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Views: 0 Author: Hengyi Packaging Publish Time: 2026-11-05 Origin: Hangzhou Hengyi Packaging Material Co., Ltd.
Buyer guide · Published 5 November 2026 · Hengyi Packaging
To estimate the raw-material effect of a resin price change, multiply the applicable resin weight per bag by the change in that resin’s price per kilogram. This is a sensitivity calculation, not a complete bag quotation. It helps purchasing teams translate a per-tonne material discussion into a meaningful per-piece question.
Film inspection in production. This photograph does not establish a measured result for the hypothetical bag weights in this guide.
One metric tonne is 1,000 kg. A hypothetical resin change of RMB 300 per tonne is therefore RMB 0.30 per kg. If a bag contains 20 g of the resin being repriced, that is 0.020 kg. Multiplying 0.020 by 0.30 gives RMB 0.006 per bag, or RMB 6 per 1,000 bags. The example does not say resin has actually fallen by RMB 300, or that Hengyi is offering that reduction.
Illustrative raw-material change per bag
Applicable resin mass (kg/bag) × resin change (RMB/kg)
20 g ÷ 1,000 × RMB 300 ÷ 1,000 = RMB 0.006 per bag
Illustrative applicable resin mass | Effect of RMB 300/tonne decrease | Per 1,000 bags |
|---|---|---|
5 g/bag | RMB 0.0015/bag | RMB 1.50 |
10 g/bag | RMB 0.0030/bag | RMB 3.00 |
20 g/bag | RMB 0.0060/bag | RMB 6.00 |
50 g/bag | RMB 0.0150/bag | RMB 15.00 |
All rows are arithmetic illustrations for a decrease in the price of the applicable physical resin. They are not observed bag weights, a live market move, a supplier cost sheet or a final sales discount.
A carton’s gross weight includes outer packing. A roll’s gross weight may include its core. Neither is automatically the mass of resin in a bag. A complete bag may also contain a zipper, slider, adhesive, printing or another component that is not priced using the same PE benchmark. When only one resin in a blend changes price, apply the calculation only to its relevant mass, with the blend confirmed.
A theoretical film-body weight can help with preliminary planning, but it must identify dimensions, single-wall thickness, structure and density assumptions. It is not an actual complete-bag weight. Gussets, handles, sealing allowances, closures and production variation can change the relationship. Use an agreed sample or a clearly labelled estimate, and keep quantity and weight units separate.
The simple formula holds the other inputs constant. Actual resin consumption per accepted bag can differ from the material in the finished item because of trim, setup and production yield. If that basis is used, identify it explicitly. Do not silently add an assumed waste percentage. Printing, tooling, packing, freight, taxes and the agreed selling basis require their own comparison.
Blown-film production: converting resin into film involves processing steps beyond the raw-material purchase.
For a bag buyer, a material-market number becomes useful when it can be related to the specified finished piece. Our recommendation is to agree the weight basis first: a complete-bag sample weight, or a clearly identified theoretical film-body estimate. Carton gross weight and a roll's core-inclusive weight should not quietly take its place.
We also recommend separating the inputs being compared. The PE resin component, zipper or closure, printing, conversion and packing are different parts of the discussion. The calculation in this guide isolates an illustrative resin change; it is not a Hengyi selling price. Buyers should request the resulting per-piece offer for the actual quantity and delivery terms, while keeping any weight assumptions visible.
Only as a clearly labelled scenario. A futures change does not establish the actual purchase-price change for the physical grade used in the bag. Use the applicable physical resin change for a purchasing calculation.
Ask for a per-piece or per-1,000-bag price at the specified quantity, with any applicable weight basis explained separately. Film rolls can use a different agreed unit. The formula above does not replace a commercial quotation.
Not necessarily. The calculation isolates one cost input under stated assumptions. A revised quotation must also reflect the unchanged specification and agreed commercial scope.
Check thickness terminology in the single-wall thickness guide before comparing estimates.
Hangzhou Hengyi Packaging Material Co., Ltd. supplies custom PE packaging. Review our clear and printed PE flat bags or PE film roll range, then send your bag drawing, single-wall thickness, material, artwork and order quantity. Ask for the applicable price unit, quotation validity and delivery terms. A market headline does not replace an agreed quotation.
