8.0±0.1 g (123±1.54 gr) 9×19mm Parabellum DM41 FMJ round-nose steel-jacketed at 415±10 m/s (1361±33 ft/s)

VPAM 4
Protection: .357 Magnum, .44 Magnum
Bullets:
10.2±0.1 g (157±1.54 gr) .357 Magnum at 430±10 m/s (1410±33 ft/s)
15.6±0.1 g (157±1.54 gr) .44 Magnum at 440±10 m/s (1443±33 ft/s)

VPAM 5
Protection: .357 Magnum semi-AP
Bullets: 7.1±0.1 g (109±1.54 gr) .357 Magnum solid-brass at 580±10 m/s (1902±33 ft/s)

VPAM 6

Protection: 7.62×39mm
Bullets: 8.0±0.1 g (122±1.54 gr) 7.62×39mm PS MSC at 720±10 m/s (2362±33 ft/s)

VPAM 7
Protection: 5.56×45mm, 7.62×51mm Ball
Bullets:
4.0±0.1 g (62±1.54 gr) 5.56×45mm SS109/US: M855 FMJ at 950±10 m/s (3116±33 ft/s)
9.55±0.1 g (147±1.54 gr) 7.62×51mm DM111 steel-core at 830±10 m/s (2723±33 ft/s)

VPAM 8
Protection: 7.62×39mm AP
Bullets: 7.7±0.1 g (118±1.54 gr) 7.62×39mm BZ API (armor-piercing incendiary) at 740±10 m/s (2427±33 ft/s)

VPAM 9

Protection: 7.62×51mm AP
Bullets: 9.7±0.2 g (149±3.08 gr) 7.62×51mm P80 armor-piercing bullets at 820±10 m/s (2690±33 ft/s)

VPAM 10
Protection: 7.62×54mmR AP
Bullets: 10.4±0.1 g (160±1.54 gr) 7.62×54mmR B32 API bullets at 860±10 m/s (2821±33 ft/s)

VPAM 11

Protection: 7.62×51mm AP-WC
Bullets: 8.4±0.1 g (129±1.54 gr) 7.62×51mm Nammo AP8/US M993 armor-piercing bullets at 930±10 m/s (3051±33 ft/s)

VPAM 12
Protection: 7.62×51mm AP-WC, heavy
Bullets: 12.7±0.1 g (196±1.54 gr) 7.62×51mm RUAG SWISS P AP armor-piercing bullets at 810±10 m/s (2657±33 ft/s)

VPAM 13
Protection: 12.7×99mm AP
Bullets: 43.5±0.1 g (671±7.71 gr) 12.7×99mm RUAG SWISS P penetrator bullets at 930±10 m/s (3051±33 ft/s)

VPAM 14

Protection: 14.5×114mm AP
Bullets: 63.4±0.1 g (978±7.71 gr) 14.5×114mm B32 API bullets at 911±10 m/s (2988±33 ft/s)

Note:  Three shots are placed on each armor panel during testing, regardless of threat level.

Note:  Backface deformation is measured, and up to roughly 50mm is allowed in body armor applications.  When VPAM is adapted for helmet testing, the limits are much more strict, corresponding very roughly to 10-12mm.

Generally, soft armor and helmets are rated to VPAM 3; rarely to VPAM 4; almost never to VPAM 5.  

VPAM 6 corresponds roughly to the NIJ’s 0101.06 Level III.  VPAM 7 corresponds to 0101.07 RF2.  VPAM 8 and 9 are intermediate light-AP levels.  VPAM 10 is analogous to the NIJ’s Level IV/RF2.  VPAM 11 and 12 are “stretch goals” for ultra-AP rated hard armor plates, but are most frequently used in vehicular armor.  The Colossus will withstand all threats up to and including VPAM 12.  VPAM 13 and 14 are intended solely for vehicular armor.

When looking at armor, check its rating and the specification or system it was rated under.  If it’s “Level III,” note that it might not stop all common rifle ball rounds.  If it’s “III+,” check to see if it’s also rated for M193 or M855 at muzzle velocity.  If it’s “Level IV,” it’ll probably stop any small arms threat you’re likely to encounter. 

