Back Seal Bag | Custom Pillow Bags with Fin or Lap Seal

Product Details

Overview & Specifications

What Is a Back Seal Bag?

A back seal bag is a flexible package formed from one web of film that wraps around and is joined down the back with a longitudinal seam, then closed with cross seals at the top and bottom. When filled, it takes the familiar pillow shape seen on chips, candy and other dry goods. Because the seam runs down the back, the front panel carries the main artwork without interruption.

How a Back Seal Bag Is Formed

The format is built from a single film web and three seals.

Rear Longitudinal Seal

The film edges meet at the back and are sealed into one vertical seam running the full height of the bag.

Back view of a back seal bag showing the vertical longitudinal seal running the full height of the package.

Top and Bottom Cross Seals

Horizontal seals close the bottom before filling and the top after filling, so the finished pack is sealed on all sides.

Pillow Profile When Filled

Without a gusset or base, the filled bag rounds out into a pillow shape, with the final profile set by the product's flow and the air left in the pack.

Fin Seal vs Lap Seal

The rear seam is built one of two ways, chosen around the film and the equipment.

Fin seal

How it is builtThe inner sealant surfaces are pressed together, leaving a small fin standing off the back

Typically suited toMost laminates, since it seals inside layer to inside layer

Lap seal

How it is builtOne film edge overlaps the other and seals flat

Typically suited toFilms with appropriate sealable surfaces; lies flatter against the back

The final seam type is confirmed against the film structure and filling equipment.

Anatomy of a Back Seal Bag

01

Front Panel

Primary branding and product communication, uninterrupted by a seam.
02

Back Panel

Ingredients, directions and barcode, laid out around the rear seam.
03

Rear Longitudinal Seam

The fin or lap seal running the height of the bag.
04

Top and Bottom End Seals

Cross seals that close the pack, typically about 10–15 mm each.
05

Easy-Open Zone

Tear notch and hang hole, where specified, near the top seal.

Artwork note: Keep barcodes and key copy off the rear seam and clear of the end seals; plan the back panel as two halves either side of the seam.

Application guide

When Is a Back Seal Bag the Right Choice?

A back seal bag works well when a dry or free-flowing product suits a pillow-style pack and a clean front face, such as chips, snacks, candy, grains and single-serve dry foods.

01

Pillow

Familiar Pillow-Pack Format
The filled bag forms the pillow profile buyers already recognize from snack and confectionery aisles, and it works for stacked, horizontal, hanging and secondary-display presentation.
02

Brand

Seam-Free Front Branding
The longitudinal seam stays on the back, leaving the front face uninterrupted for the main visual identity and product information.
03

Line

Form-Fill-Seal Production Fit
The structure is suited to continuous forming and filling when the film, sealant layer, registration, dimensions and equipment are matched. Performance depends on the complete machine and material setup.
04

Alternative

When Another Format May Fit Better
If both faces need to stay seam-free for artwork, a 3 Side Seal Pouch is the closer flat format. For upright shelf display, choose a Stand Up Pouch or a Flat Bottom Bag.

Back Seal Bag Specifications

Back seal bags are developed around the product, film web, rear-seal construction, end seals and compatible filling equipment.

Specification	Available Configuration
Product Type	Back Seal Bag / Back Seal Pouch
Category	Mylar Bags
Custom Dimensions	Custom finished width and length, developed around the product and machine requirements
Rear Seal Options	Fin seal or lap seal, selected according to film and equipment
End Seals	Top and bottom cross seals, typically about 10–15 mm each
Reference Fill Range	Single-serve snack bags to family-size packs, product-volume dependent
Materials	PET film, clear PET film, metallized PET film, holographic PET film, kraft paper laminate where compatible
Functional Features	Tear notch, hang hole and clear window
Print Methods	Digital, flexographic and rotogravure
Print Coverage	Front only, front and back, or full wrap planned around the rear seam
Print Colors	Full-color CMYK and Pantone spot colors
Coating / Lamination	Gloss, matte and soft-touch; interior aluminum foil where required
Finishes	Foil stamping, Spot UV and Raised 3D UV
Food-Contact Documentation	Applicable testing and documentation can be arranged per order for the selected construction and destination market
Starting Price	From $0.55 / unit; final price depends on size, material, printing, features, finishes and quantity
Minimum Order	500 units
Standard Production	7 days from approved proof after final specification
Rush Production	Available on request
Shipping	USA and worldwide

How Back Seal Bags Compare to Other Pouch Formats

The two flat formats differ mainly in where the seams sit; the gusseted formats differ in whether the pack stands.

