One of the biggest procurement decisions in PET packaging is whether to buy preforms and blow your own bottles, or buy finished bottles ready to fill. The answer is mostly about freight, volume and whether you run — or can justify — a blow-moulding line.
Finished bottles ship air
A blown bottle is mostly empty space, so a truck or container of finished bottles is carrying mostly air. Freight per unit is high, and the further the goods travel, the worse that maths gets. For long-distance or export supply, paying to ship air dominates the landed cost.
Preforms ship compact
A preform is a dense test-tube shape, so you fit far more preforms than bottles in the same container — often an order of magnitude more (see preforms per 40ft). That collapses freight per unit, which is exactly why beverage producers import preforms and blow them near the filling line.
The catch: you need a blow line
Buying preforms means running a reheat stretch-blow (SBM) line — capex, floor space, operators and maintenance. That is the trade-off: lower freight and full format/spec control, against the cost and complexity of blowing yourself. See single- vs two-stage for the process side.
When to buy finished bottles
Lower volumes, no SBM line, a local supplier within short trucking distance, or many small SKUs where a blow line cannot be kept busy — buying bottles avoids capex and complexity.
When to buy preforms
High, steady volume; export or long-distance supply where freight dominates; an existing or justifiable SBM line; and a need to control the exact preform spec, neck and weight. At scale, the freight saving alone usually pays for blowing in-house.
Work the numbers
Compare landed cost both ways for your real volume and distance, then factor SBM capex and run cost. Delta El Nile for Industry supplies preforms for two-stage lines worldwide — build an RFQ or read how to cut packaging cost.