Different materials have different performance characteristics, and there’s a lot you can learn simply by taking into account what any given plate is made of.  Continue reading for more on that score.

Hard armor 

Hard armor plates come in three basic varieties:  Ceramic composite, UHMWPE composite, and steel.  A short overview of each type follows.

Ceramic composite plates.  

These plates are made in two parts.  The primary component is a layer of a technical ceramic such as alumina, silicon carbide, or boron carbide. These ceramics are brittle, and must be bonded to a secondary component — a backup layer — which is made of a ductile and tough material.  In practice, this backup layer is usually a fiber composite.  If the ceramic is not paired with a backup layer, it will fail in tension — and, for all intents and purposes, simply shatter —  as soon as it is impacted by any bullet.  The backup layer prevents tensile failure, so the ceramic is forced to fail in compression, and this is the secret to the performance of ceramic armor: Although ceramics are brittle and have low tensile strengths, they have extremely high compressive strengths, and, if an armor plate is built properly, it will bring the compressive strength of its ceramic layer into play. 

Ceramic composite plates offer good protection against all small arms threat types, though the degree of protection they offer depends largely on the composition and thickness of their ceramic layer.  Ceramic composite plates can be damaged if dropped or handled excessively roughly, but most well-designed armor plates incorporate foam layers to minimize this risk.  Generally, ceramic armor plates are rated to “Level III+”/RF2 or Level IV/RF3.

Pros:

– Good performance-to-weight ratio.

– Unrivaled performance against steel-cored and AP threats.

– Generally lightweight.

Cons:

– Multi-hit performance can be, at times, unpredictable.

– Thick, at 0.75” to 1.25”.

– Relatively fragile.

General points:

– There are a few different types of ceramic in common use.  With respect to their selection and utilization, there are two general rules:  First, the ceramic layer must be harder than the projectile’s core. This rule has removed silicates and many oxides from contention as armor materials.  Second, against AP threats in particular, it is axiomatic that the ceramic layer needs to be thicker than the projectile core’s diameter.  This rule places hard limits on the theoretical mass of hard armor systems.

– In high-end armor systems, the composite backer generally makes up one-third of the armor plate’s total mass, with the ceramic strike-face making up the remaining two-thirds of that same plate’s mass.  In lower-end systems that utilize heavier ceramic materials, the ceramic layer can make up three quarters of the plate’s total mass, or more. 

– “Level III” ceramic armor plates are rated to stop six rounds of 7.62x51mm M80 Ball.  Without any known exceptions, these same plates will also stop 7.62x39mm MSC, 5.56x45mm M193, and 5.56x45mm M855.  As such, currently-available Level III ceramic armor plates are compliant with the National Institute of Justice’s forthcoming “RF2” specification for body armor, and are capable of stopping all common domestic rifle threats. 

– “Level IV” ceramic armor plates are rated to stop one round of .30-06 AP M2.  With very few exceptions, however, these plates will almost always exceed their rated capability and stop more than one round.  A Level IV plate will also stop all of the aforementioned “RF2” threats, and will also stop standard-issue military EPR rounds such as the M80A1 and M855A1.  

– NIJ-certified plates are required to withstand two drop tests, where the plate is slammed into a hard surface from a height, prior to ballistic experiments.  The US military, and other militaries, utilize similar drop test protocols.  For this reason, most ceramic plates include a thick foam layer on their strike-faces.  Properly made ceramic plates can certainly fracture and degrade if they’re mistreated, and any ballistic impact will assuredly degrade their performance, but they’re not exactly fragile. They’re built to survive hard knocks and stand up to rough handling and hard use.  

– Of all armor types, ceramic-faced armor offers the poorest and least predictable multiple hit performance characteristics.  Some manufacturers attempt to remedy this with “mosaic-style” ceramic strike faces, where the strike face is comprised of multiple smaller ceramic tiles, e.g. in a grid of hexagonal or rectangular tiles.  Done properly, this can dramatically improve a ceramic armor plate’s multi-hit performance, and its damage tolerance, at a significant penalty to its thickness and performance-to-weight ratio. 

