Shredder Specifications Explained
Shredder datasheets reuse a small set of numbers, and most are less obvious than they look. This page explains what each specification measures, where the published figure is optimistic, and how to use it when choosing a machine. For side-by-side machines instead of definitions, use the comparison page.
Security level (DIN 66399)
DIN 66399 is the European standard that replaced DIN 32757 in 2012. For paper it defines seven security levels, P-1 to P-7. Each level is set by a maximum particle surface area — an upper limit on how large a single fragment may be — and, at the tighter levels, by a maximum particle width as well. It is a geometric specification. It says nothing about motor quality, build, or how long the machine will last.
| Level | Max particle area | Typical cut | What it is genuinely for | Browse |
|---|---|---|---|---|
| P-1 | ≤ 2,000 mm² | Strip-cut, strips up to 12 mm wide | General waste paper reduction. Not a confidentiality control. | P-1 |
| P-2 | ≤ 800 mm² | Strip-cut, strips up to 6 mm wide | Internal, non-sensitive documents. Also not a confidentiality control. | P-2 |
| P-3 | ≤ 320 mm² | Cross-cut | The entry point for confidential material. Adequate for routine internal paperwork. | P-3 |
| P-4 | ≤ 160 mm² | Cross-cut | The commercial default. Personal data, HR files, customer records, finance. | P-4 |
| P-5 | ≤ 30 mm² | Micro-cut | Regulated sectors: healthcare, legal, financial services, R&D. | P-5 |
| P-6 | ≤ 10 mm² | Micro-cut | Secret and highly sensitive material. | P-6 |
| P-7 | ≤ 5 mm² | Micro-cut | Classified and top-secret material. | P-7 |
Three things are worth being blunt about.
The scale stops at P-7. There is no P-8 in DIN 66399, and there never has been. If a listing anywhere advertises a P-8 shredder, the rating is invented.
P-1 and P-2 are not confidentiality controls. They are strip-cut ratings. A P-2 strip is up to 6 mm wide and runs the full length of the page, so a determined person with time can reassemble it. Buy P-1 or P-2 for volume waste reduction, not for anything you would mind seeing reconstructed. Confidentiality starts at P-3 and, in practice, at P-4.
DIN P-7 is not the same as NSA/CSS approval. NSA/CSS Specification 02-01 requires a particle of 1 mm x 5 mm and that the specific model is listed on the NSA Evaluated Products List. A machine can satisfy DIN P-7 with a 0.8 x 4.5 mm cut and still not appear on the EPL. For federal work, check the list for the exact model — see Government & NSA/CSS Approved Shredders and the guide to CUI and government document destruction.
DIN 66399 also covers other media, with separate scales: O for optical discs, T for magnetic tape, H for hard drives and E for electronic media such as USB sticks and SSDs. Machines rated for those are in Digital Media Shredders. The full treatment of the standard is in our DIN 66399 security levels guide.
Cut type and cut size
Cut type is a description; cut size is the measurement that determines the security level.
- Strip-cut slices the page into long parallel ribbons. Fast, high sheet capacity, low security. Corresponds to P-1 and P-2. See Strip-Cut Shredders.
- Cross-cut (also called particle cut) uses two opposed cutting shafts to cut across the strips as well as along them, producing rectangular confetti. Corresponds to P-3 and P-4. See Cross-Cut Shredders.
- Micro-cut is the same mechanism with a much finer cutting head, producing particles small enough for P-5, P-6 and P-7. See Micro-Cut Shredders.
Cut size is quoted as width x length: 3.9 mm for a strip-cut, 4 x 40 mm for a typical P-4, 1.9 x 15 mm for P-5, 0.8 x 4.5 mm for P-7. Multiply the two and you have the particle area that determines the level — worth doing yourself when a listing quotes a level but not a size, or the reverse.
Sheet capacity and the paper-weight caveat
Sheet capacity is the number of sheets the machine will take in one pass. It is the most quoted specification and the most misleading, because the published figure assumes ideal conditions: 20 lb bond / 80 gsm paper, a single flat stack, a cold machine and full rated voltage.
