Pet food is heavy, oily and bought in bulk, and those three facts settle most of the packaging specification before design enters the conversation. Kibble normally leaves the extruder at roughly 8 to 10% moisture and 10 to 25% fat. The fat is the vulnerable part: it oxidises, and oxidised fat is what makes an animal refuse a bowl it ate without hesitation a month earlier.
The bag has to hold that off for the whole commercial life of the pack, which for dry food is usually 12 to 18 months on a shelf. This guide works through the decisions that actually change a specification: format by pack weight, pouch sizing from bulk density, barrier targets, nitrogen flushing, and the closure details that fail in the field. It is written for buyers and brand owners preparing a brief, not for a design award.
Direct answer. Dry kibble is normally packed in a PET/MetPET/PE or PET/AL/PE laminate as a flat-bottom (eight-side-seal), quad-seal or stand-up pouch, sized from a bulk density of about 0.35 to 0.45 g/ml, with a press-to-close zipper above roughly 500 g. Wet food needs a retort structure such as PET/AL/RCPP that survives sterilisation at about 121 ℃. Freeze-dried and high-fat recipes need the strongest moisture barrier in the range, because their failure mode is softening and aroma loss rather than rancidity.
Three ways pet food packaging fails
Nearly every complaint about a pet food bag traces back to one of three mechanisms, and they are not interchangeable.
Fat oxidation. Kibble carries 10 to 25% fat, and unsaturated fatty acids react with oxygen even at low concentrations. The first visible effect is not spoilage but refusal, because palatability falls before anyone notices an off smell. Oxidation also destroys fat-soluble vitamins A, D and E, so a diet can be nutritionally short while still looking and smelling perfectly normal.
Moisture uptake. Dry kibble sits at roughly 8 to 10% moisture. Once a pack draws enough water to cross about 12%, mould and bacterial growth become a real risk, and the pellets lose the texture that carries a brand's quality story. Moisture crosses a film far more readily than oxygen does, which is why the moisture barrier is usually the harder of the two targets to hit.
Mechanical failure. A 10 kg bag is an abrasive, angular load. Sharp kibble edges puncture the inner layer, pallet stacking compresses the seals, and a bag dropped from shelf height in e-commerce handling bursts at the corner. This one is engineering rather than chemistry, and it is solved by gauge, nylon reinforcement, seal width and handle design.
The order matters because it decides where the money goes. If the failure you are chasing is rancidity, a better moisture barrier will not help. If it is softening or mould, foil buys you less than it costs. Unlike roasted coffee, kibble does not release carbon dioxide after packing, so the one-way valve question that dominates coffee bags does not arise here at all.
Format by pack weight: what the trade actually uses
Weight is the first filter. A pouch that presents beautifully at 500 g becomes a liability at 10 kg, where load-bearing and puncture resistance take over from shelf presence. The bands below are the ones converters quote most often.
| Pack weight | Typical format | Closure | Notes |
|---|---|---|---|
| 50–200 g | Three-side-seal or flow-pack sachet | Tear notch or laser score | Treats, toppers, single serves |
| 200 g–1 kg | Stand-up pouch (doypack) | Press-to-close zipper | Mainstream retail dry food and treats |
| 1–5 kg | Flat-bottom (eight-side-seal) pouch | Zipper, handle optional | Best shelf stability; the premium band |
| 5–10 kg | Quad-seal or reinforced flat-bottom | Slider zipper, die-cut handle | Needs reinforced seals and heavier gauge |
| 10–25 kg | Side-gusset bag or laminated woven PP | Heat-sealed top, strap handle | Bulk, farm and shelter packs |
| 100 g–1 kg wet | Retort pouch | Tear notch only | Must survive sterilisation at about 121 ℃ |
Above roughly 25 kg, most brands leave laminated film behind and move to woven sacks or multiwall paper. That is the point where flexible packaging stops being the right answer, and a converter who tells you so is worth keeping.
Two format names are worth pinning down before you brief anyone. A flat-bottom pouch is also sold as an eight-side-seal or block-bottom pouch, and some suppliers use quad-seal for the same family while others use it for a side-gusset box pouch. Ask for a drawing rather than agreeing a name, because the same word covers different constructions depending on who is quoting.