Attribute	Back Seal Bag	3 Side Seal Pouch	Stand Up Pouch	Flat Bottom Bag
Seam layout	Rear longitudinal seam + top and bottom seals	Three perimeter seals + final filling seal	Side seals + folding bottom gusset	Corner seals + sealed flat base
Printable surfaces	Seam-free front; back split by the seam	2 clean faces	2 primary faces + gusset area	5 defined panels
Filled presentation	Pillow-style	Slim, flat profile	Upright, flexible profile	Structured, box-like footprint
Self-standing	Typically no	Typically no	Yes, when correctly sized and filled	Yes, when correctly sized and filled
How it is filled	Often formed and filled on form-fill-seal equipment	Premade, filled through the open edge	Premade, filled through the top	Premade, filled through the top
Main sizing variables	Width, length, seal allowances and headspace	Width, height, seal width	Width, height, bottom gusset	Width, height, side gussets and base
Production consideration	Strong machine and film-web dependency	Opening orientation and final seal	Gusset expansion and closure position	Base and gusset expansion, case fit
Best fit	Pillow packs for snacks and dry goods	Samples, portions and compact packs	Versatile upright retail packaging	Defined shelf footprint and five-panel presentation

What Size Back Seal Bag Do You Need?

Size a back seal bag from the product's volume plus the allowances the seals and headspace need, not from net weight alone. Bulky products like chips need far more bag than the same weight of nuts or candy, and every bag also loses length to its top and bottom seals.

Common Back Seal Bag Sizes for Snacks

These are reference starting points for chips and light snacks, listed as width × length.

Fill Weight (chips/snacks)	Approx. W × L	Typical Use
~0.7–1 oz (20–30 g)	4 × 6 in (100 × 150 mm)	Single-serve, vending, lunch packs
~2–3 oz (56–85 g)	5 × 8 in (125 × 200 mm)	Snack and sharing packs
~5–6 oz (140–170 g)	6 × 10 in (150 × 250 mm)	Retail snack bags
~6–8 oz (170–225 g)	6.3 × 10.6 in (160 × 270 mm)	Family-size packs

Denser products such as nuts, candy or grains fit the same weight into a noticeably smaller bag.

Important: These sizes are reference values, not guaranteed fills. Product volume, density, settling, seal widths, gas flushing and required headspace all change the final dimensions. A trial fill should be completed before the production dieline is approved.

If your product is not listed, share the product and target fill weight with the quote request so the bag can be sized around it.

How Is Back Seal Bag Length Calculated?

Bag length is the product height plus the top and bottom seals and the headspace. Each end seal typically takes about 10–15 mm, and headspace usually adds 20–40 mm, more for airy snacks or gas-flushed products. So a product needing 150 mm of fill height typically needs a bag around 190–220 mm long. Across the width, the film web must also allow for the rear seam: a fin seal uses extra film for the fin, which is material planning rather than usable artwork width.

Customization

Customize Your Back Seal Bags

Back seal bags are developed around the product, forming equipment, rear-seal type, film structure and artwork layout.

Dimensions and Machine Range

Width and length are configured around product volume, density, desired pack profile and the forming range of the filling equipment. Reference sizes are listed in the size guide.

Fin Seal or Lap Seal

A fin seal joins the inner sealant surfaces and leaves a projecting fin, while a lap seal overlaps the web edges. The right seam depends on the film structure, sealant requirements and machine setup.

Film and Barrier Structure

Choose from PET Film, Clear PET Film, Metallized PET Film, Holographic PET Film and Kraft Paper Laminate where compatible. The film is selected around moisture, oxygen, aroma, light and puncture while keeping the sealant and forming behavior the packaging line needs.

