Body Armour Certification Guide: KR1, SP1, EN388 & NIJ Standards Explained
Last updated: June 2026
Overview
For UK buyers, the definitive stab-proof standard is KR1/SP1 under the Home Office CAST 2017 testing regime. This is the benchmark used for UK police body armour — independently lab-tested at 24 joules of stab and spike force. KR1/SP1-certified armour has passed multi-angle, multi-strike testing in a UK-accredited laboratory and is listed on the Home Office Police Equipment Database (PED).
Important distinctions:
- EN388 is a European mechanical durability standard (abrasion, cut, tear, puncture). It tests the material's resistance to industrial hazards — it is NOT a stab-proof certification. A vest described only as "EN388 certified" has not been tested against knife or spike attacks at weapon-level force.
- NIJ 0115.00 is the US equivalent of KR1/SP1, using similar energy levels (24J–43J) but different test protocols.
- VPAM KDIW is the German standard, adding needle and blunt-impact protection to knife and spike testing.
Bottom line: A vest labelled "stab-proof" without a specific standard (KR1, SP1, NIJ 0115.00, or VPAM) and a test report from an accredited laboratory is not independently verified.
Why Certification Matters
Not all body armour is created equal. A vest labelled "stab-proof" means nothing without independent testing to a recognised standard. Testing confirms the armour has been evaluated in an accredited laboratory under controlled conditions — and passed.
Without certification, you are taking the manufacturer's word that their product will protect you.
This guide explains every major body armour testing standard relevant to the UK and European market:
| Standard | Region | What It Tests |
|---|---|---|
| CAST KR1/SP1 (Home Office 2017) | UK | Knife and spike resistance at weapon-level force |
| EN388:2016 | EU | Mechanical durability: abrasion, cut, tear, puncture |
| NIJ 0115.00 | USA | Stab and spike resistance for law enforcement |
| VPAM KDIW 2004 | Germany/EU | Knife, spike, needle, and blunt impact protection |
UK Home Office Standards: KR1, SP1 (CAST 2017)
What Are KR1 and SP1?
The UK Home Office sets the standards for body armour issued to police forces and government personnel. Originally defined under HOSDB 2007 (Publication 39/07) and updated under CAST 2017 (the current version, Publication 012/17), these standards define protection levels against edged and pointed weapons.
CAST stands for the Centre for Applied Science and Technology, the Home Office body responsible for protective equipment standards. The testing is conducted at UK-accredited independent laboratories.
| Code | Meaning | Threat Type | Examples |
|---|---|---|---|
| KR | Knife Resistance | Edged blades | Kitchen knives, hunting knives, craft knives |
| SP | Spike Resistance | Pointed weapons | Ice picks, shanks, screwdrivers, needles |
Armour can be certified for knife protection alone (KR1), spike protection alone (SP1), or both combined — KR1 + SP1 — which is the standard requirement for multi-threat body armour in UK policing and security.
Protection Levels and Test Energies
| Level | E1 Knife Energy | E1 Max Penetration | E2 Knife Energy | E2 Max Penetration | Spike Energy (SP) | Spike Max Penetration |
|---|---|---|---|---|---|---|
| Level 1 (KR1/SP1) | 24 Joules | 8.0 mm | 36 Joules | 20.0 mm | 24 Joules | 0 mm |
| Level 2 (KR2/SP2) | 33 Joules | 8.0 mm | 50 Joules | 20.0 mm | 33 Joules | 0 mm |
| Level 3 (KR3/SP3) | 43 Joules | 8.0 mm | 65 Joules | 20.0 mm | 43 Joules | 0 mm |
Source: Home Office CAST, Body Armour Standard 2017 (Publication 012/17).
Key points:
- E1 is the primary test — the energy level the armour must defeat with minimal penetration (≤8mm for knives, 0mm for spikes).
- E2 is the "overtest" — a 50% higher energy level simulating a worst-case scenario. Up to 20mm of penetration is permitted at E2 for knife strikes only.
- Spike penetration must be ZERO at all levels. Even a single millimetre constitutes a failure. This makes SP1 certification significantly more demanding than knife-only testing.
