Glass jar or retort pouch for pickles and sauces: how much carbon does the switch change per unit shipped?
Switching from a glass jar to a retort pouch usually cuts packaging carbon per unit by most of the jar's footprint, because a pouch weighs a few grams against a jar's few hundred. Work it out as pack mass x material factor, plus the pack's own share of road and sea freight, for each option.
What to include for each pack
- Primary pack: jar and lid, or pouch, by weighed mass per unit.
- Secondary pack: cartons and dividers. Glass often needs heavier cartons and partitions, so weigh those too.
- Freight of the pack itself: pack mass x tonne-km x factor for each leg, factory to port, sea, port to buyer. The food weighs the same in both, so it cancels out.
- Process differences: retort steam per batch if it differs between the two packs. Measure it rather than assume.
- Losses: breakage in glass and pouch leaks both waste product, which carries its own footprint.
Why glass mass dominates
A jar for a 500 g pickle weighs far more than the pouch for the same fill. Even though a multilayer laminate has a higher footprint per kg than glass, its mass per unit is so much smaller that the jar almost always comes out higher. Sea freight per tonne-km is low, so freight usually adds less than the material itself; on air freight, the gap widens sharply.
What the pouch costs you elsewhere
Glass is widely recycled and can be refilled; most retort laminates of PET, aluminium foil and polypropylene are not recyclable in practice. If your buyer asks for end-of-life emissions or recyclability, report them alongside the cradle-to-gate result rather than hide the trade-off.
Making a public claim
If you plan to tell customers that the pouch has a lower footprint, ISO 14044 treats that as a comparative assertion. Both packs need the same functional unit, such as 500 g of product delivered to the buyer's warehouse, the same boundary and data quality, and a public comparison needs an independent critical review panel.
Worked example: 500 g of pickle, India to a European port (factors assumed)
- Glass: jar 250 g at an assumed 1.0 kg CO2e per kg = 0.25 kg; steel lug cap 20 g at an assumed 2.0 = 0.04 kg; pack total 0.29 kg CO2e
- Glass freight: 0.00027 t x 500 km road x 0.0902 = 0.012 kg; 0.00027 t x 11,000 km sea x an assumed 0.01 = 0.030 kg
- Glass total: 0.29 + 0.012 + 0.030 = 0.33 kg CO2e per unit
- Pouch: 12 g at an assumed 8.0 kg CO2e per kg = 0.096 kg; freight 0.0005 + 0.0013 = 0.002 kg; total 0.098 kg CO2e
- Saving: 0.33 minus 0.098 = about 0.23 kg CO2e per unit
- On a 20,000 unit container: 20,000 x 0.234 = about 4,680 kg CO2e
The road factor is the Smart Freight Centre India default for a 12 to 20 t truck; the material and sea factors and the sea distance are placeholders. Use your supplier footprints and your forwarder's lane factor.
What Senseible does here
Senseible reads the packaging purchase invoices and freight bills you would use for the weights and distances, and keeps them as evidence for the comparison.
- Packaging footprint on export shipments
- Packaging end of life for food exporters
- Product carbon footprint calculator
Sources: ISO 14044:2006, Life cycle assessment, requirements and guidelines (comparative assertions) (iso.org), Smart Freight Centre, India Default GHG Emission Values V1.0 (May 2025), road table; GLEC Framework v3.0, GHG Protocol Product Life Cycle Accounting and Reporting Standard
Last reviewed 2026-10-19.