– As mentioned above, ceramic armor systems generally consist of a ceramic layer over a fiber composite layer.  The function of the ceramic component — which always exhibits high hardness and compressive strength — is to shatter, deform, or erode the incoming projectile.  The fiber-composite backup layer has three functions: First to support the ceramic layer so it doesn’t fail in tension and instead is forced to fail in compression.  Second, to catch the shattered ceramic and bullet debris.  Third, to absorb whatever residual kinetic energy remains, which is done primarily via the plastic deformation of the backing layer. 

UHMWPE plates

These are thick plates made of ultra-high molecular weight polyethylene (UHMWPE) fiber composites.  These plates exhibit an extremely good performance-to-weight ratio against lead and mild-steel-cored ball rounds, but perform poorly against rounds with harder steel cores, such as the M855.  UHMWPE plates are extremely tough and chemically stable, but can degrade if exposed to very high temperatures for extended periods of time. 

Pros:

– Exceptional performance against lead-cored and mild steel cored rifle threats.

– Good multi-hit performance.

– Impact resistant.

– Can be extremely lightweight.

Cons:

– Very weak to threats with hardened steel cores or penetrators.  

– Generally as thick as ceramic armor plates.

– Can degrade if exposed to temperatures over 158°F (70°C) for extended periods of time.

General points:

– Hard armor plates made of UHMWPE, without a hard strike face, were introduced commercially around the year 2001, more than twenty years ago as of this writing.  Such plates generally exhibit extremely good performance against soft-cored ball rounds.  Indeed, as far back as 1996, a few years before UHMWPE materials really started to catch on, UHMWPE hard plates were identified as the lightest weight armor options for defeating certain rifle ball round threats, such as the 7.62x51mm M80 Ball and 5.56x45mm M193. [6] 

– UHMWPE-based hard armor plates are thick, at 0.9” to over 1.1” for NIJ Level III protection.  In these plates, against soft-cored ball round threats, the top 1/3^rd of material functions in much the same way as the ceramic layer in a ceramic-composite plate:  It disrupts and deforms the projectile.  The underlying layers of material then serve to catch metal fragments and absorb residual kinetic energy by converting it to plastic deformation, fiber strain energy, heat, etc.

– Because UHMWPE-based hard armor plates can’t disrupt or deform projectile cores that are made of hard steel, to say nothing of still harder materials, these plates are weak to threats with steel cores or penetrators, such as M855.  The Level IV (RF3) and RF2 ratings are effectively impossible for UHMWPE-based plates without hard strike faces to attain.

– UHMWPE plates are remarkably impact resistant and resilient, but care must be taken due to the fact that they can degrade if regularly or continually exposed to very high temperatures.

Other hard armor plate types:

Titanium composite armor:  Exemplified by the Adept Armor “Mantis” plate, titanium composite armor combines the core virtue of steel armor — toughness — with the performance characteristics of ceramic armor.  Like ceramic armor — and unlike UHMWPE and steel body armor — the Mantis is tested in compliance with the RF2 threat rating.  However, it must be noted that a titanium strike face thick enough to defeat the .30-06 APM2 would be excessively thick and heavy.

Flexible rifle armor:  Exemplified by DragonSkin, Hexar, and LIBA, this type of armor generally consists of an array of discrete ceramic elements over a thick, integral, soft armor backer.   Because the backer is soft rather than pressed, this variety of armor is flexible.  The discrete ceramic elements can come in any number of shapes, sizes, and arrangements.  DragonSkin utilized an array of overlapping discs.  Hexar utilizes a tessellated array of hexagons.  LIBA utilizes an array of cylindrical pellets, which may have fins which allow them to interlock.  Flexible rifle armor is similar to mosaic-style armor in that, when compared to monolithic ceramic armor, it offers improved multiple-hit performance at a penalty to its thickness and performance-to-weight ratio.  It may also be more comfortable, for it is not exactly “hard,” and can conform to the wearer’s body shape.

