Mylar bag sizing trips people up because the number on the label describes the flat bag, not the space inside it. A 5 by 8 bag is a flat pouch measuring five inches across and eight inches tall before anything is put in it, and by the time you subtract the seals and leave room to close it, the usable interior is meaningfully smaller.
How the measurements are written
| Figure | What it describes |
|---|---|
| Width | Across the flat bag, edge to edge, seals included |
| Length | Bottom to the top opening on the flat bag |
| Gusset | On a stand up bag, the depth the base expands to when filled |
| Seal allowance | The sealed margin at the sides and the top, which is not usable space |
| Headspace | The gap you leave at the top so the bag can be sealed and stay flat |
A flat bag with no gusset holds less than its dimensions suggest, because as it fills it draws in from the sides. A gusseted bag converts some of that length into base depth and stands upright on a shelf, which is a merchandising decision as much as a capacity one.
Why volume ratings mislead
Bags are often described by what they hold, but that rating assumes a particular product density and a particular fill. Ground product settles and packs tightly. Whole or irregular product traps air and takes far more volume for the same weight. If you have seen a bag rated for a weight and found your product does not fit, this is why.
The reliable method is physical. Fill your product into a bag you already have, or into a measuring container, and record the volume it actually occupies packed the way you will pack it. Then size against that, plus headspace.
Choosing a size in order
- Measure the packed volume of one unit of your product.
- Decide flat or stand up, since that changes the shape of the space.
- Add headspace at the top so the seal area stays clean and product-free.
- Check the filled bag against your shelf, your shipper or your display box.
- Confirm the print area, because a gusset and a seal zone reduce the panel you can actually design on.
Design notes that save a reprint
- Keep critical artwork and barcodes away from the seal margins and the gusset fold.
- Remember the back panel is where most required text lands, so plan it, do not squeeze it.
- A hang hole has to be positioned in a sealed area, not through the product cavity.
- A resealable closure takes vertical space, so add it to your length before you finalise.
Ordering
Minimum order is 100 units and bulk pricing starts at about $0.48 per unit, confirmed on your written quote once size, material and print are fixed. Design support, free US shipping and a digital proof before anything prints are included. Turnaround is stated per product across three lanes: rush (expedited production plus air freight), standard (air) and cost saver (sea), from about 7 business days plus 2 to 5 for delivery, with specialty imported items running up to about 12 weeks. Production is at our West Chicago plant in the United States and our Guangzhou plant in China.
For stand up formats specifically see stand up pouch dimensions, and for the wider sizing reference see pouch dimensions. Send your measured packed volume and your quantity to /quote/ and we will size against your product rather than a chart.
