Online Ordering is available 24/7
Updated: November 10, 2026
An evidence bag too small forces officers to break the seal and start the chain of custody over. One too big lets trace items shift inside and risks tampering going unnoticed. Choosing the right bag size for the items your department collects is what keeps every case court-ready.
This guide walks through size selection by item type across various sizes, when to use plastic evidence bags versus paper evidence bags, and the key features that make every sealed bag defensible at trial.
Every time a bag is reopened, the chain of custody record grows. Each entry adds a point where a defense attorney can question handling or claim tampering. A right-sized bag means one seal, one custody record, and clean packaging that holds up in court.
Undersizing damages evidence. Folding a firearm to fit, compressing fabric for trace analysis, or jamming a laptop into a bag built for a phone creates handling artifacts that complicate any investigation. Police officers know undersized packaging can destroy a case during forensic review and raise the risk of an inadmissibility ruling.
Oversizing creates the opposite problem. Excess space lets trace items disperse inside the bag, and contamination across crime scene items becomes a real risk during transport. Fingerprints, fibers, powders, and other trace evidence all shift when there is room to move, and shifting fingerprints on a recovered surface raise contamination risk further.
Accurate documentation on every bag, including case numbers, officer names, and scene details, is essential to maintaining evidence integrity. Preserving every recovered item starts with the right size, the right material, and clear labels on the panel.
Before choosing a size, choose a material. Plastic evidence bags and breathable paper bags serve different evidence types, and the wrong material destroys a case regardless of dimensions. The right material is the best container for the evidence type, and preserving evidence integrity depends on that choice.
Plastic evidence bags are the right packaging for most non-biological items. Plastic protects against outside moisture, shows tampering through the tamper evident seal, and accepts printed documents and labels without smudging. Use plastic bags for firearms (after clearing), narcotics, electronics, currency, and dry property recovered from a crime scene.
Most plastic evidence bags are polyethylene rated for the contents. Reinforced edges improve durability and reliability, protecting contents from accidental damage and from tampering during transit between the scene, the evidence room, and the courthouse where police departments store the bags long-term.
Paper bags breathe. That property makes breathable packaging the right choice for wet or biological items collected at a crime scene. Sealing wet items inside plastic promotes moisture buildup, mold growth, and degraded DNA within days.
Use breathable packaging for damp clothing, blood-soaked items, and biological samples that need to air-dry. Breathable bags accept the same printed labels and tamper evident closures that plastic does.
Most police departments stock three to five bag sizes that cover 90 percent of intake from any crime scene, plus a small reserve for biological samples and oversize property. The process of selecting the right bag starts with the item.
A handgun fits a 12×16 evidence bag. Long guns need dedicated 8×44 or 11×52 long-gun bags depending on barrel length. Heavy items require thicker plastic to prevent tearing under the weight during transport. Firearm collection carries additional security risk, so the packaging needs to maintain custody throughout transport.
Most narcotics intake fits 9×12 or 10×13 evidence bags. Bulk seizures from a trafficking investigation need 15×20 or larger bags, and large quantities should be double-bagged to deter tampering. Heat-sealed bags provide an extra layer of protection for high-security items, creating a permanent closure that cannot be reopened without visible damage. That closure makes heat-sealed bags the right packs for federal cases.
Biological samples must breathe. Use breathable bags or Tyvek pouches, not plastic. Standard sizes are 6×9 for swabs, blood, and fingerprint cards, 10×13 for fabric items, and 15×20 for larger items. Never seal wet biological evidence in plastic, even briefly, because moisture begins degrading DNA within hours.
Phones and tablets need anti-static or Faraday-lined evidence bags in 6×9 or 9×12. Laptops fit 12×16 or 15×20 bags with the screen face up. Larger electronics require 24×36 plastic bags. Faraday packs protect electronic evidence from remote wipe during the investigation.
Soft items like garments dry best one step larger than the item. Bulky property fits 24×36 evidence bags. Knives, broken glass, and other sharp objects go into puncture-resistant inner containers first, then into plastic bags sized to fit without slack. The inner container preserves the original condition of the evidence.
Tamper evident evidence bags feature a sealing mechanism that shows clear signs if the bag has been opened, preserving the integrity of every item recovered. That mechanism only works when bags are sized correctly. Seal integrity requires leaving 2 to 3 inches of space at the top for proper closure, so contents do not interfere with the adhesive strip and any tampering attempts remain clearly visible.
