Paper Shredder Security Levels Explained: The Complete DIN 66399 Guide
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DIN 66399 defines seven security levels for paper, written P-1 through P-7, and each one is defined by a maximum particle surface area: 2,000 mm² at P-1 down to 5 mm² at P-7. P-7 is the highest paper level the standard defines, and there is no P-8.
That single paragraph resolves most of the confusion in this category. The rest of this guide gives you the exact figures, the reasoning behind them, the five other media classes the standard covers, and the one relationship that is most often misstated in the shredder market: the difference between a DIN security level and an NSA/CSS listing.
The short version
- DIN 66399 is a German standard, now mirrored internationally as ISO/IEC 21964, that specifies how thoroughly a data carrier must be destroyed.
- It covers six media classes. Paper is class P. The others are F (film), O (optical), T (magnetic tape and cards), H (hard drives) and E (electronic media).
- Every class has seven levels, numbered 1 to 7. Higher numbers mean smaller particles.
- A level is a measured output specification, not a certification a vendor awards itself. A machine either produces particles within the maximum area for that level or it does not.
- NSA/CSS Specification 02-01 is a separate US government requirement. Meeting P-7 does not automatically mean a machine is on the NSA Evaluated Products List.
What DIN 66399 actually is
DIN 66399 was published by DIN, the German Institute for Standardization, to replace an older and much less granular shredding standard. It was written for a world in which sensitive information no longer lives only on paper, so it treats a hard drive, a microfiche and a printed contract as different problems requiring different destruction outcomes.
The standard is published in parts covering principles and definitions, requirements for machines, and the process of destruction. The international equivalent, ISO/IEC 21964 (Information technology — Destruction of data carriers), carries the same structure and the same level numbering, which is why you will occasionally see a machine described as meeting “ISO/IEC 21964 P-5” rather than “DIN 66399 P-5”. In practice these mean the same thing.
The three protection classes
Before choosing a level, the standard asks you to classify the information itself into one of three protection classes:
- Protection class 1 — normal protection requirement. Internal data whose disclosure would have a limited effect on the organisation or on individuals.
- Protection class 2 — high protection requirement. Confidential data, including personal data, where disclosure would have a substantial effect.
- Protection class 3 — very high protection requirement. Particularly confidential and secret data where disclosure could threaten the existence of the organisation or the safety of individuals.
The protection class narrows the sensible range of security levels; it does not pick one for you. Protection class 2, for example, is usually satisfied somewhere between P-4 and P-5 depending on how the material is handled before it reaches the machine.
The six media classes
| Class | Covers |
|---|---|
| P | Information in original size: paper, film, printing plates |
| F | Information in reduced form: microfilm, microfiche, foil |
| O | Optical data carriers: CDs, DVDs, Blu-ray discs |
| T | Magnetic data carriers: magnetic-stripe cards, ID cards, floppy disks, tape |
| H | Hard drives with a magnetic data carrier |
| E | Electronic data carriers: memory sticks, chip cards, solid-state media |
The seven paper security levels: the complete table
This is the table the rest of the market gets wrong. Every figure below is a maximum. A machine rated P-5 must produce particles no larger than 30 mm²; it may well produce smaller ones.
| Level | Max particle area | Max strip width | Typical cut type | Appropriate for |
|---|---|---|---|---|
| P-1 | 2,000 mm² | 12 mm | Strip-cut | General printed material with no confidentiality value: catalogues, brochures, superseded price lists, internal notices |
| P-2 | 800 mm² | 6 mm | Strip-cut | Internal documents: work instructions, routine forms, internal correspondence with no personal data |
| P-3 | 320 mm² | 2 mm | Cross-cut | Sensitive and confidential business data, and low-risk personal data |
| P-4 | 160 mm² | 6 mm | Cross-cut | Particularly sensitive personal data: HR files, contracts, payroll, patient and customer records. The practical baseline for most regulated offices |
| P-5 | 30 mm² | 2 mm | Micro-cut | Information intended to be kept secret: medical reports, strategy documents, financial models, legal privilege material |
| P-6 | 10 mm² | 1 mm | Micro-cut | Secret material with a high protection requirement: research and development, pre-announcement intellectual property, sensitive government work |
| P-7 | 5 mm² | 1 mm | Micro-cut | Strictly confidential material at the highest protection requirement: classified national security, military and intelligence documents |
Two sanity checks that are worth internalising. First, the jump from P-4 to P-5 is the single biggest step in the whole scale — particle area falls by more than five times. Second, P-6 to P-7 is a comparatively small step in area (10 mm² to 5 mm²) but a very large step in machine cost, throughput and maintenance burden.