- All testing is multi-angle — strikes are delivered at 90° (perpendicular) and at angled orientations to simulate real-world attack variability.
- All testing is multi-strike — multiple impacts are delivered across the armour panel, including on seams and overlaps.
How CAST Certification Works (2025 Process)
As of May 2025, the Home Office formalised the certification process with Version 1.0 of the Test House SOP Guidance:
1. Manufacturer contacts a UK-accredited test house and submits a technical file with armour construction details, photographs, and stitching specifications.
2. Test house verifies all documentation and conducts testing per BAS17 requirements.
3. Critical Perforation Analysis (CPA) is calculated using the Home Office CPA tool.
4. If the armour passes, a Certificate of Accreditation (CoA) is drafted and submitted to the Home Office — not sent directly to the manufacturer.
5. If the armour fails, the model number cannot be reused for any future submission.
6. Passed certifications are published on the Police Equipment Database (PED) at ped-cast.homeoffice.gov.uk.
How to Verify KR1/SP1 Certification
1. Ask the seller for the certificate number and test house name.
2. Cross-reference on the PED database.
3. Verify the test report covers the specific model you are buying — not a different product from the same manufacturer.
4. Check the certificate date — certification does not expire, but manufacturing processes can change. Recent certifications (within 3 years) are preferable.
What 24 Joules Actually Means
A joule is a unit of energy. 24 joules is approximately the energy delivered by:
- A 1 kg mass dropped from 2.4 metres
- The strongest stab a 95th-percentile adult male can deliver with a knife (per the PSDB 1997–1999 stabbing energy study)
This means KR1/SP1 is designed to defeat the maximum force the vast majority of people can generate with a knife or spike — not an average strike, but the hardest realistic attack.
EN388:2016 — European Mechanical Protection Standard
What EN388 Tests
EN388:2016+A1:2018 is the European standard for protective gloves against mechanical risks. Its test principles are also referenced for protective clothing materials, including body armour fabrics. It tests four mechanical properties plus two optional additional ratings:
| Position | Test | Scale | What It Measures |
|---|---|---|---|
| 1st digit | Abrasion Resistance | 1–4 | Cycles to wear through the material |
| 2nd digit | Blade Cut Resistance (Coup test) | 1–5 | Resistance to a rotating circular blade under 5N load |
| 3rd digit | Tear Resistance | 1–4 | Newtons of force to tear the material |
| 4th digit | Puncture Resistance | 1–4 | Newtons of force to puncture with a standardised probe |
| 5th character | TDM Cut Resistance (ISO 13997) | A–F | Resistance to a single-stroke straight blade (2N–30N+) |
| 6th character | Impact Protection | P or blank | Pass/fail for impact-absorbing padding |
A typical EN388 rating looks like: 4 5 4 3 D P
The TDM Cut Test (ISO 13997) — The One That Matters for Body Armour
The original "Coup test" (2nd digit) has a major flaw: materials containing steel, fibreglass, or aramid fibres dull the rotating blade, producing unreliable results. The TDM-100 test (5th character, per ISO 13997) fixes this:
- Uses a fresh razor blade for every single cut
- Measures the force (in Newtons) required to cut through 20mm of material
- Much more relevant to body armour: a single sharp blade drawn once, not a rotating blade moving back and forth
| TDM Level | Force (Newtons) | Real-World Comparison |
|---|---|---|
| A | 2–4.9 | Minimal — light handling gloves |
| B | 5–9.9 | Low — general work gloves |
| C | 10–14.9 | Low–moderate — glass/metal handling |
| D | 15–21.9 | Moderate–high — assembly work, machine tools |
| E | 22–29.9 | High — waste handling, metal edges |
| F | 30+ | Extreme — heavy assembly, machining, stamping |
EN388 Is NOT a Stab-Proof Certification
This is the most common source of confusion. EN388 tests:
- Abrasion — rubbing against rough surfaces
- Cut — a blade drawn across the surface (industrial accident scenario)
- Tear — pulling the material apart
- Puncture — a standardised probe pressed through (NOT a knife stab)
None of these tests simulate a knife thrust or spike attack at weapon-level force (24+ joules). A vest marketed as "EN388 certified" without a separate KR1/SP1 or NIJ 0115.00 certification has not been independently tested against knife or spike attacks.
