What Is a Gusseted Bag? Uses, Sizes and How to Measure One
A gusseted bag is a poly bag with extra film folded into its sides or bottom, so it opens into a square base instead of lying flat. The fold is called a gusset, and it lets the bag hold box-shaped goods, line a carton or gaylord box, or cover a machine without being stretched tight.
Tuosheng Packaging makes gusseted poly bags to size in Suzhou, China, in LDPE and HDPE. This guide explains what the gusset does, the four main industrial uses, how to size a gaylord liner and how to read W × G × L on a quote. If you are new to bag types, start with our guide to what a poly bag is.
Quick answer
- A gusseted bag is a poly bag with film folded into its sides or bottom, so it opens into a square base.
- A gusseted bag is sized width × gusset × length (W × G × L), all measured inside the bag.
- Side-gusset bags are the type used for industrial packing, because they open into a box shape that fits cartons, bins and machines.
- The four main industrial uses of gusseted bags are packing box-shaped parts, lining cartons, lining gaylord boxes and covering machinery.
- Before you order, agree with the supplier whether the gusset figure means the full opened width or one folded side; the two differ by half.
What Is a Gusset on a Bag?
A gusset on a bag is a section of film folded into the side or bottom of the bag that opens out when the bag is filled. The gusset gives the bag depth, so a gusseted bag holds a square or bulky item that would stretch a flat bag tight.
A flat bag has two faces and no depth. A gusseted bag has two faces plus two folded side panels, and when the bag opens, those panels form the ends of a rectangular base.
What is a gusset?
A gusset is a folded panel of film in the side or bottom of a bag that expands to give the bag depth.
What is a side gusset bag?
A side gusset bag has a gusset folded into each side and a sealed bottom, so the bag opens into a square base and box shape.
What is a bottom gusset bag?
A bottom gusset bag has a gusset folded into the base, so the bottom spreads out and the bag can stand up when filled.
What is a square bottom bag?
A square bottom bag is another name for a side gusset bag, because its folded sides open into a flat, square bottom.
Suppliers use these names loosely, so “gusseted bag”, “square bottom bag” and “bottom gusset bag” can mean the same bag or different ones. Send a photo or drawing with your enquiry, or write “side gussets, flat sealed bottom” on the order.
What Is the Difference Between a Side Gusset and a Bottom Gusset Bag?
A side gusset bag has a fold in each side and opens into a box shape, which suits square goods and liners. A bottom gusset bag has a fold in the base and stands up when filled, which suits retail and food packs more than industrial packing.
| Bag type | How it is made | Typical use | What it means for an industrial buyer |
|---|---|---|---|
| Flat bag | Two faces, sealed bottom, no gusset | Flat or thin items | Cheapest and simplest; stretches tight around box shapes |
| Side gusset bag | A fold in each side, sealed bottom | Box-shaped parts, carton and gaylord liners, machine covers | Opens into a square base that fits the goods or the box |
| Bottom gusset bag | A fold in the base | Stand-up retail and food packs | Rarely the right choice for parts or liners |
| Gusseted poly tubing | A side-gusset tube on a roll, no seals | Packing lines that cut and seal their own bags | One roll covers many bag lengths |
This guide covers side gusset bags, the type used for industrial packing. If your goods are flat, flat poly bags cost less. If you cut and seal bags on your own line, gusseted poly tubing on a roll lets you choose the length for each job.
What Are Gusseted Bags Used For?
Gusseted bags have four main industrial uses: packing box-shaped parts, lining cartons, lining gaylord boxes and bins, and covering machinery. In each case the goods or the container are square, and a flat bag either won’t fit or gets stretched until it splits.
| Use | Typical bag | What the bag does | What to send the supplier |
|---|---|---|---|
| Box-shaped parts and bulky goods | Small to medium, about 2 mil (0.05 mm) | Packs automotive parts, components and boxed products against dust | Product size and weight |
| Carton and box liners | Sized to the carton, about 2 mil; 1–1.5 mil for light, clean goods | Keeps dust and moisture off the goods inside a carton | Inside carton size |
| Gaylord and bin liners | Extra large, heavier film for heavy loads | Lines bulk boxes and bins, such as 48 × 40 in gaylords | Box length, width and depth |
| Machinery and equipment covers | Large, heavy gauge, up to 0.2 mm (about 8 mil) | Covers machines against dust and moisture in storage and transit | Machine footprint and height |
To cover a whole loaded pallet, use pallet covers, not a gusseted bag sized to each carton. Clear gusseted bags keep labels readable; black bags hide the goods.
What Is a Gaylord Liner, and What Size Do You Need?
A gaylord liner is a large gusseted poly bag placed inside a gaylord box or bulk bin to keep dust and moisture off the contents and stop loose material leaking through the corners. A gaylord liner is sized from the inside of the box, and many North American gaylords sit on the standard 48 × 40 in pallet footprint.
What is a gaylord box?
A gaylord box is a large corrugated bulk box, usually built on a pallet, used to ship or store loose parts, resin, scrap and other bulk goods.
