ESAPI Vs. SAPI: What Is the Difference Between Them?

Safety, precision, and functionality all must come with quality body armor. Even though the body armor industry is regularly filled with many brands and competitive materials, two body armor types stand out as pillars of excellence: ESAPI and SAPI. Deciding which one is best for you is an important decision that needs careful consideration. Both ESAPI and SAPI body armor are made for small arms bodily defense. ESAPI is heavier by 27% and provides more robust protection against armor-piercing rounds than SAPI. They are both the same shape. 

The United States military began phasing out the SAPI body armor in favor of ESAPI body armor, which should tell you something right there. If you have ever wondered about the dimensions, strength, build, or construction of these two premiere body armor styles, read on to find out more. 

The Main Differences Between ESAPI and SAPI Body Armor

The acronym SAPI stands for Small Arms Protective Insert, whereas ESAPI stands for Extended Small Arms Protective Insert. The differences are minor in the name but huge in the performance of each of these tactical body armor inserts. Although ESAPI and SAPI are body armor inserts you might see placed in backpacks or sleeves, these body armor inserts for jackets are reliable and incredibly popular. 

Body armor is made for defense against munitions. The reason you need body armor is for physical safety from different levels of ballistics threats. SAPI, ESAPI, and every other cut of body armor have their own rate of protection. SAPI is an excellent body armor that provides quite adequate protection against small arms fire. However, ESAPI has enhanced security; it’s in the name and can defend against the greater force of armor-piercing munitions. 

To break down the main differences between the two types of body armor, you need to view their statistics side by side. The chart below details the weight, impact ratio of defense, size, cost, and material construction along with a verdict of which is better of the two so that you get a clear picture of this evolution in body armor. 

Weight27% heavier than SAPILightweightSAPI: Lighter than ESAPI and more comfortable to maneuver in
NIJ Threat ProtectionIVIIESAPI: The body armor stops armor-piercing bullets fired at high velocity from rifles
SizeExtra Small: 7.25″ x 11.5″Small: 8.75″ x 11.75″Medium: 9.5″ x 12.5″Large: 10.125″ x 13.25″Extra Large: 11″ x 14″Extra Small: 7.25″ x 11.5″Small: 8.75″ x 11.75″Medium: 9.5″ x 12.5″Large: 10.125″ x 13.25″Extra Large: 11″ x 14”Same
Material ConstructionBoron Carbide Silicon CarbideESAPI:  boron carbide is one of the strongest armor materials and is even used on armored vehicles
(Source: Spartan Armor Systems)

As you can see, the main difference between these two body armors is weight.  Even though the military used SAPI body armor for years, it did not hold up against high-powered rifle fire. Now military personnel use a stronger body armor that is called ESAPI. The construction materials for this stronger body armor are slightly different but essential to take note of. It is because of these materials that it is more potent but also heavier. Read on to find out more about what makes body armor stronger. 

How ESAPI Body Armor is Stronger?

ESAPI body armor inserts are made stronger by the mixture of materials they are composed of. The main ingredient for body armor inserts like SAPI or ESAPI is known as “black diamond” or boron carbide. When mixed with softer materials like polyurethane or silicone, the body armor plate is more resistant to ballistics. 

The ESAPI body armor is stronger because of the mixture of polyurethane and boron carbide. The plates are generally heavier than SAPI plates because of the greater density of boron carbide in the plate’s composition. Both SAPI and ESAPI body armor are built to use with a body armor jacket and under the soft liner. However, ESAPI is stronger because it has more boron carbide in its manufacturing and because it is mixed with polyurethane.
Manufacturing process of Ballistic plates | Protection Group Danmark

NIJ Threat Protection Levels and Where ESAPI and SAPI Stand

The National Institute of Justice puts out ballistic standards for body armor on a rating scale. This scale details the maximum round size and ballistic force that a plate of body armor can withstand without allowing penetration. The most recent standards were put out in 2008 and called Standard 0101.06.  This chart details the classifications for personal body armor types based on the level of ballistic performance. The classification is based on the number that should be the minimal protection on any part of the body armor. The classification from NIJ also deals with distances and angles that the ballistics are shot from. 