Sizing a pouch: why a 2 kg bag is not 2 kg of pouch
Pet food is sold by weight and packaging is specified by volume, and the two only meet through bulk density. Extruded kibble typically runs at about 0.35 to 0.45 g/ml. Cold-pressed pellets are denser, freeze-dried pieces are far lighter, so the same 2 kg can need two quite different pouches.
| Product weight | Approximate product volume | Pouch volume to specify |
|---|---|---|
| 250 g | ≈ 620 ml | 700–800 ml |
| 500 g | ≈ 1,250 ml | 1,400–1,600 ml |
| 1 kg | ≈ 2,500 ml | 2,800–3,200 ml |
| 2 kg | ≈ 5,000 ml | 5,500–6,300 ml |
| 3 kg | ≈ 7,500 ml | 8,300–9,400 ml |
Headspace is the other half of the calculation. The zipper has to close with product still below it, and the bag has to stand at the target fill without the bottom sagging out of shape. A pouch filled to the brim cannot be sealed reliably; a pouch that is generous by 30% lets the load shift and the pack slump on the shelf.
The practical rule: never approve a pouch size from a render. Fill one with your real product on your real line, check the zipper closes without forcing, then check it again after a night in a carton. One sample run is cheaper than a container load of film that fits nothing.
Barrier targets: the numbers behind a 12–18 month shelf life
Barrier is quoted as two figures. Oxygen transmission rate (OTR, in cc/m²/day) measures how much oxygen crosses the film; water vapour transmission rate (WVTR or MVTR, in g/m²/day) measures moisture. Lower is better on both, and the two rarely improve together.
Published planning ranges for pet food are tighter than for most snack categories, because of the fat load. Dry kibble is commonly specified below about 5 cc/m²/day of oxygen and about 2 g/m²/day of moisture for a 12 to 18 month ambient shelf life. Wet, retorted food is stricter again, because after sterilisation the sealed pack is the only protection the product has left.
| Product | Main threat | OTR target (cc/m²/day) | WVTR target (g/m²/day) | Typical shelf life | Structure |
|---|---|---|---|---|---|
| Dry kibble | Moisture, fat oxidation | ≤ 5 | ≤ 2 | 12–18 months | PET/PE or PET/MetPET/PE |
| High-fat or freeze-dried | Moisture, oxidation, aroma loss | ≤ 2 | ≤ 1.5 | 12–24 months | PET/AL/PE or mono-PE with EVOH |
| Wet food (retort) | Oxygen, moisture loss | ≤ 1 | ≤ 2 | 18–36 months | PET/NY/AL/CPP |
| Treats and chews | Oxidation, aroma loss | ≤ 5 | ≤ 1 | 6–12 months | OPP/MetOPP/PE |
Treat these as planning ranges, not as a specification you can hold anyone to. Barrier depends on the whole structure and on the thickness of every layer, so a supplier can only be bound to a number that was measured on your own laminate. Ask for the test report rather than the brochure. ASTM D3985 is the standard oxygen method and ASTM F1249 the standard moisture method, and the report should name the exact structure and gauge it was run on.
Material structures, and where each one fails
Every layer in a laminate has a job. The outer layer carries print and takes abuse, a middle layer blocks gas or light, and the inner layer seals to itself. Reading a structure as three functions makes the trade-offs obvious.
| Material | Typical OTR (cc/m²/day) | Typical WVTR (g/m²/day) | Job in the structure | Where it lets you down |
|---|---|---|---|---|
| Polyethylene (PE) | 3,000–7,000 | 10–20 | Sealant layer, moisture resistance | Almost no oxygen barrier on its own |
| Polypropylene (PP) | 1,500–3,000 | 5–10 | Sealant, higher heat resistance | Stiff; weak oxygen barrier |
| Polyester (PET) | 50–100 | 15–30 | Print surface, mechanical strength | Not a barrier layer by itself |
| Nylon (PA / BOPA) | 30–100 | 150–300 | Puncture and drop resistance | Absorbs moisture; barrier falls when wet |
| EVOH (inside a laminate) | 0.5–3 | 20–40 | High oxygen barrier without foil | Barrier collapses as humidity rises |
| Aluminium foil | Near zero | Near zero | Complete light, oxygen and aroma block | Multi-material; hardest to recycle |
The choice usually comes down to three structures. A metallised laminate such as PET/MetPET/PE is the workhorse for dry food and treats: real light protection, moderate oxygen barrier, and a print surface that holds colour. An aluminium foil laminate is for premium and long-life export packs where aroma loss has to be close to zero, and the price you pay is a structure that will not separate cleanly in a recycling stream. A mono-PE pack with a thin EVOH layer is the recyclable route, and it carries a caveat worth understanding before you commit: EVOH absorbs moisture and loses much of its oxygen barrier as humidity rises, so it has to be sandwiched between moisture-resistant layers and its performance has to be confirmed on your own shelf-life test rather than taken from a datasheet.
