Sizing
What Size Pouch Does Your Product Need
A pouch is specified by the volume it has to hold, not by the weight printed on the front. Two products at the same declared weight can need pouches a size apart, because what fills a bag is bulk, and bulk varies more than most people expect. This is how to get to the right size before any tooling is cut.
Decided byBulk density, not weight
Written asWidth × height + gusset
BuiltTo your drawing
Minimum order1,000 pieces per artwork
Weight Is Not Volume, and Volume Is What Fills the Bag
A kilogram of rice and a kilogram of pet kibble are the same weight and nothing like the same size. The property that separates them is bulk density: how much a given volume of the product weighs, including the air trapped between the pieces. Everything about sizing follows from it.
The working method is simple. Divide the fill weight by the bulk density to get the volume the product occupies, then size the pouch so that volume fills roughly three quarters of it. The remaining quarter is headspace, and it is not waste: it is what lets the pack close, seal and settle without straining the seams.
| Product | Typical bulk density | 250 g occupies about | 1 kg occupies about |
|---|---|---|---|
| Whole bean coffee | 0.35 – 0.40 g/ml | 650 ml | 2,600 ml |
| Ground coffee | 0.40 – 0.45 g/ml | 590 ml | 2,350 ml |
| Loose leaf tea | 0.20 – 0.30 g/ml | 1,000 ml | 4,000 ml |
| Whey protein powder | 0.40 – 0.50 g/ml | 560 ml | 2,200 ml |
| Rice and grains | 0.75 – 0.85 g/ml | 310 ml | 1,250 ml |
| Dried fruit | 0.55 – 0.70 g/ml | 400 ml | 1,600 ml |
| Dry pet kibble | 0.30 – 0.40 g/ml | 710 ml | 2,850 ml |
| Ground spices | 0.45 – 0.60 g/ml | 480 ml | 1,900 ml |
| Snacks and crisps | 0.10 – 0.20 g/ml | 1,650 ml | 6,600 ml |
These are the ranges the trade works to and they are a starting point, not a substitute for your own product. Bulk density shifts with grind, moisture and how the product settles, so we ask for a sample or a measured figure before tooling is cut. Measuring it yourself takes a minute: weigh a litre jug of the product, and the weight in grams divided by a thousand is the bulk density in grams per millilitre.
How a Pouch Is Written Down
Every quotation states the size the same way, and reading it correctly avoids the most common sizing mistake.
- Width × height. The flat dimensions of the pouch laid out, in millimetres, before it is filled. Width is always given first.
- Plus gusset. Written as +80 or similar. On a stand up pouch this is the base fold; on a side gusset bag it is the side folds. It is stated separately because it is folded in when flat.
- The filled pack is shorter than the flat one. As the gusset opens out to take the product, the pack gains depth and loses height. A 150 × 250 +80 pouch does not stand 250 mm tall once filled.
- The seal is inside the height. The top seal takes 10 to 15 mm, and on a zippered pouch the zipper sits below it. Both come out of the usable space, not on top of it.
This is why we send a dieline before artwork rather than after. The dieline shows the fill line, the seal areas and the zipper position on the flat sheet, so a designer can see which part of the panel a customer will actually be looking at.
Headspace, and Why the Pack Looks Bigger than the Product
A pouch filled to the brim cannot be sealed reliably, cannot be reclosed and looks strained on a shelf. Filling to about three quarters is standard, and there are three reasons for it rather than one.
- The seal needs clean film. Product caught in the seal area is the single most common cause of a leaking pack. The gap keeps the jaws clean.
- The product settles in transit. A pouch filled to the top at the factory arrives looking under-filled anyway, because vibration compacts the contents. The headspace is where that settling goes.
- Gas needs somewhere to be. Nitrogen flushing and coffee degassing both need volume inside the pack. A nitrogen-flushed snack pack carries considerably more headspace than three quarters for exactly this reason.
If a pack has to look full on the shelf, the answer is a smaller pouch or a denser presentation, not a fuller fill. Tell us at the enquiry that shelf appearance is a priority and the size is chosen with that in mind.