Product	Main Protection Considerations	Typical Direction
Chips and fried snacks	Oxygen, light and grease; rancidity	Typically metallized PET, often with gas flushing
Candy and confectionery	Moisture and product visibility	Clear, metallized or foil structures according to the product
Grains and dry mixes	Moisture and puncture	Typically metallized PET or another moisture-barrier laminate
Bakery and dry foods	Moisture, staling and aroma	Barrier selected around the product's shelf-life needs
Coffee and tea	Aroma, oxygen and light	Typically metallized PET or interior aluminum foil

A broader comparison of film structures is available on the Mylar Bags page.

Artwork and Finishes

Front artwork stays visually clear, while the back layout is designed around the longitudinal seam. Digital, flexographic and rotogravure printing support full-color CMYK, Pantone colors and compatible matte, gloss and specialty finishes.

For better finished artwork:

Split the back panel layout either side of the seam.
Keep barcodes off the seam and on a flat area.
Allow for print registration on form-fill-seal lines.
Keep key copy clear of the top and bottom seals.

Recyclable and Compostable Options

Recyclable mono-material and compostable structures can be developed for back seal bags where the product's barrier, sealing and forming needs can still be met. Claims depend on the final material system and the recovery route in the destination market.

Food-Contact Compliance, Testing and Documentation

Food-contact requirements are matched to the actual product, laminate construction and destination market. For U.S. projects, applicable FDA provisions are selected by material, such as 21 CFR 177.1520 for olefin polymer layers or 21 CFR 175.300 for certain coatings. For EU projects, requirements can include Regulation (EU) No 10/2011, Regulation (EC) No 1935/2004 and bisphenol requirements under Regulation (EU) 2024/3190.

Supporting test reports and documentation can be arranged for the selected configuration when required; a report applies to the material or package actually evaluated. Food-focused options are covered under Food-Safe Mylar Bags.

Filling-Line Fit

Share the machine model, target bag dimensions, product, fill weight and forming requirements so film width, registration, seal areas and rear-seam construction can be checked before production.

Ordering

How to Order Custom Back Seal Bags

Ordering custom back seal bags takes five steps: share the product requirements, confirm the size and dieline, approve the artwork proof, move into production, and ship. Orders start at 500 units, with standard production in 7 days from approved proof after the final specification is confirmed.

01
Request a Quote

Share the product type, target fill weight, quantity, filling method or machine model and any requirements for film, barrier, seam type or finishes. Packaging Dock typically responds to quote requests within 24 hours.
02
Confirm the Size and Dieline

Width, length, seam type and seal allowances are developed around the product, fill method and required headspace. Packaging Dock then provides a custom dieline showing the printable areas, rear seam, end seals and any tear notch or window position.
03
Approve the Artwork and Proof

Artwork is prepared on the dieline with free design support available. The proof is reviewed for panel layout, seam position, seal clearances, barcode placement, finishes and other specified features before approval.
04
Production

Production begins after the artwork proof and final specification are approved. Standard production is 7 days from approved proof, with rush production available on request.
05
Shipping

Finished back seal bags ship across the USA and worldwide. Transit method, delivery time and shipping cost depend on the destination, order volume and shipment requirements.

Sample note: A pre-production sample can be arranged when the project requires physical approval before the full production run.

Uses

What Are Back Seal Bags Used For?

Back seal bags are commonly used for chips and snacks, candy and confectionery, grains and dry mixes, and bakery and single-serve dry foods, where a pillow pack and a clean front face suit the product.

01
Snacks, Chips and Savory Foods

Chips, crackers and other dry snack products can use a back seal format with the film and barrier selected around product protection and filling requirements. More formats are covered under Food & Beverage Packaging.
02
Candy and Confectionery

Wrapped sweets, candy and compatible confectionery can use the seam-free front face and repeatable pillow-pack format for retail packaging. More formats are covered under Candy & Sweets Packaging.
03
Powders, Grains and Dry Mixes

Grains, powdered ingredients and dry mixes can use back seal bags when the film, seal construction and filling equipment are matched to the product's flow characteristics.
04
Bakery Items and Single-Serve Dry Foods

Compatible dry bakery items and portioned foods can use customized dimensions and tear features according to product shape, handling and production method. More formats are covered under Bakery Packaging.