What EN388 IS useful for: It tells you the material has been tested for mechanical durability. A body armour fabric with EN388 Level 5 blade cut resistance and Level F TDM cut resistance uses a material that is demonstrably difficult to cut through — but this is a material property test, not a certification that the finished vest will stop a knife attack.
NIJ 0115.00 — US Stab Resistance Standard
Overview
NIJ Standard 0115.00 (*Stab Resistance of Personal Body Armor*) is the US Department of Justice standard for stab-resistant body armour. It is the nationally accepted standard for law enforcement and corrections officers in the United States.
The standard was developed using data from a PSDB study (1997–1999) that measured the stabbing force distribution across the male population. The energy levels correspond to the 85th, 90th, and 96th percentiles of maximum stabbing force.
Two Protection Classes
| Class | Symbol | Threat | Typical Environment |
|---|---|---|---|
| Edged Blade | Blue square | Machined knife blades | Street patrol, general duty |
| Spike | Green triangle | Improvised spike weapons, shivs | Corrections, prisons |
Armour is labelled with both a shape (indicating threat type) and a number (1, 2, or 3, indicating protection level).
Protection Levels
| Level | E1 Energy | E2 Energy (Overtest) | E1 Max Penetration | E2 Max Penetration | Population Percentile |
|---|---|---|---|---|---|
| 1 | 24 J | 36 J | 7 mm | 20 mm | 85th |
| 2 | 33 J | 50 J | 7 mm | 20 mm | 90th |
| 3 | 43 J | 65 J | 7 mm | 20 mm | 96th |
Source: NIJ Standard 0115.00, US Department of Justice.
NIJ vs CAST: Key Differences
| Aspect | NIJ 0115.00 | CAST KR1/SP1 |
|---|---|---|
| Jurisdiction | United States | United Kingdom |
| E1 knife penetration limit | 7 mm | 8 mm |
| Spike penetration limit | 7 mm | 0 mm |
| Test angles | 0° and 45° | Multiple angles inc. seams |
| Certification body | NIJ-approved labs | Home Office PED |
| Public database | NIJ Compliant Products List | PED website |
The UK CAST standard is more stringent on spike protection (0mm vs 7mm allowed penetration) and tests at more angles including seam strikes. Armour that passes KR1/SP1 would generally pass NIJ Level 1, but the reverse is not necessarily true — especially for spike protection.
VPAM KDIW 2004 — German/European Standard
Overview
VPAM KDIW 2004 (current edition: May 2011) is the German test standard for stab and impact-resistant protective equipment, published by the Association of Test Laboratories for Attack-Resistant Materials and Constructions (VPAM), based at the German Police University in Munster.
VPAM is unique among body armour standards in testing four distinct threat types under one standard:
| Code | German | Threat | Examples |
|---|---|---|---|
| K | Klinge | Knife (blade) | Edged weapons |
| D | Dorn | Nail/Spike | Pointed weapons |
| I | Injektion | Injection cannula | Hypodermic needles |
| W | Wurfel | Block/Impact | Thrown or swung objects with edges |
Protection Classes
| Class | Knife Energy | Spike Energy | Needle Energy | Max Penetration |
|---|---|---|---|---|
| K1/D1 | 25 J | 25 J | — | < 20 mm |
| K2/D2 | 40 J | 40 J | — | < 20 mm |
| K3/D3 | 65 J | 65 J | — | < 20 mm |
| K4/D4 | 80 J | 80 J | — | < 20 mm |
| I1 | — | — | 2.5 J | 0 mm |
The Needle Test (I1) — A Unique Differentiator
VPAM is the only major standard that tests against hypodermic needle attacks (21G cannula, 2.5 joules strike energy). The requirement is zero penetration — the needle must not puncture through the material. This is particularly relevant for:
- Prison and custody officers (needle threats are common in correctional settings)
- Healthcare security staff
- Anyone concerned about blood-borne pathogen transmission via needle attack
Block/Impact Protection (W)
VPAM also tests impact protection against thrown or swung objects with edges (blocks, bricks, hammers):
| Class | Impact Energy | Max Deformation |
|---|---|---|
| W1 | 15 J | < 20 mm |
| W2 | 25 J | < 20 mm |
| W3 | 40 J | < 20 mm |
| W4 | 65 J | < 20 mm |
| W5 | 100 J | < 20 mm |
This is relevant for public-order policing, security at protests or large events, and environments where blunt weapons may be used.
