Tape Mil Thickness Guide: What 1.6, 2.0, 2.6 and 3.1 Mil Mean and Which to Use
A mil is 0.001 inch, 25.4 microns, and on tape it is backing plus adhesive together. Carton sealing tape runs from 1.6 mil economy to 3.5 mil heavy duty; masking, filament, gummed and duct tapes sit at 5 to 11 mil and do a different job. This guide gives each band its microns, tape type, use and stocked products, and the adhesive and box weight tables that decide which one to buy.
What mil means on a roll of tape
A mil is one thousandth of an inch, 25.4 microns. On packing tape it is the total thickness of the film backing and the adhesive layer together, measured under ASTM D3652, so a 2.0 mil tape might be 1.4 mil of polypropylene film carrying 0.6 mil of adhesive. The number is a proxy for strength: thicker backing resists splitting and stretching, and more adhesive holds a rougher surface. It is not the whole story, because the adhesive type decides whether the tape holds at all on a recycled box or in a cold warehouse, and a 1.9 mil hot melt often outperforms a 2.2 mil acrylic on dusty kraft board. The chart pairs each thickness band with its tape type and use, with the number of stocked products in each band.
| Thickness | Microns | Tape type | Use | Stocked | Examples |
|---|---|---|---|---|---|
| 1.6 mil | 40.6 | Economy carton sealing (hot melt or acrylic) | Single wall boxes under about 30 lb, short transit, one-strip closure | 17 products | 2" x 55 yds Clear Carton Sealing Tape, 1.6 Mil, 2" x 55 yds Tan Carton Sealing Tape, 1.6 Mil |
| 1.8 to 1.9 mil | 45.7 to 48.3 | Standard carton sealing (hot melt or acrylic) | Everyday parcel sealing on 32 ECT boxes to about 40 lb | 38 products | 2" x 55 yds Clear Acrylic Carton Sealing Tape, 1.8 Mil, 2" x 55 yds Clear Hot Melt Carton Sealing Tape - 1.9 Mil |
| 2.0 to 2.2 mil | 50.8 to 55.9 | Standard acrylic carton sealing; most colored and printed tapes | General purpose to about 50 lb; acrylic holds in heat and cold and does not yellow | 144 products | 2" x 55 yds Clear Acrylic Industrial Tape, 2.0 Mil, 2 in x 55 yd Packing Tape - Green Carton Sealing 2 Mil |
| 2.5 to 2.6 mil | 63.5 to 66.0 | Industrial hot melt or acrylic | Heavy single wall and light double wall to about 65 lb; recycled-content boxes with dusty surfaces | 51 products | 3" x 55 yds Tan Industrial Carton Sealing Tape, 2.6 Mil, 2" x 55 yds Clear Acrylic Carton Sealing Tape, 2.6 Mil |
| 3.0 to 3.1 mil | 76.2 to 78.7 | Heavy duty carton sealing, quiet-release acrylic | Double wall boxes, overseas freight, storage over a year, boxes that are reopened | 9 products | 2" x 55 yds. 3.1 Mil, 2" x 55 yds. 3.1 Mil |
| 3.5 mil | 88.9 | Extra heavy duty carton sealing | Double and triple wall, export crating, high-value goods | 9 products | 3" x 55 yds Tan Acrylic Carton Sealing Tape, 3.5 Mil, 2" x 55 yds Tan Acrylic Carton Sealing Tape, 3.5 Mil |
| 4.9 to 5.2 mil | 124 to 132 | General purpose masking tape | Paint lines, bundling, labeling; not a closure tape | 107 products | 1/2" x 60 yds Masking Tape 4.9 Mil, 3/4" x 60 yds Masking Tape 4.9 Mil |
| 5 to 7 mil | 127 to 178 | Water-activated (gummed) kraft tape, reinforced | Tamper-evident carton closure that bonds to the fiber; the standard for fulfillment centers | 12 products | 72mm x 375' White Reinforced Water Activated Tape - 5.8, 72mm x 375' White Reinforced Water Activated Tape 6.4 Mil |
| 4 to 8 mil | 102 to 203 | Filament and strapping tape | Bundling, reinforcing box edges, palletizing; tensile strength 100 to 300 lb per inch | 24 products | 1/2" x 60 yds Poly Strapping Tape (12 Pack) - Industrial, 1/2" x 60 yds Filament Tape 897 - 6.0 Mil |
| 6 to 7 mil | 152 to 178 | Vinyl safety, floor marking and electrical tape | Aisle marking, color coding, insulation; not a carton tape | 107 products | 1" x 36 yds Yellow Vinyl Safety Tape, 6.0 Mil, 1" x 36 yds Red Vinyl Safety Tape, 6.0 Mil |
| 7 to 11 mil | 178 to 279 | Duct tape and cloth tape | Repairs, bundling, sealing plastic sheeting; cloth backing tears by hand | 55 products | 2" x 60 Yd Silver 9 Mil, 2" x 60 yds Black 10 Mil |
Two things the table makes plain. First, carton sealing tape lives in a narrow band, 1.6 to 3.5 mil; everything thicker is a different product that happens to be called tape. Second, the 2.0 mil class is where most of the stocked carton tape sits because it is the price-to-strength point for 32 ECT boxes, which are most boxes. The mil to micron conversion chart covers the same unit for poly bags, sheeting and film.