Nylon earns its place on packs of 5 kg and up. It is the layer that absorbs the energy of a drop or a sharp kibble edge, and converters commonly add it as a reinforcement layer on heavy dog food bags rather than thickening the whole laminate. If your product goes into a freezer or a chill chain, the sealant layer also has to be rated for cold, and that is a different film from the ambient retail specification.
Nitrogen flushing: removing the air a barrier film cannot
The single most common specification mistake in this category is expecting the film to do a job that belongs to the filling line. A barrier film stops new oxygen getting in after sealing. It does not remove the air that was inside the bag when the seal closed, and a large kibble bag can trap one to three litres of it in the headspace and inside the porous pellet structure.
Nitrogen flushing displaces that trapped air before sealing. On a normal VFFS or premade-pouch line the headspace is brought below about 1% residual oxygen. High-fat recipes, generally above 18% crude fat, and freeze-dried or veterinary diets are usually run at higher nitrogen purity, from 99.5% toward 99.9%, because the fat load gives oxygen more to work on.
The effect is measurable and large. A controlled storage comparison reported in a pet food packaging patent measured malonaldehyde, the standard marker for fat oxidation, at roughly 6 mg/kg in kibble held in a freely permeable paper bag after four months of accelerated storage, against about 0.1 mg/kg for the same diet in a foil laminate with a near-zero oxygen transmission rate. Fixing the film without flushing gets you part of the way; flushing without fixing the film gets you the rest. You need both.
Two conditions apply. Flushing adds no moisture barrier, so a freeze-dried treat still needs the strongest film in the range even on a flushed line. And gas is wasted on a bag whose seal leaks, so verify seal integrity before you start paying for nitrogen.
Does pet food packaging need a degassing valve?
No, not for kibble. A one-way valve exists to let carbon dioxide out of a pack that keeps producing it, with roasted coffee as the obvious case, while keeping oxygen out. Extruded dry pet food does not generate carbon dioxide after packing, so there is nothing to release, and a valve adds both a hole in an otherwise sealed barrier and a small component that can clog with fat dust.
The exceptions are narrow. A few baked or fresh-style treats keep releasing trace volatiles for a short period after packing, and a valve can help there. If someone offers a valve on a standard kibble bag as a premium feature, treat it as decoration rather than protection.
The same logic runs through neighbouring categories for different reasons. Fine powders skip the valve because their real enemy is caking rather than oxidation, which the powder packaging guide sets out in detail. Nuts sit between the two, and the pecan and pistachio packaging guide explains why shelled and unshelled kernels need different moisture targets.
The parts that fail in the field: zippers, handles, seals and punctures
Once the film is right, the remaining complaints come from a short list of hardware details. Specify them explicitly, because they are cheap to fix at the drawing stage and expensive to fix after printing.