Full Comparison: All Standards at a Glance
| Feature | CAST KR1 | CAST KR2 | CAST KR3 | NIJ Level 1 | NIJ Level 2 | NIJ Level 3 | VPAM K1 | VPAM K2 | VPAM K3 | VPAM K4 |
|---|---|---|---|---|---|---|---|---|---|---|
| Knife E1 energy | 24 J | 33 J | 43 J | 24 J | 33 J | 43 J | 25 J | 40 J | 65 J | 80 J |
| Knife E2 energy | 36 J | 50 J | 65 J | 36 J | 50 J | 65 J | — | — | — | — |
| Spike energy | 24 J | 33 J | 43 J | 24 J | 33 J | 43 J | 25 J | 40 J | 65 J | 80 J |
| E1 knife penetration | ≤8 mm | ≤8 mm | ≤8 mm | ≤7 mm | ≤7 mm | ≤7 mm | <20 mm | <20 mm | <20 mm | <20 mm |
| E1 spike penetration | 0 mm | 0 mm | 0 mm | ≤7 mm | ≤7 mm | ≤7 mm | <20 mm | <20 mm | <20 mm | <20 mm |
| Needle protection | No | No | No | No | No | No | I1: 0mm | I1: 0mm | I1: 0mm | I1: 0mm |
| Impact protection | No | No | No | No | No | No | W1–W5 | W1–W5 | W1–W5 | W1–W5 |
| Multi-angle | Yes | Yes | Yes | 0°, 45° | 0°, 45° | 0°, 45° | Yes | Yes | Yes | Yes |
| Seam testing | Yes | Yes | Yes | No | No | No | Yes | Yes | Yes | Yes |
How to Verify Any Body Armour Certification
1. Ask for the certificate number. A legitimate certification has a traceable reference number.
2. Identify the test house. Find out which independent laboratory conducted the testing.
3. Cross-reference. For KR1/SP1, check the Home Office PED database. For NIJ, check the NIJ Compliant Products List.
4. Match the model. Verify the certificate is for the exact model you are buying — not a different product.
5. Check the date. While certifications do not technically expire, manufacturing processes, materials, and factory locations can change. A certificate more than 5 years old may not reflect the product currently being manufactured.
6. Beware of vague language. "Tested to [standard]" is not the same as "Certified to [standard]." Certification requires passing results from an accredited independent laboratory. "Tested to" could mean an in-house test with no independent verification.
ArmorLite Certifications
ArmorLite's body armour products are independently tested and certified:
| Product Line | Certification | Standard |
|---|---|---|
| FlexGuard Series | Level 1/KR1 + SP1 | NIJ 0115.00/CAST |
| SoftGuard Series | 3 x Level 4 | EN388:2016 |
All ArmorLite certifications are conducted by UK-accredited independent test laboratories. Certificate numbers and full test reports are available on request — contact customer@armorliteshop.com.
Sources
1. Home Office CAST, Body Armour Standard 2017 (Publication 012/17)
2. Home Office CAST, Test House SOP Guidance v1.0, May 2025
3. NIJ Standard 0115.00, Stab Resistance of Personal Body Armor, US Department of Justice
4. VPAM KDIW 2004, Prudfrichtlinie: Stich- und Schlagschutz, May 2011
5. EN 388:2016+A1:2018, Protective Gloves Against Mechanical Risks
6. ISO 13997:1999, Protective Clothing — Mechanical Properties — Determination of Resistance to Cutting by Sharp Objects
7. PSDB, Stabbing Energy Distribution Study, 1997–1999
8. Home Office Police Equipment Database, ped-cast.homeoffice.gov.uk
9. NIJ, Body Armor Performance Standards and Compliance Testing, nij.ojp.gov
10. SATRA, EN388:2016 Summary of Key Changes, 2016