Body Armor TypeMaximum Caliber/Force Armor Can Withstand
IIA9mm full metal jacket, with a mass of 8 grams at a velocity of 1225 ft/second.40 caliber S&W full metal jacket, the mass of 11.7 grams at a velocity of 1155ft/second
II9mm full metal jacket, with a mass of 8 grams at a velocity of 1305 ft/second.357 Magnum jacketed soft point with a mass of 10.2 grams at a velocity of 1430 ft/second
IIIA.357 SIG full-metal jacket Flat Nose with a mass of 8.1 grams at a velocity of 1470 ft/second.44 Magnum semi-jacketed hollow point with a mass of 15.6 grams at a velocity of 1430 ft/second
III (hard armor or plate inserts)7.62 mm full metal jacket steel jacketed(M80) with a mass of 9.6 grams at a velocity of 2780 ft/second
III (soft/flexible armor)7.62 mm full metal jacket steel jacketed(M80) with a mass of 9.6 grams at a velocity of 2780 ft/second
IV (Armor Piercing Rifle).30 caliber armor-piercing bullets (M2 AP) with a mass of 10.8 grams at a velocity of 2880 ft/second
(Source: National Institute of Justice)

As you can see, the significant differences between ESAPI and SAPI body armor come down to the level of protection and the weight difference. ESAPI provides defense from a high-powered rifle shot and is ranked as an NIJ protection level IV body armor, the NIJ’s highest ranking. Meanwhile, the SAPI body armor is only rated a level II on the NIJ Threat Protection, capable of stopping a 9mm or .357 full metal jacket bullet. Either of these body armor types is sufficient for their level of threat protection. However, it is vital to assess your needs for safety before making a decision. Read on for a more detailed breakdown of when to use ESAPI body armor versus when to use SAPI body armor.

When to Use SAPI Body Armor?

Body armor transforms your confidence and peace of mind. Defense with body armor leads you into so many different avenues. It isn’t easy to know if you picked the right type of protection for your situation. Small arms protection is vital if you are in law enforcement, close range, or at risk of being under fire from small-caliber handguns. SAPI body armor is an excellent choice for many different reasons. If you perceive threats with ballistics in the theater of war or on the beat as a first responder, you may want SAPI body armor. See below for some of the most common times when you may wish to use SAPI Body armor. 

When You Hold a Small Arms Weapon Yourself

Many jobs that are not first responders deal with dangerous situations where you may want a side-arm to protect yourself or deter danger. However, if you carry a side-arm, there is a chance that the weapon could be taken from you and used on you. In this case, you want protection from the power of your own gun. When you hold a small arms weapon yourself, you want SAPI body armor. SAPI body armor helps avoid damage and injury from getting shot by someone who takes your gun. Some of the most common jobs and situations where SAPI body armor would help protect you from becoming a target from your own small arms weapon are:

  • If you are a money delivery person moving around on routes that are planned out in advance; in a situation with money that is vulnerable or could be a target of robbers
  • If you are a security guard in a stationary position for most of the time; if your guard route is predictable, or you are alone
  • If you are a visible beat police officer patrolling the city’s streets, your gun in plain view makes you a target for bad people to take your weapon.

When You Need Mobility

By this point, we know that SAPI body armor is weaker than ESAPI. However, since the plates are thinner and made with lighter material, they weigh almost 27% less than ESAPI body armor inserts. More lightweight body armor, such as SAPI plates, are ideal for certain situations where you need mobility. Having the mobility to escape, moving from being under fire to safety, pursuing engagements, or performing physical tasks in strenuous events makes up for the body armor’s inability to withstand high powered rifle ballistics. 

Sometimes, maneuvering, mobility, and speed are more important. Below are some of the situations or tasks you might perform where lighter SAPI body armor is the right choice. 

  • As a patrol police officer on a bike, on foot, or engaged in raids
  • As a delivery person who may need to escape dangerous situations
  • As a combat soldier in tactical urban environments where strenuous physical maneuvering is essential

When You are Primarily Indoors

Some people who wear body armor want to remain discreet. If you are in a high stakes job where danger is possible, you want to stay safe. Drawing attention to yourself might bring a dangerous call. So, it is essential to protect yourself with body armor that does not draw attention. Light body armor plates, such as those made in the SAPI design, are perfect for keeping a low profile. You can even place SAPI body armor plates in backpacks, briefcases, or on your person in various locations. 

