Four-Side-Seal vs Pillow Pack: What Actually Drives Cost

Four-side-seal and pillow packs cost differently in five places: film consumption (four-side-seal uses flat film cut to product width plus side seams; pillow wrap wraps the product and adds a fin and two end folds, so taller products consume more film per pack), achievable line speed, startup and changeover waste, tooling, and labor. The format itself is rarely the deciding cost — your product’s shape is. Flat products under roughly 10 mm thick usually run cheaper as four-side-seal; anything taller usually runs cheaper as a pillow pack.

Two formats, two pieces of math

Cost comparisons fail when they stay verbal. Both formats’ film math is simple enough to run on a napkin — and exactly what our bag size calculator automates.

Pillow pack (flow wrap) forms the bag around the product from a single roll of film. The film width has to cover the product width, fold up both sides of the product height, and leave a fin to crimp:

film width = product width + 2 × product height + fin allowance

bag length = product length + end allowance (loose) or product length + product height + constant (tight wrap)

Four-side-seal seals two flat webs around a flat product on all four edges. Product height barely enters the width math at all:

film width = product width + 2 × side seam allowance

bag length = product length + 2 × end seam allowance

Look at the two width formulas again — they are the whole cost story. A 20 mm-tall product adds 40 mm of film to every pillow pack and almost nothing to a four-side-seal sachet. A 60 mm-tall product adds 120 mm. Height is what you pay for in pillow wrapping, and what you don’t pay for in four-side-sealing.

The five cost drivers compared

Where each format wins

Four-side-seal wins on flat products

Medical patches, test strips, adhesive bandages, sugar-free sweets, seasoning sachets, flat wipes — products where thickness is a rounding error. You get a rectangular, retail-friendly sachet, seal integrity on four independent edges (a quality argument in regulated work), and multi-lane throughput that a single pillow lane can’t match. The format’s cost weakness is shape: anything thicker than roughly 10 mm starts to fight the sealing jaws, and the “flat film ignores height” advantage disappears when the product isn’t actually flat.

Pillow pack wins on real products with height

Biscuits, bread, soap bars, boxed goods, hardware blister packs — the physical world. The forming collar hugs whatever height you have, the pack is tolerant of product variation, and a single roll of plain or printed film with a back seal is the cheapest possible enclosure per cubic centimeter of product. Its cost weakness is exactly the mirror: every millimeter of height is two millimeters of film, and the fin seal is a permanent material surcharge.

The waste nobody prices in

Both formats lose material at startup and changeover — splices, temperature ramp-up packs, registration pulls on printed film. The difference is frequency, not size: a pillow line running one SKU all week loses film once; a four-side-seal line changing width three times a day loses it three times. When you compare formats, multiply your changeover count by your typical startup waste (ask any supplier for their measured number — if they don’t have one, that’s an answer too). This is also why the changeover question belongs in your pre-purchase question list.

Run your own numbers

The calculator at tool.path-pack.com implements both formulas exactly as written above — enter your product dimensions (Mode A) or a fill weight with a density range (Mode B), and it returns the film width and bag length each format requires, with a fit margin for shop-floor reality, then shows which machines hold that bag as standard. Two minutes there replaces an afternoon of arguing from brochures.

When you know your format: the four-side-seal machine range covers flat-product sachet work (the JC400 patch line is the typical entry point), and the flow wrapping range covers pillow work (most buyers start at the JC250).

FAQ

Is four-side-seal always cheaper than pillow wrap?

No — it is cheaper when your product is flat, because film width ignores product height. For tall products, four-side-seal stops being viable before it stops being cheap, and pillow wrap is both the lower-cost and the only-workable option. The crossover is product shape, not format preference.

How much more film does a pillow pack use?

Per pack, the difference equals 2 × product height + fin allowance minus 2 × side seam allowance. For a 30 mm-tall product with typical allowances, that’s roughly 60 mm of extra film width on every single pack. Whether that matters is a volume question — at a hundred packs a minute, it answers itself.

Which format is better for medical or regulated products?

Four-side-seal sachets are the common choice for flat medical devices and diagnostics — four independent seal edges suit validation and visual seal inspection. Solid, dimensional products (trays, boxed kits) still travel in pillow wraps; the regulatory question is seal integrity and process documentation, not the format name.

Can one machine do both formats?

No — they are different machine architectures (flat-web sealing versus forming-collar wrapping). What you can do is size each machine’s format envelope so your whole product portfolio fits one machine per format family, which the calculator’s fit-margin output is built for.

Want these formulas run for your product? → Send Path Pack your product dimensions and film — we will run the film math for both formats.