NovaSteel:  Adept Armor has pioneered the development of steel armor systems that (a) work exceedingly well at a low thickness and light weight against handgun and fragmentation threats, and (b) exhibit good performance against rifle threats without suffering from the drawbacks traditionally associated with legacy steel body armor systems.  The NovaSteel helmet, buckler, and breastplate are presently available, and more items are planned for the NovaSteel line.

Hard Body Armor Cuts:

Body armor torso plates generally come in four different cut types.

The full cut is rectangular, often with clipped or rounded corners, and is usually intended for use as a rear plate.  (More on this later.)  It is the largest of the plate cuts.  A full cut 10×12” armor plate has a surface area of very nearly 120 square inches, and, if it has an areal density of 6 pounds per square foot, weighs 5 pounds.

The SAPI cut, which is the most popular and widespread body armor cut, is a design modeled after the US military’s SAPI body armor plates.  In SAPI cut plates, the top corners have been cut at 45 degrees from the diagonal, to enable better shoulder mobility and facilitate the use of small arms.  A 10×12” SAPI cut plate has a surface area of approximately 108 square inches, and if made from the same 6 psf material as our full-cut plate, weighs 4.5 pounds.

The shooter’s cut is very similar to the SAPI cut, but the top corners are cut away at a slightly steeper angle, which makes the plate lighter and enables more shoulder mobility, though it sacrifices some coverage.  This cut is not standardized, and varies from manufacturer to manufacturer.  Generally, a 10×12” shooter’s cut has a surface area of around 100 square inches, and weighs slightly less than an otherwise identical SAPI cut plate — in this case, at the 6 psf of our previous examples, around 4.2 pounds.  

The swimmer’s cut is generally along the same lines as the shooter’s cut, but the top corners are cut at an even steeper angle which extends further down the plate.  This is a fairly uncommon cut, and can usually be considered a variant of the shooter’s cut.  We use the word “generally” in the first sentence here because there’s really no clear definition of what this term means; sometimes “shooter’s cut” and “swimmer’s cut” are interchangeable.  

What body armor cut you select comes down largely to personal preference.  Rectangular plates should not, however, be used in front.  And note that swimmer’s cut plates often sacrifice a lot of protective coverage, yet don’t provide much better shoulder mobility than SAPI cut or Shooter’s cut plates, so the trade-off might be a poor one.

Hard Armor Plates: Weighing the Pros and Cons

There are drawbacks associated with every armor type.  The world’s top militaries have carefully considered the advantages and disadvantages of each, and have come to favor ceramic composite armor.  UHMWPE-only plates are sometimes preferred for certain roles, e.g. for light infantry — and can be quite useful in certain situations, e.g. in littoral, riverine, and maritime operations — but their use is not widespread.  Steel body armor plates are, generally, not in military service at all.  Titanium-UHMWPE composite plates are an emerging category that may see wide use in the near future.  

1. 1.See, e.g.: Manning, Russell J. E. (2006). Temperature in Cars Survey, Brisbane.  RACQ Vehicle Technologies Department.
2. 2.All common armor ceramics — from alumina to boron carbide — are harder than the tool steel cores of AP projectiles such as the .30-06 APM2.  However, armor ceramics are not always harder than the cemented tungsten carbide cores of more advanced AP projectiles such as the 7.62x51mm M993, and this can result in poor performance. 
3. 3.This places a practical lower bound on ceramic armor tile thickness.  But because armor plates are built with a margin of safety in mind, the thicknesses employed are almost always greater than that.
4. 4.Because small tiles don’t form proper fracture conoids upon impact.  See the entry for “fracture conoid” in our Knowledgebase’s Glossary for more on this. 
5. 5.See, e.g.: Liu, Xiaoyan & Yu, Weidong. (2005). Evaluation of the tensile properties and thermal stability of ultrahigh-molecular-weight polyethylene fibers. Journal of Applied Polymer Science. 97. 310 – 315. 10.1002/app.21720.
6. 6.Verlinde, A.S., van Dingenen, J.L.J., Dyneema Inserts: Personal Armor Against Rifle Bullets, Proceedings of Personal Armor Systems Symposium 96, Colchester, UK, Sep 1996