Adhesive matters as much as thickness
| Adhesive | Tack | Holds on | Temperature range | Ageing | Pick it for |
|---|---|---|---|---|---|
| Hot melt (synthetic rubber) | Highest initial tack; grabs recycled board | Kraft and recycled corrugated, dusty surfaces | About 40 to 120 F | Softens in heat, can ooze and yellow over months | Fast-paced packing lines, recycled-content boxes, shipments delivered in weeks |
| Acrylic | Moderate; builds over 24 hours | Clean kraft and white boxes | About 0 to 150 F | UV stable, does not yellow; the storage tape | Cold-chain, long storage, hot warehouses, printed boxes where clarity matters |
| Natural rubber | High tack, aggressive | Difficult surfaces, overfilled boxes, heavy board | About 20 to 150 F | Good; more expensive per roll | Heavy double wall, export freight, boxes under strain |
| Water-activated starch (gummed paper) | Bonds into the fiber once wet | Any corrugated, including recycled and dusty | Wide; the bond is mechanical | Permanent, tamper-evident | Fulfillment, ecommerce branding, any box that must show tampering |
The common failure is not a torn tape but a tape that lifts: hot melt applied in a 30 F trailer, acrylic applied to a dusty recycled box without pressure, or either one laid over a seam where the flaps do not meet flat. Rub the tape down after applying it; acrylic in particular needs pressure and an hour to reach its working bond. The carton vs kraft tape page covers the case for water-activated tape.
Which thickness for which box
| Packed box weight | Board | Tape thickness | Closure |
|---|---|---|---|
| Under 30 lb | 32 ECT single wall | 1.6 to 1.9 mil | One strip over the center seam (the I seal) |
| 30 to 50 lb | 32 ECT single wall | 2.0 to 2.2 mil acrylic or 1.9 mil hot melt | Center seam plus both edge seams (the H seal) |
| 50 to 65 lb | 44 ECT single wall or 48 ECT double wall | 2.5 to 2.6 mil | H seal; 3 inch tape on boxes over 18 inches wide |
| 65 to 120 lb | 48 to 51 ECT double wall | 3.0 to 3.5 mil, or 5 to 7 mil reinforced gummed | H seal top and bottom, or strapping over tape |
| Over 120 lb or palletized | Double or triple wall | Reinforced gummed tape or filament tape | H seal plus filament bands; box strength matters more than tape |
Width follows the box. 2 inch tape covers boxes to about 18 inches across the seam; 3 inch tape is for wider boxes, double wall, and any box where the flaps do not meet flat. The tape per box table works out rolls per thousand boxes for both widths.
Reading a tape spec sheet
- Thickness (mil): backing plus adhesive, as above. Some sheets list the backing alone; a 1.6 mil total tape may show a 1.0 mil film.
- Tensile strength (lb/in): force to break a 1 inch wide strip. Carton tape runs 20 to 35 lb/in; filament tape 100 to 300.
- Elongation (percent): how far it stretches before breaking. 100 to 150 percent for polypropylene carton tape; low elongation (under 5 percent) for filament tape, which is why filament does not creep under load.
- Adhesion to steel (oz/in): the standard peel test. 25 to 45 oz/in for carton tape; higher is tackier, not necessarily better on corrugated.
- Service temperature: the range the bond holds, not the range it can be applied in. Apply above 50 F for hot melt and acrylic whatever the service range says.
Quoted ranges are the conventional values from carton tape manufacturers' data sheets (Scotch 371 and 375, Intertape and Shurtape carton tapes); a specific product's sheet governs.
Shop carton sealing tapeKraft tapeMasking tape
Frequently asked questions
Is 2 mil tape strong enough for shipping?
For single wall boxes under about 50 lb, yes; 2.0 to 2.2 mil acrylic is the most common carton sealing tape. Go to 2.5 mil or heavier for double wall boxes or packed weights over 50 lb.
What is the difference between 1.6 mil and 2.0 mil tape?
Thickness: 1.6 mil is 40.6 microns and 2.0 mil is 50.8, a quarter thicker. 1.6 mil is economy tape for light boxes and short transit; 2.0 mil is the general purpose grade that holds to about 50 lb.
What mil is heavy duty packing tape?
2.5 to 3.5 mil for film carton sealing tape. Above that, heavy duty means a different construction: 5 to 7 mil reinforced water-activated kraft tape or 4 to 8 mil filament tape.
Does thicker tape stick better?
Not by itself. Adhesion comes from the adhesive type and how the tape is applied; thickness adds tear and stretch resistance. A 1.9 mil hot melt tape often holds a recycled box better than a 2.2 mil acrylic.
How many microns is 2 mil tape?
50.8 microns. Multiply mil by 25.4: 1.6 mil is 40.6 microns, 2.6 mil is 66 and 3.1 mil is 78.7.