Some of the instances where people who have jobs that are indoors and need discretion with their body armor like a SAPI design might be: 

  • Lawyers around convicted criminals
  • Judges with high profile cases
  • Teachers in violent school districts
SAPI body armor helps avoid damage and injury from getting shot by someone who takes your gun (Source).

When to Use ESAPI Body Armor?

As one of the most vital body armor inserts plates, ESAPI body armor is rated a type IV by the NIJ. This body armor is powerful and extremely heavy. If you need the extra protection that is also used on armored vehicles, ESAPI is an excellent choice. When you might need the added protection of ESAPI body armor inserts, some of the situations are listed below. Read on to find out more about the dangerous conditions that might necessitate body armor like ESAPI that can turn away a high-powered rifle’s ballistics. 

Military Personnel Dealing with Enemy Combatants 

Most military outposts moved over from SAPI body armor inserts to ESAPI for all soldiers in the theater of war years ago. The added weight is nothing compared to the type of security afforded to their troops. A sad and frightening truth about the military is that high powered rifle fire is a common threat and occurrence. Military personnel are actively engaging enemy combatants on the field of war. So, it makes sense that ESAPI is the body armor insert of choice since they face such substantial threats on a daily basis and from any direction. Troops are much closer to fully protected by ESAPI body armor. They are engaged in various situations because of their added protection with ESAPI.  

Law Enforcement in High Crime Areas or Rural Areas

Law enforcement on the streets might encounter high powered rifles or automatic gunfire at any time. This gives ESAPI a place of pride in the field of law enforcement. Although the occurrences are rare, the added security is definitely needed in some cases, and it is better safe than sorry. Rural areas where hunting takes place might offer dangerous scenarios for law enforcement officers. ESAPI body armor is essential for areas where they are more high-powered weapons owned and used by the general public. 

It should be obvious that certain high powered hunting rifles are generally used for recreation. However, suppose a high-powered rifle is placed in the wrong hands. In that case, these weapons turn into effective killing machines with the highest level of danger for law enforcement. In these circumstances, law enforcement personnel require ESAPI body armor for their protection. 

As one of the most vital body armor inserts plates, ESAPI body armor is rated a type IV by the NIJ (Source).

What Are SAPI and ESAPI Body Armors Made of

Both SAPI and ESAPI body armor are made out of a man-made material called boron carbide. The material of boron carbide is challenging and is the second hardest man-made material. Boron carbide is made easily in large quantities and is also called black diamond. The only problem with body armor made from boron carbide is the incredible weight and breakage on impact.

On its own, boron carbide is very effective against handguns that fire bullets at or under 900 ft/second. However, bullets fired at higher velocities tend to break the boron carbide. That is until scientists found that adding silicone to boron carbide strengthened it considerably. Now, both SAPI and ESAPI contain a mixture of boron carbide and silicon in different quantities. ESAPI body armor is 27% heavier than SAPI body armor. Although both are classified as protective inserts, ESAPI is made with a Polyurethane mixture. SAPI is made with a monolith or silicone mixture. Both are lighter than traditional ceramic body armor but are much more expensive. 

The fundamental details about SAPI and ESAPI materials are the mixture of boron caribe with other lighter and more flexible materials. These materials actually added some give to the body armor plate, making them more durable to ballistics. The difference between the two is the proportions of boron carbide in each mixture, either allowing for more strength in ESAPI or flexibility and lightness in SAPI. 

Body Armor Shape Comparison

SAPI and ESAPI body armor designs are unique to their construction. As one of the most protective body armor designs ESAPI and SAPI body armor is also the most restrictive. It is no wonder that many who need flexibility and maneuverability do not prefer ESAPI or SAPI to other designs and body armor cuts. 

SAPI/ESAPI Body Armor Shape

SAPI and ESAPI body armor are shaped like a shield with rounded corners at the top. There is little room on the sides or bottom of this body armor. The lack of space on the sides and corners of ESAPI and SAPI limits the range of movement. The lack of motion ability is because of the corners’ design. Squared off corners like those in other designs allow for movement. However, the corners are squared off in this design instead of the cutaway. The rectangular shape of the bottom half makes a movement with the lower body very troublesome. Although it has the most coverage of all body armor cuts, ESAPI and SAPI are challenging to move in. 

Shooter’s Cut Body Armor Shape

With a shooter’s cut body armor, the shoulders are afforded more range of motion. The entire body armor plate is large and shield-shaped, like ESAPI body armor. However, the top corners are cut away more in the shooter’s cut. These cuts at the shoulders allow for holding arms up to fire while still protecting most of the body from direct hits. 