| Failure | Usual cause | What to specify |
|---|---|---|
| Zipper splits or tears out | Weak tape bond, zipper set too close to the top seal, fat dust in the track | Zipper rated for at least 50 open and close cycles; keep clear film above the zipper; recess it under a tear strip when tamper evidence matters |
| Seal bursts at the corner | Seal narrower than the fill weight needs, product or surface oil trapped in the seal | 12–15 mm seal width on 10–20 kg packs; filling and sealing arrangement that clears product from the seal area |
| Bag punctures in transit | Sharp kibble edges against a thin inner layer | Inner PE layer around 100–150 µm on heavy packs, plus a nylon reinforcement layer; rounded corners |
| Handle pulls out | Die-cut placed in unsupported film | Reinforcement tape or patch around the handle; strap handle from about 15 kg upward |
| Delamination in frozen or fresh packs | Cold crack at low temperature, freeze-thaw cycling | Cold-rated sealant layer, verified with a freeze-thaw cycle using real product |
| Pack fails on the shelf | Over-filling, or a bulk density assumption that was never tested | Sample fill with real product before approving the drawing |
Closure choice is worth a decision rather than a default. Press-to-close zippers are the standard from about 500 g upward. A slider zipper reads as more premium and is easier for older hands. A double zipper buys a second seal for freshness messaging at a cost that is hard to justify below the premium band. Heat seal only is still correct for single-use sachets and for retort pouches, where the closure has to survive the sterilisation cycle and a zipper would not.
If you want a number to hold a converter to, drop testing a full pack from about 1.5 m and repeating it is the usual acceptance test, for example against ASTM D5276, and handle strength is normally quoted against a standard pull test. Ask which methods were used and on what fill weight.
One more decision belongs here because it constrains everything above it: is the bag filled from roll film on a VFFS line, or supplied as a premade pouch? Roll film limits you to formats your machine can form. Premade pouches open up flat-bottom and window formats but add a packing step and cost. Choosing late means re-running the whole specification.
Compliance and recyclability: what changes under PPWR in 2026
If you sell into the European Union, packaging design stopped being a free choice in August 2026. Regulation (EU) 2025/40, the Packaging and Packaging Waste Regulation, applies from 12 August 2026, and its substance restrictions take effect immediately rather than phasing in.
Two numbers matter for pet food first. Food-contact packaging must stay below 25 parts per billion for any individual PFAS and 250 ppb for the sum of PFAS, a rule aimed at the grease-resistant coatings used on some treat bags and semi-moist pouches. Separately, the combined total of lead, cadmium, mercury and hexavalent chromium must not exceed 100 mg/kg. Metallic inks and pigments are the common source of the latter, which puts a printed kibble bag directly in scope.
Recyclability is graded rather than absolute. Packaging must reach at least grade C from 2030 and grade B from 2038, and the detailed design-for-recycling criteria sit in a delegated act that is still pending, so the exact tolerances may still move. The direction will not. A classic PET/foil/PE retort pouch, the format that dominates premium wet cat and dog food, is a multi-material structure that does not separate cleanly, and it is the hardest case in the whole category.
Recycled content phases in from 2030. One point to put to your compliance advisor rather than assume: whether pet food packaging qualifies for the softer contact-sensitive schedule is disputed in current commentary, and if it does not, the standard plastic recycled-content targets apply instead. That difference is measured in years of recyclate sourcing, so it is worth resolving early. In the same window, the Empowering Consumers for the Green Transition Directive becomes enforceable on 27 September 2026. It targets environmental claims that cannot be substantiated, with member-state fines set at a minimum of 4% of relevant annual turnover. Generic wording such as eco-friendly, green or sustainable sits at the top of the risk list, and a printed claim needs third-party certification behind it. In the United States, California's SB 54 producer-responsibility programme is in implementation, with registration and reporting running through 2026 and a 2032 target that single-use packaging sold in the state be recyclable or compostable.
What that means for a pet food brief:
- Ask the converter for a Declaration of Compliance covering every layer, ink and adhesive, and for the current EU 10/2011 and FDA 21 CFR position on the food-contact layer.
- Ask for barrier figures measured on your own structure and gauge, not a generic datasheet.
- If recyclability becomes a 2030 requirement for your market, plan a mono-PE or mono-PP structure with a thin EVOH barrier now, and confirm it on your fill weight and shelf life.
- Do not print green wording until someone can produce the certificate, format by format.
What to send a supplier for a pet food packaging quotation
Most quotation rounds lose a week because the first brief is missing three or four facts. Send these and the specification conversation starts in the right place:
- Product type and the numbers behind it: kibble, semi-moist, freeze-dried, wet or treat; typical fat and moisture content; whether the product is dusted or oil-coated.