Measure 3D volume when choosing a bag. Account for item thickness, not just length and width. A wallet 1 inch thick takes more bag volume than a flat 6×9 footprint suggests, and crowding the bag can compromise the seal or mask later tampering.
Tamper proof construction matters as much as size. Reinforced edges and heat-sealed side seams protect against tearing and tampering during the weeks or months the bags spend in the evidence room. Heavy items require smaller, thicker tamper evident bags to prevent tearing rather than oversized bags in lighter material. Durability plays a vital role in keeping the packaging performing over time.
Tamper proof evidence bags include adhesive void-messaging seals, sequential numbering, side-seam patterns, and durable reinforced edges. Each works to maintain custody from the scene through storage to the courtroom.
A printed label is an essential tool on every evidence bag. The fields on the label, including the case number, officer names, and scene details, are essential to ensuring items are admissible in court and to maintaining the credibility of the evidence collected.
Police officers fill out labels in the field, often in difficult conditions. The label on every bag should be sized for legible completion, printed with the required field documents, and durable enough to survive handling. Smudged or torn labels create authenticity questions that defense attorneys exploit during legal proceedings.
Investigators and forensic teams rely on field labels to track every item collected through the investigation. A clearly labeled bag with complete entries lets an investigator trace evidence from the scene to the lab to the courtroom without breaking custody.
Environmental factors affect packaging over time. Temperature, humidity, and light all contribute to environmental damage on bags stored long-term. The right material and size together protect against degradation that compromises later forensic work and reduces the risk of admissibility challenges in court.
Item type | Recommended size | Material |
Handgun | 12×16 | Tamper evident |
Rifle or shotgun | 8×44 or 11×52 | Long-gun bag |
Narcotics, small qty | 9×12 or 10×13 | Heat-sealed |
Narcotics, bulk | 15×20+ | Double-bagged |
Phone, tablet | 6×9 or 9×12 | Faraday |
Laptop | 12×16 or 15×20 | Standard plastic |
Biological swab | 6×9 | Breathable |
Wet biological | 14×20 or 18×24 | Sized one up |
Fingerprint cards | 6×9 | Breathable |
Bulky property | 24×36+ | Reinforced |
Knives, broken glass | Sized to inner | Over puncture-proof |
Evidence room audits surface the same handful of mistakes across departments of every size. Recognizing the patterns is a key part of the procurement process.
Law enforcement agencies that maintain a consistent evidence packaging process see fewer chain of custody challenges. Best practices for an agency program include standardizing on a small set of sizes, training officers on the right pack for each item type, and auditing the evidence room annually to maintain inventory accuracy.
Crucial items like firearms, narcotics, and biological evidence deserve dedicated specialty packaging. The investment in proper plastic evidence bags pays back through reduced courtroom challenges and stronger conviction rates. Ensuring justice depends in part on the physical condition of every piece of evidence an officer collected at the scene.
A practical stock list covers high-volume bag sizes for everyday intake plus a reserve of specialty packs. For example, a mid-size department typically maintains the following inventory year over year:
Bag type | Stock quantity | Typical use |
6×9 plastic | 500 | Phones, ammo, ID cards |
9×12 plastic | 1000 | Narcotics, electronics |
12×16 plastic | 500 | Handguns, laptops |
15×20 plastic | 250 | Bulk narcotics, property |
24×36 plastic | 100 | Bulky property, tools |
14×20 paper | 250 | Wet biological |
8×44 long-gun bag | 50 | Rifles, shotguns |
Faraday 9×12 packs | 100 | Cell phones, GPS units |
Sizing is one part of a larger evidence handling process. It connects to how to label evidence bags, how police departments store the items long-term, and the chain of custody bag requirements every agency needs to meet for court admissibility. The importance of clear documentation cannot be overstated.
Our guide on evidence bag vs property bag covers the difference between case evidence and arrestee personal effects, another sizing decision that affects how agencies stock their evidence room and how investigators track items through the collecting evidence process.
Superior Bag manufactures evidence bags in every standard size plus long-gun, oversize, Faraday-lined, and heat-sealed tamper proof packs. Custom printing of department name, ORI number, sequential numbering, and any agency-specific labels is available across the line.
Browse the evidence bag catalog or contact us for a quote sized to your department’s intake and the right bags and packs for every item your officers collect.
Back to Blog