Triple Curve Cut Body Armor Shape

Based on the same innovation of the shooter’s cut body armor, a triple curve body armor has corners cut for movement. Both the top and bottom corners of the body armor are cut away to allow for more mobility with the shoulders and the lower body in the hips. The armor is also form-fitting, which is comfortable and more stable. Form-fitting body armor like this one has curves built into it. The triple curve cut has an angle into the top of the chest, around the abdomen, and down into the waist. 

Swimmer’s Cut Body Armor Shape

This body armor cut has the name “swimmer” because of the great range of motion it affords all corners of the body. Other body armor cuts’ shield shape is gone in favor of a diamond-shaped and tapered design cut. Long narrow cuts from the middle of the body armor plate taper up to the top and allow for the body armor cut’s most shoulder range of motion. 

Body armor shape comparison (Source).

Tips for Taking Care of Your Body Armor

ESAPI and SAPI body armor are notoriously more fragile than other body armors from earlier generations. However, their strength is excellent, and they tend to weigh less than these previous generations. In the end, as long as you take good care of your ESAPI and SAPI body armor, you should be better protected from gunfire than with older designed body armor plates. Read on to learn more about some of the best tips for taking care of your ESAPI and SAPI body armor.

Wear and Tear Matters More Than Age

Even though body armor like SAPI and ESAPI have similar age limits of around five years of active duty, that age restriction matters less for armor that is not taken care of. SAPI and especially ESAPI body armor are made from materials that tend to wear out if used and stored roughly. 

Even if the body armor is still within the time that it is deemed acceptable for use in the field, it needs constant monitoring for damage. Body armor used daily wears out faster than armor used only occasionally, making it less effective than its rarely used counterpart. 

Some of the most common damages that are detected on SAPI and ESAPI body armor which could make the body armor less effective at stopping ballistics are: 

  • Visible dents or dents that can be easily felt 
  • Creases in the material that show discoloration
  • Tears in the material 
  • Smells in the material; this could indicate that the fabric got wet, which damages and weakens your body armor
  • Burns such as from cigarettes, fires, gunfire, or other heat sources

Clean Your Body Armor and Body Armor Carrier

Dirt that gets into the body armor carrier pockets grinds into the body armor and wears it down slowly over time. Make sure you have two body armor carrier vests: one you wear the body armor in and one you clean at the end of the previous use. You also want the body armor clean before putting it in the new carrier. Before you place your body armor plates in the carrier pockets, use a sponge to dab off any dust, dirt, lint, or other particles. Dry the body armor thoroughly with a dry clean cloth, not a paper towel. Then insert the plates into the body armor carrier. Cleaning your body armor protects the tiny fibers of the material. If you neglect cleaning your body armor between uses, you risk shortening their life span and putting your life at risk. 

Stay Fit So Body Armor Fits

Staying fit as a law enforcement officer or soldier is a great idea at all times. However, remaining a consistent weight is also recommended by body armor manufacturers. Once you buy the size and fit of your body armor, you shouldn’t gain weight. In fact, body armor manufacturers warn that no one should gain more than ten percent of their original body weight while wearing body armor. 

Gaining excess weight makes your body armor ill-fitting. A bad fit for body armor means you are uncomfortable, and the body armor isn’t doing a good job protecting your vitals. Do yourself a favor and stay fit when wearing body armor regularly.  If you start noticing it feeling extra tight, get back to the gym as soon as possible! Otherwise, your vital organs might be exposed, and you will be stuck with expensive and uncomfortable body armor.

Cleaning Your Body Armor

In Conclusion

The protection you get from body armor will save your life if you let it. SAPI body armor was one of the most trusted body armor types globally for many years. However, this all changed when it was updated to the ESAPI, which the military adopted across the board. The enhanced protection from high powered rifle fire and the NIJ ballistics classification IV in the ESAPI design is a needed benefit that military personnel deserves. Hopefully, after reading this article, you will choose the body armor type right for your situation. Regardless, we hope you stay safe and informed about your body armor choice so that your life is better, your job is better, and your peace of mind is better.


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Kevin was born and raised in Texas and loves all things tactical. His hobbies include shooting, hunting, rock climbing, and hiking with his dog Jax.

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