Packaging cost is rarely just the unit price of a bottle or keg. Transport, warehousing, breakage, reverse logistics, and filling efficiency all contribute to the true cost of packaging across the supply chain. For beverage brands making strategic packaging decisions, understanding total cost of ownership — not just purchase price — is essential. This hub breaks down the logistics and financial economics of PET packaging, with practical frameworks for comparing alternatives and building the business case for change.
PET is dramatically lighter than glass. A 500ml glass bottle weighs 200–300g; the equivalent PET bottle weighs 12–30g depending on format. This weight difference cascades through the entire logistics chain. More product fits on a pallet, more pallets fit in a truck, and more trucks can be loaded per depot. For a brewery distributing 1 million bottles per year, switching from glass to PET can reduce the number of outbound deliveries by 30–40%, with a corresponding reduction in fuel cost, driver hours, and carbon emissions. Breakage during transport — a significant cost and waste factor for glass — is eliminated. Insurance costs for breakage risk fall. Load-outs are faster because lighter packaging is easier to handle. And at the retail or on-premise end, staff handling lighter packaging reduces handling time and injury risk. The logistics case for PET rarely requires detailed modelling to be compelling — the savings are visible and immediate.
One of the most significant logistics advantages available to high-volume beverage producers is on-site or near-site bottle blowing from preforms. A PET preform — the test-tube shaped precursor to a finished bottle — weighs the same as the finished bottle but takes up around one-twentieth of the volume. A 40-foot container that carries 100,000 finished 500ml PET bottles can carry 2 million preforms in the same footprint. For brands operating their own blow-moulding equipment, or co-packers who invest in stretch blow moulding lines, buying preforms rather than finished bottles can reduce inbound logistics cost by 80–90% and dramatically reduce warehouse storage requirements. The economics work at volumes above approximately 20 million bottles per year for most blow-moulding line investments, but contract blow-moulding is available at lower volumes through specialist suppliers.
Steel kegs have been the default for draught beverage distribution for decades, but the true total cost of ownership (TCO) of steel keg systems is frequently underestimated. Steel kegs require a full reverse logistics infrastructure: tracking systems, cleaning and refurbishment facilities, depot networks for collection and redistribution, and significant capital tied up in keg float stock (typically 3–5× the annual volume in keg count to allow for kegs in distribution, at outlets, and in cleaning cycles). PET kegs — whether one-way or returnable — change this equation materially. One-way PET kegs eliminate reverse logistics entirely, freeing capital and simplifying the supply chain at the cost of higher per-keg purchase price and end-of-life recycling requirement. Returnable PET kegs offer a middle path: lower per-trip cost than one-way, but lighter and easier to handle than steel, with a keg float requirement that is typically 30–40% lower than steel due to faster cycle times. The right choice depends on distribution geography, outlet density, and the operational capability of the filling organisation.
Cost per litre is the commercial lens that aligns packaging procurement, operations, and finance teams on a single comparable metric. It takes into account: the unit cost of the package (bottle, cap, label, sleeve), filled product yield (overfill allowance, wastage), logistics cost (inbound packaging, outbound product), filling line efficiency (line speed, changeover time, downtime rate), breakage and wastage rates, and end-of-life costs (deposits, collection, disposal). For beverage brands making material change decisions — switching from glass to PET, moving from steel kegs to PET kegs, or increasing rPET content — a cost-per-litre model is the most reliable way to surface the true financial impact across the whole operation rather than focusing on any single line item in isolation. Petainer's commercial teams work with customers to build cost-per-litre models as part of the specification and business case process.