Level by level, in plain terms
P-1 (max 2,000 mm²)
Wide strips, roughly 12 mm across. A determined person with time and a flat surface can reassemble P-1 output. Treat it as a tidiness measure rather than a security measure. It is legitimate for material you would be comfortable leaving on a desk.
P-2 (max 800 mm²)
Narrower strips at 6 mm. Still reconstructable with effort. Appropriate only where the consequence of disclosure is genuinely low.
P-3 (max 320 mm²)
The first level where the output is a particle rather than a strip, and the first that most people would recognise as real shredding. Reconstruction requires meaningful effort and specialist tooling. P-3 is a reasonable floor for general business confidentiality, though it is thinner cover than most regulated organisations want for personal data. Browse cross-cut shredders for machines in this range.
P-4 (max 160 mm²)
The workhorse of the regulated office. A P-4 particle is small enough that reconstruction is not a practical proposition for an opportunist, and the machines are fast, quiet and affordable enough for shared departmental use. If you handle HR records, patient information, financial account data or contracts and you are choosing a default, this is normally where the conversation starts. See P-4 shredders.
P-5 (max 30 mm²)
The first true micro-cut level. Output looks like coarse confetti. This is the level chosen by organisations that want defensible headroom above the regulatory minimum without moving into high-security machinery — hospitals, law firms, financial services and anyone whose risk assessment concludes that P-4 is adequate but uncomfortably close to the line. See P-5 shredders.
P-6 (max 10 mm²)
High-security territory. Throughput per pass drops sharply, sheet capacity falls, and the machines need serious motors and disciplined maintenance. Chosen where the material would cause severe harm if recovered, and in defence and government environments that have not been told specifically to use an NSA-listed machine. See P-6 shredders.
P-7 (max 5 mm²)
The highest paper level in the standard. Particles are roughly 1 mm by 5 mm. These are purpose-built machines with low sheet capacity relative to their size, substantial waste volume, and a real maintenance regime. They exist for classified national security information and equivalent material. See P-7 shredders and the wider high security shredder range.
There is no P-8
You will find shredders advertised as “Level 8”, and you will find category pages built around the idea. It is not a thing. DIN 66399 numbers its levels 1 to 7 for every one of its six media classes. P-7 is the maximum for paper. There is no eighth level to reach, and no standards body issues one.
Where does the claim come from? Usually one of three places:
- Confusion with the old standard. The predecessor to DIN 66399 used a different scale that topped out at level 6. When the market moved to the new scale, some catalogues renumbered by adding one, producing a phantom “level 7” and then a phantom “level 8”.
- Confusion with NSA/CSS. Machines that meet NSA/CSS Specification 02-01 are sometimes described as being “beyond P-7”. They are not beyond it; 02-01 and P-7 are close to the same particle target, arrived at by different routes.
- Marketing. A bigger number reads as a better machine.
If a supplier cannot tell you the maximum particle area in mm², the level claim is decoration. Ask for the number.
Cut types and what they actually tell you
Cut type describes the geometry of the cutting head. It correlates with security level but does not define it — the level is defined by measured particle area.
- Strip-cut shredders slice paper into long parallel ribbons. They map to P-1 and P-2. They are fast, tolerate large stacks and rarely jam, which is why they persist in high-volume, low-sensitivity settings.