- Pack weight per SKU and the SKUs you expect to launch, so the format family can be planned as a set rather than one bag at a time.
- Target shelf life and the storage conditions you are claiming, plus whether an accelerated test has been run.
- Filling method: VFFS from roll film, premade pouch, or hand-fill for the first production run.
- Closure and features: zipper type, handle, window, tear notch, hang hole.
- Destination market, because food-contact, labelling and packaging-waste rules follow the destination rather than the factory.
- Finished artwork, with the number of print colours and the finish you want.
- Any barrier figure you are contractually bound to, so the structure is quoted against a number rather than a description.
We produce custom pet food packaging across stand-up, flat-bottom, quad-seal, spout and roll-film formats, including stand-up pouches for dogs and cats, treat pouches, window packs and supplement pouches. The custom pet food packaging range is the faster entry point if you would rather start from the format than from the film, and the flat-bottom pouch guide covers the heavy-pack format in more depth. Briefs go through the contact page.
Frequently Asked Questions
What is the best material for pet food packaging?
Metallised laminates such as PET/MetPET/PE are the standard for dry food and treats, and aluminium foil structures such as PET/AL/PE are used where aroma loss has to be close to zero. Wet food needs a retort structure like PET/AL/RCPP. Recyclable mono-PE with a thin EVOH barrier suits shorter shelf-life dry food.
What packaging is best for dry dog food?
For retail packs up to about 1 kg, a stand-up pouch with a press-to-close zipper. Between 1 and 5 kg, a flat-bottom (eight-side-seal) pouch sits best on shelf. Above 5 kg, move to a quad-seal or side-gusset bag with reinforced seals and a handle. In every case the film should carry a metallised or foil barrier.
What size pouch do I need for 2 kg of kibble?
About 5,000 ml of product volume for extruded kibble at 0.35 to 0.45 g/ml, so plan a pouch of roughly 5,500 to 6,300 ml to leave headspace for the zipper. Freeze-dried pieces are much lighter and need a larger pouch for the same weight. Confirm both with a fill test.
Does pet food packaging need a valve?
No, not for extruded kibble. A one-way degassing valve is for products that keep releasing carbon dioxide after packing, such as roasted coffee. Dry pet food does not, so a valve adds cost and a potential leak path without protecting the product. A few baked or fresh-style treats that off-gas may still benefit.
What is the shelf life of dry pet food in a pouch?
Commonly 12 to 18 months at ambient conditions with a metallised or foil laminate, and 12 to 24 months for high-barrier structures in premium or export programmes. Shelf life depends on the fill, the fat level and the seal, so the figure should be supported by a test on the finished pack.
Do pet food bags need nitrogen flushing?
It is strongly recommended for fat-rich dry food. A barrier film stops oxygen entering but does not remove the air already in the bag, and a large kibble bag can trap one to three litres of it. Flushing brings headspace oxygen below about 1% and slows fat oxidation from the moment of packing.
What is the difference between a flat-bottom pouch and a quad-seal bag?
Often only terminology. A flat-bottom pouch, also called an eight-side-seal or block-bottom pouch, has four side seals and a folded bottom gusset. Some suppliers use quad-seal for the same family and others use it for a side-gusset box pouch. Ask for a drawing rather than agreeing a name.
Are pet food bags recyclable?
Mostly not in kerbside collection. Multi-material laminates with foil or metallised layers are not recyclable, and even mono-material flexible packs usually need store drop-off film collection rather than a kerbside bin. From 2030, packaging placed on the EU market must meet a minimum recyclability grade, which is pushing brands toward mono-PE and mono-PP structures.
What is the minimum order quantity for custom pet food packaging?
MOQ is set by the printing and lamination run rather than by the bag count, so it is quoted per design and per structure. A stock pouch with a printed label needs far fewer pieces than a heavy custom-printed bag. Ask for the figure against your exact SKU rather than a catalogue number.
How should I test a pet food pouch before ordering?
Fill samples with your real product on your real line. Check that the zipper closes without forcing it, that the bag stands at the target fill, and that the seal is clean of product and surface oil. Then drop a full pack from about 1.5 m, repeat it several times, and inspect the corners. A paper specification cannot show you a burst corner.