Real offices depart from that in every direction. Heavier stock reduces capacity roughly in proportion to weight — 24 lb paper can cost two or three sheets against the rating. Folded sheets count double. Staples are tolerated by most commercial machines but blunt the cutting head over time. A motor running for twenty minutes takes fewer sheets than a cold one.
The practical rule is to size the machine at about 70% of its published capacity for sustained work. If your users routinely feed 15 sheets, buy a machine rated for 20 or more rather than one rated for 15. Feeding at or above the rating is the single most common cause of jams — see shredder troubleshooting.
Auto-feed machines quote two numbers: a tray capacity (150, 300, 600 sheets) and a manual-slot capacity, which is much lower. The tray figure is the one that describes unattended throughput; the manual figure is what you get when you feed by hand. Both matter. See Autofeed Shredders.
Throat width
Throat width is the usable width of the feed opening, and it is a hard limit rather than a soft one. US Letter is 8.5 in wide, so any machine with a throat of 9 in or more takes Letter comfortably. A 12 in throat takes Legal and Tabloid landscape. Wider throats — 16 in and above on large-office and industrial machines — exist to take computer printout, folded plans and continuous stationery without pre-cutting.
Check throat width against the widest document you actually shred, not the most common one. Nothing kills a shred routine faster than folding every wide sheet before it goes in.
Bin volume
Bin volume, quoted in gallons or litres, decides how often the bin gets emptied. It interacts with security level in a way that catches people out: a higher security level produces more particles per sheet, and shredded paper at P-5 or P-6 packs less densely than at P-4. Two machines with identical 38-gallon bins will need emptying at very different intervals if one is P-4 and the other P-6.
Emptying frequency is a real operating cost. Sizing up one bin tier is usually cheaper than the labour. Consumables are in Shredder Bags and Shredder Bins & Carts.
Duty cycle
Duty cycle is how long the machine can run before it must rest, usually written as run time / cool-down time — for example 30/30, meaning thirty minutes on and thirty minutes off. It is the specification that separates a machine that survives office use from one that does not.
Read the wording carefully. Continuous duty means the motor is rated to run indefinitely at load. Continuous operation and extended run time are marketing phrases and usually mean neither. Small-office machines commonly quote something like 10/30; departmental machines 60/15 or better; industrial machines are genuinely continuous. Exceeding the duty cycle trips the thermal cut-out, which is a protection rather than a fault, but repeated over-running shortens motor life. There is a full treatment in how to choose an industrial shredder for continuous duty.
Noise level
Noise is quoted in decibels (dB), measured at a set distance while shredding — idle figures are lower and less useful. Around 55 dB is quiet enough for an occupied office; 60 to 65 dB is normal for a departmental machine and noticeable in open-plan; above 70 dB the machine wants its own space. The scale is logarithmic, so 10 dB more is roughly twice as loud. If the shredder sits next to desks, this matters more than buyers expect.
Motor rating
Motor power is quoted in watts or horsepower, and it correlates with sustained throughput rather than peak capability. It is only meaningful alongside duty cycle and voltage: a 1,000 W motor on a 10/30 duty cycle is a different proposition from a 1,000 W motor rated continuous.
Check the electrical supply too. Most office machines are single-phase 120 V. Large departmental and industrial machines are frequently 220 V single-phase or 208/230 V three-phase, which means an electrician and a dedicated circuit before the machine can be commissioned. That cost belongs in the purchase decision, not after it.
Putting it together
A workable order for the decision: fix the security level from your compliance obligation first, because it constrains everything else. Then set sheet capacity and duty cycle from your daily volume and the number of users. Then check throat width against your widest document, and bin volume against how often you are willing to empty it. Noise and motor rating are the tie-breakers between two machines that already fit.
If a compliance rule is driving the purchase, start with what shred size HIPAA requires or the FACTA disposal rule. To see these specifications applied to real machines, go to the comparison page, or browse all shredders. Whatever you buy, it will last longer if you oil it properly.