- Cross-cut shredders cut in two directions, producing rectangular particles. They cover P-3 and P-4.
- Micro-cut shredders use finer cutting geometry to produce very small particles, covering P-5, P-6 and P-7. They run slower, hold fewer sheets per pass, fill bins faster because the material does not compact the same way, and need more consistent lubrication.
Note the overlap at P-4: some manufacturers market P-4 machines as “micro-cut” because the particles are visibly small. The honest test remains the measured area.
DIN 66399 and NSA/CSS 02-01 are not the same thing
This is the most consequential distinction in the whole category, and the one most often blurred.
DIN 66399 is a European output specification. Any manufacturer can build to it and state the level.
NSA/CSS Specification 02-01 is a United States National Security Agency requirement for high-security crosscut paper shredders used on classified national security information. The NSA/CSS Evaluated Products List for high security crosscut paper shredders states that approved machines must reduce paper to shards of five millimetres square or less in area, and notes that one millimetre by five millimetres is the most common resulting particle size. NIST Special Publication 800-88 Rev. 1 uses the same figure, directing organisations to “destroy paper using cross cut shredders which produce particles that are 1 mm x 5 mm (0.04 in. x 0.2 in.) in size (or smaller), or pulverize/disintegrate paper materials using disintegrator devices equipped with a 3/32 in. (2.4 mm) security screen.”
So the particle targets are essentially the same. The difference is the process:
- A DIN level is a claim about output that the manufacturer makes and that can be measured.
- An NSA/CSS listing means a specific make and model has been evaluated by the NSA and appears by name on the Evaluated Products List.
A machine can be P-7 and not be on the Evaluated Products List. If your requirement is to destroy classified material, P-7 is not sufficient evidence of compliance; the model must be named on the current EPL, which the NSA publishes at nsa.gov. Always check the list itself rather than a vendor's summary of it, and confirm the exact model and revision. Our government shredder range is a starting point, but the EPL is the authority.
The other media classes
If you are disposing of anything other than paper, the P scale does not apply. Here are the maximum particle areas for the other five classes.
Class F — film and microform
| Level | Max particle area |
|---|---|
| F-1 | 160 mm² |
| F-2 | 30 mm² |
| F-3 | 10 mm² |
| F-4 | 2.5 mm² |
| F-5 | 1.0 mm² |
| F-6 | 0.5 mm² |
| F-7 | 0.2 mm² |
The figures are far tighter than the paper equivalents for an obvious reason: microform stores the same content at a fraction of the size, so a fragment of the same physical area carries far more recoverable information.
Class O — optical media
| Level | Max particle area |
|---|---|
| O-1 | 2,000 mm² |
| O-2 | 800 mm² |
| O-3 | 160 mm² |
| O-4 | 30 mm² |
| O-5 | 10 mm² |
| O-6 | 5 mm² |
| O-7 | 0.2 mm² |
Snapping a disc in half is not O-anything. A standard office shredder with a CD slot typically lands around O-2 or O-3, which is appropriate for routine material and not for confidential data.
Class T — magnetic data carriers
| Level | Requirement |
|---|---|
| T-1 | Rendered mechanically inoperable |
| T-2 | Max 2,000 mm² |
| T-3 | Max 320 mm² |
| T-4 | Max 160 mm² |
| T-5 | Max 30 mm² |
| T-6 | Max 10 mm² |
| T-7 | Max 2.5 mm² |
Class H — hard drives
| Level | Requirement |
|---|---|
| H-1 | Rendered mechanically or electronically inoperable |
| H-2 | Medium rendered unusable by damaging or degaussing it |
| H-3 | Medium deformed |
| H-4 | Deformed and disintegrated, max 2,000 mm² |
| H-5 | Max 320 mm² |
| H-6 | Max 10 mm² |
| H-7 | Max 5 mm², or heated above the Curie temperature |
Note that H-1 to H-3 are not particle specifications at all. They describe states. This matters: a bent drive satisfies H-3 but a laboratory can still read platters, which is why anything genuinely sensitive belongs at H-5 or above, or should be degaussed first and then destroyed. Digital media shredders cover this ground.