The Fill Sizes That Recur Across Our Range
These are the weights and volumes that come up repeatedly across the catalogue, because they are the retail sizes the categories have settled on. Any size can be built to your drawing; starting from one of these simply means the format is well proven.
| Fill size | Usually packed as | Typical format |
|---|---|---|
| 1 g to 10 g | Samples, single doses, drip coffee | Three side seal, drip sachet |
| 100 g to 150 g | Small retail: tea, spices, supplements | Stand up pouch |
| 250 g | The coffee standard, worldwide | Side gusset, flat bottom |
| 500 g | Larger retail coffee, snacks, dried fruit | Stand up or flat bottom |
| 1 kg | Catering, protein, grains | Flat bottom bag |
| 2 kg to 5 kg | Pet food, rice, bulk dry goods | Flat bottom, with a handle where needed |
| 100 ml to 200 ml | Single-serve drinks, baby food, purees | Spout pouch |
| 5 L | Liquid refills, foodservice, syrups | Handled spout pouch |
Coffee is worth calling out because it is the one category where the printed weight is nearly universal. A 250 g coffee bag and a 250 g protein bag are not the same pouch: the coffee needs roughly a fifth more volume for the same declared weight, and it needs a degassing valve as well. See coffee bags and protein bags.
Getting It Right Before the Tooling Is Cut
Tooling is the one cost in a packaging project that cannot be undone, so the sizing is worth settling first. What we ask for is short.
- The product itself, or its measured bulk density. A sample answers more questions than a description.
- The declared fill weight or volume, and whether it is likely to change later.
- Whether the pack has to fit a fixture: a shelf height, a shipper case, a peg gap.
- Whether you fill by hand or on a line, and if on a line, its make and speed.
- Any feature that takes up space: a zipper, a valve, a spout, a tear notch.
From that we send a dieline and a stock sample in the nearest existing size, so the size can be judged in the hand before anything is committed. The rest of the sequence is on the how to order page.
Send Us the Brief
Tell us what goes in the pack, roughly how much of it, and where it is sold. That is enough for a specification and a price. Talk to the factory.
Frequently asked
Pouch Sizing Questions
How do I work out what size I need?
Divide the fill weight by the bulk density to get the volume, then choose a pouch about a third larger so the product fills roughly three quarters of it. Send us the product or its bulk density and we will do it with you.
How do I measure bulk density myself?
Fill a one-litre jug with the product, level it without pressing down, and weigh it. The weight in grams divided by a thousand is the bulk density in grams per millilitre.
Why does my 250 g pouch look half empty?
Almost always settling in transit rather than a short fill. Product compacts under vibration, so a pack filled correctly at the factory arrives looking emptier. Where shelf appearance matters, a smaller pouch is the fix.
Can I use one pouch size for two products?
Only if their bulk densities are close. Two products at the same weight but different densities will look very different in the same pouch, and one of them may not fit at all.
What does 150 x 250 +80 mean?
A pouch 150 mm wide and 250 mm tall lying flat, with an 80 mm gusset folded into the base. Once filled, the gusset opens out and the pack stands shorter than 250 mm.
Does the zipper take up space?
Yes. The zipper and the seal above it use 25 to 35 mm of the pouch height between them, which comes out of the usable volume rather than being added to it.
Can you match a competitor pouch?
Yes. Send the pack itself if you can, or its width, height and gusset with a photograph. We measure from the sample rather than working from the printed weight.
Do you have stock sizes?
Certain sizes recur across the catalogue and their tooling already exists, which saves a little time and cost. Any other size is built to your drawing, at the same 1,000-piece minimum.
How accurate does my fill weight need to be at enquiry?
Close is enough to start. We can quote and send a dieline from an approximate figure, and confirm the size once we have the product or a measured density.
What if I get the size wrong?
Before tooling, nothing is lost. After tooling, a size change means new cylinders and a new cutting die, which is why we send a stock sample in the nearest size before anything is cut.