A common rule of thumb for sizing a liner from the inside of the box:
Bag width = box length
Gusset (full opened width) = box width
Bag length = box depth + half the gusset + 12–16 in to fold over the rim
For a box that measures 48 × 40 × 36 in inside, that gives a bag width of 48 in, a gusset of 40 in and a bag length of about 36 + 20 + 12 to 16 = 68 to 72 in. The liner is written 48 × 40 × 72 in. Some buyers add an inch or two to the width and gusset so the liner drops into the box without pulling at the corners.
Heavy or sharp loads need heavier film, up to 0.2 mm (about 8 mil), and LDPE resists punctures better than HDPE at the same thickness. Our guide to plastic bag thickness covers the full range. If the gaylords travel on pallets, the same load rules apply as for any palletized freight; see pallet stacking patterns.
How Do You Measure a Gusseted Bag?
A gusseted bag is measured as width × gusset × length (W × G × L), all inside the bag. Width is the face of the bag across the opening, gusset is the depth the side folds add when fully opened, and length runs from the opening to the bottom seal.
| Figure | What it measures | How to check it on a sample |
|---|---|---|
| W (width) | The front face, across the opening, with the gussets folded in | Lay the bag flat and measure across |
| G (gusset) | The depth of the opened bag, from the front face to the back face | Open the bag into a box shape and measure the end panel |
| L (length) | From the opening to the bottom seal | Lay the bag flat and measure top to bottom |
The figure most often misread is G. G usually means the full opened width of the gusset, so a 48 × 40 × 72 in liner opens to a 48 × 40 in base. Some quotes instead give the depth of one folded side, which would be 20 in for the same bag. Tuosheng agrees the meaning of G with each customer before quoting and normally writes the full opened width.
The safest way to order is to send the inside size of the box, or the bag you use now, and let the factory work out the bag. Tuosheng confirms the size of gusseted poly bags and sends samples to check the fit before bulk production.
Should You Choose a Gusseted Bag, a Flat Bag or a Pallet Cover?
Choose a gusseted bag when the goods or the container are square, a flat bag when the goods are flat, and a pallet cover when you are covering a whole pallet load. The shape of what goes inside decides the bag, not the size alone.
| What you are packing | Choose | Why |
|---|---|---|
| Flat or thin items | Flat poly bag | Lowest film use; no depth needed |
| Box-shaped parts | Gusseted bag | Opens to the shape of the part instead of stretching around it |
| Cartons, bins and gaylord boxes | Gusseted liner | The square base sits flat in the box |
| A whole loaded pallet | Pallet cover | Sized to the pallet footprint and load height |
| Many sizes on one packing line | Gusseted poly tubing | Cut and seal each bag to length |
A flat bag big enough to take a box-shaped item has to be both wider and longer than a gusseted bag, and the extra film bunches at the corners. For square goods, a gusseted bag usually uses less film for a neater fit. Compare flat poly bags, poly tubing and pallet covers if you are unsure.
What Is a Gusseted Bag FAQ
Is a gusseted bag the same as a square bottom bag?
Usually, yes. A side gusset bag opens into a flat, square bottom, so suppliers also call it a square bottom bag. A bottom gusset bag is a different style that stands up, so confirm which one you mean with a photo or drawing.
What does W × G × L mean on a poly bag?
W × G × L means width × gusset × length, measured inside the bag. Width is the face across the opening, gusset is the opened depth of the side folds, and length runs from the opening to the bottom seal.
What size gaylord liner do I need for a 48 × 40 box?
For a gaylord box that is 48 × 40 in inside, the liner is usually 48 in wide with a 40 in gusset. Add the box depth, half the gusset and 12–16 in of fold-over to get the length, so a 36 in deep box takes a liner of about 48 × 40 × 72 in.
What thickness should a gaylord liner be?
A gaylord liner for light, clean goods can be about 2 mil (0.05 mm). Heavy, sharp or abrasive loads need heavier film, up to 0.2 mm (about 8 mil), and LDPE resists punctures better than HDPE at the same thickness.
Can gusseted bags be printed?
Yes. Gusseted bags can be printed with a logo, handling instructions or product codes. Tuosheng prints to your artwork and confirms the layout before production.
Get Gusseted Bags Made to Your Size
Tuosheng Packaging manufactures gusseted poly bags in Suzhou, China, in LDPE and HDPE, with 0.05 mm (about 2 mil) as standard and up to 0.2 mm for heavy goods. Gusseted bags are made to your width, gusset and length, including liners for 48 × 40 in gaylord boxes, in clear, black or custom colors, and can be printed or made with GRS-certified recycled PE. We also make gusseted poly tubing on a roll and other poly bags, and bags can ship in the same container as stretch film; see importing stretch film from China for mixed loads.
Send us the inside size of your box, the size of your goods or the bag you use now through the gusseted poly bags page. We will confirm the size, agree how the gusset is measured and send samples to check the fit.
Recommended Tuosheng Packaging Solution
Tuosheng Packaging manufactures poly bags, pallet covers and poly tubing in Suzhou, China, made to your size, thickness and printing, and shipped with stretch film in one container if you need both.