Class E — electronic data carriers
| Level | Requirement |
|---|---|
| E-1 | Rendered mechanically or electronically inoperable |
| E-2 | Disintegrated |
| E-3 | Max 160 mm² |
| E-4 | Max 30 mm² |
| E-5 | Max 10 mm² |
| E-6 | Max 1 mm² |
| E-7 | Max 0.5 mm² |
Solid-state media is the hardest case in the standard. A single surviving flash chip can hold a great deal of data, so the E levels tighten far faster than the paper levels do. Degaussing does nothing to solid-state media.
How to choose a level without over-buying
- Classify the material first, not the machine. Work out which protection class your worst-case document falls into. Buy for that document, not the average one.
- Check whether a regulator or contract has already decided. Government work, defence subcontracts and some client agreements specify a level or an NSA listing outright. If so, the decision is made.
- Match throughput honestly. A high-security machine that people avoid because it is slow produces a bin of unshredded paper next to it. That is a worse outcome than a P-4 machine that gets used.
- Cost the consumables. Higher levels fill bags faster and need more lubrication. Budget for oil and bags, not just the machine.
- Write the level into your policy. A documented decision that says “personal data is destroyed at DIN 66399 P-5 or better” is far more defensible in an audit than a machine that happens to be adequate.
Frequently Asked Questions
Is there a P-8 security level?
No. DIN 66399 defines seven levels for each media class. P-7 is the highest defined level for paper, with a maximum particle area of 5 mm². Any product advertised as “Level 8” is using a label that does not exist in the standard, usually because of a renumbering error carried over from the older standard or because a machine meets NSA/CSS 02-01 and the seller wants to signal something above P-7.
Does a P-7 shredder meet NSA requirements automatically?
No. NSA/CSS Specification 02-01 is satisfied only by specific makes and models that the NSA has evaluated and published on its Evaluated Products List. A machine can produce P-7 particles and not appear on that list. If you are destroying classified national security information, verify the exact model against the current EPL on nsa.gov before purchase.
What security level do I need for personal data such as HR or patient records?
Most organisations land on P-4 as a baseline and P-5 where they want headroom. Neither figure comes from a statute — regulations such as HIPAA and the FTC Disposal Rule require that information cannot practicably be read or reconstructed, and do not name a DIN level. P-4 and P-5 are the levels at which that outcome is straightforward to defend.
What is the difference between cross-cut and micro-cut?
They are descriptions of cutting geometry, not formal grades. In practice cross-cut machines occupy P-3 and P-4, and micro-cut machines occupy P-5 through P-7. Because the terms are not standardised, treat the stated DIN level and maximum particle area as the specification and the cut-type label as shorthand.
Does DIN 66399 apply outside Germany?
It is used worldwide as the de facto commercial specification for destruction equipment, and it has been adopted internationally as ISO/IEC 21964, Information technology — Destruction of data carriers. US regulators do not require a DIN level, but US buyers use the scale because it is the only widely available way to compare machines objectively.
How can I verify a manufacturer's security level claim?
Ask for the maximum particle dimensions in millimetres, multiply them, and compare against the table above. A machine advertised as P-5 that produces a 4 mm by 12 mm particle has an area of 48 mm² and is therefore P-4, not P-5. Reputable manufacturers publish the particle dimensions in the technical specification; if the figure is missing, that absence is informative.
Figures in this guide are taken from DIN 66399 / ISO/IEC 21964 as published by shredder manufacturers and industry bodies, the NSA/CSS Evaluated Products List for High Security Crosscut Paper Shredders, and NIST Special Publication 800-88 Rev. 1. Where sources differ we have said so rather than picked a number.