Structures

Explore Other Mylar Bag Structures

Back seal bags are one of five core Mylar bag structures. Compare the other pouch formats below, or explore the complete Mylar Bags range.

Flat bottom coffee bags with a structured base

Flat Bottom Bag

Uses a distinct flat base and two side gussets to create a structured box-like footprint with five printable panels.

Stand Up Pouch

Uses a bottom gusset that expands to help the pouch stand upright, making it suitable for a wide range of retail products.

3 Side Seal Pouch

A flat pouch sealed on three sides, commonly used for samples, single-serve portions and compact product formats.

Spout Pouch

Combines a flexible pouch with an integrated fitment and closure for controlled pouring or dispensing.

FAQ

Back Seal Bag FAQs

What is a back seal bag?

A back seal bag is a flexible package formed with a longitudinal seal along the rear panel plus top and bottom end seals. When filled, it typically creates a pillow-style bag.

What is the difference between a fin seal and a lap seal?

Both are rear-seam constructions. A fin seal joins the inner sealant surfaces and leaves a fin at the back, while a lap seal overlaps the film edges and lies flatter. Lap seals need a film that seals on both surfaces; the right option depends on the film structure and packaging equipment.

Are back seal bags the same as pillow bags or center seal bags?

These terms are commonly used for closely related rear-seamed pillow-pack formats. Pillow bag describes the filled shape, and center seal bag describes the seam position. The exact fin or lap construction is still confirmed for the project.

What is the difference between a back seal bag and a 3 side seal pouch?

A back seal bag uses a longitudinal rear seam and top and bottom cross seals. A 3 Side Seal Pouch is a flat pouch with perimeter edge seals and no center seam across the back panel.

Do back seal bags stand upright?

The standard format is a pillow-style bag rather than a self-standing package. For a defined upright base, use a Stand Up Pouch or Flat Bottom Bag.

Are back seal bags suitable for vertical form-fill-seal equipment?

They can be developed for compatible form-fill-seal equipment, but the machine model, film width, seal type, registration and product characteristics need to be checked before compatibility is confirmed.

What size back seal bag do I need for a 1 oz snack?

A single-serve snack bag of about 0.7–1 oz of chips is commonly around 4 × 6 in. Denser products fit in smaller bags, so the size guide lists other reference sizes.

Can a back seal bag include a zipper?

Reclosure is not built into the standard rear-seam format. Compatible closure features may be possible on selected constructions, but they are confirmed against the bag design and filling equipment.

Can a back seal bag include a clear window?

A clear window may be possible where the selected laminate, print layout and barrier requirements allow it. Placement is coordinated with the rear seam and artwork.

What is the minimum order for custom back seal bags?

The minimum order is 500 units, with larger quantities quoted to the final specification.

How long does back seal bag production take?

Standard production is 7 days from approved proof once the final specification is confirmed, and rush production is available on request. Specialty materials, testing or complex configurations may need more time.

How much do custom back seal bags cost?

Pricing starts from $0.55 per unit. The final unit price depends on bag size, film, quantity, printing method, features, finishes and any project-specific testing. Quote requests typically receive a response within 24 hours.

Which film structure should I choose?

It depends on what the product needs protection from. Metallized PET suits many chips and snacks, foil laminates suit products needing a higher barrier, and clear films or a window work where the product should show.

Are back seal bags food safe?

Food-contact materials are selected around the packed product and destination market, and applicable FDA or EU testing and documentation can be arranged per order for the final construction. Food-focused options are covered under Food-Safe Mylar Bags.

Are back seal bags recyclable or compostable?

They can be built in recyclable mono-material or compostable structures where the product's barrier, sealing and forming needs can still be met. Claims depend on the final material and the applicable certification or recovery route.

Can I get a sample before ordering?

Yes. Complimentary sample kits ship within two business days; the customer covers shipping. Pre-production samples can also be produced for approval before the full run.

Where do you ship back seal bags?

Orders ship across the USA and worldwide. Transit method, delivery time and shipping cost depend on the destination, order volume and shipment requirements.

What artwork file formats can I submit?

The quote form accepts PDF, JPG, PNG, WEBP, TIFF, AI, EPS and PSD files, up to 3 files at 8 MB each, and a custom dieline with free design support is provided for the final bag.