Why quotes for the same container differ
A 750 ml rectangular takeout box sounds like one product. In practice it can be thermoformed or injection molded, made in PP of different grades, weigh anything from a light single-use version to a heavy reusable one, come with a PP or PET lid, ship 200 or 300 sets per carton and carry a printed lid or none. Each of these choices moves the unit cost. A quote that does not state them cannot be compared with another quote, and the lower figure often turns out to be a different, lighter product.
The reference used throughout this note is the 750 ml PP box from a Huizhou partner plant: 170x115x51 mm and 19.6 g.
Resin and gram weight
For most plastic containers resin is the largest single cost, and the amount of resin is set by gram weight. A heavier piece costs more in material, takes longer to cool and fills a carton with fewer pieces of the same stack height. That is why the gram weight belongs on every quote. Across the partner plant ranges, single pieces run from 7.3 g for a 360 ml bowl to 39 g for a 1,500 ml box, and the category spans about 7-60 g per piece. Within one footprint the steps are gradual: 17 g at 500 ml, 18.3 g at 650 ml, 19.6 g at 750 ml and 22 g at 1,000 ml.
Resin grade matters too. A food contact grade with a supplier declaration costs more than a general grade, and clear grades, copolyester for reusable storage and PET for cold display each carry their own cost. Resin prices also move with the market; see resin price and order timing.
Process and cycle time
Thermoforming forms containers from PP or PET sheet. It is fast and suits thin-walled single-use items, but the sheet has to be extruded first and the trimmed skeleton is regrind. Injection molding fills a closed tool with molten resin; it makes thicker, stiffer and more detailed parts, and its cost per piece depends heavily on cycle time, the seconds per shot. Thick walls, deep parts and large storage boxes cool slowly, so each shot takes longer and the press produces fewer pieces per hour. See thermoformed vs injection molded containers.
Cavities and tooling
A mold with more cavities makes more pieces per shot, which lowers the cost per piece but raises the cost of the tool. Stock molds carry no tooling charge for the buyer, which is one reason stock programs are efficient. For a new mold, the tool is either paid separately or spread across an agreed volume. Cavity count, steel and ownership terms are covered in mold steel and cavity count.
Lids, inserts and parts count
Every extra part adds material, a separate molding or forming step and assembly. A separate lid, a sauce insert, a silicone seal, a pump and valve on a vacuum container, wheels and a scoop on a pet food bin: each one is a line in the cost. Sharing one lid across several depths, as the 170x115 mm series does from 500 to 1,000 ml, reduces lid tooling and stock.
Decoration and branding
Print adds a setup, a run and inspection. Sleeves and labels are usually the least costly ways to brand; printing on the lid or body costs more per piece and carries its own minimum, typically 10,000-50,000 pieces per item; embossing needs a mold insert or a new tool. Retail boxes for storage lines often cost a meaningful share of the item itself.
Packing and freight
Containers are light and bulky, so freight is charged by volume. Nesting decides how many pieces fit in a carton and how many cartons fit in a container. Partner plants pack thermoformed PP boxes at 200-300 sets per carton, injection cups at 300-500, PET cold cups at 1,000 and sauce cups at 2,000-5,000. A collapsible storage box that folds to about 47 mm high ships far more units per container than a rigid box of the same size. Inner bags, sleeves of 25-50, retail boxes and carton grade all add cost but reduce damage.
Documents, testing and inspection
Supplier declarations to FDA 21 CFR or EU 10/2011, third-party migration reports, PFAS statements for fibre packaging, pre-shipment inspection and loading supervision all carry a cost. They are part of the landed cost of a container that can be sold legally and without complaints, and are agreed per project.
Import duty sits outside the plant quote but inside the landed cost. Plastic food storage containers usually fall under HS 3924.10, general storage boxes under 3924.90, plastic packaging containers under 3923 and paper boxes under 4819. Rates change with trade policy, so the classification and the current rate are confirmed with your customs broker before the order, not after the goods arrive.
The factors in one table
| Factor | What moves it | How to control it |
|---|---|---|
| Resin | Grade, clarity, market movements | Fix grade in the spec; time orders sensibly |
| Gram weight | Wall thickness, size, process | State target weight and tolerance on every quote |
| Cycle time | Wall thickness, depth, cooling | Avoid unnecessary thick sections |
| Tooling | New mold, cavity count, steel | Start on stock molds; spread tools over agreed volume |
| Parts count | Lids, inserts, seals, valves | Share lids across depths |
| Decoration | Print method, colours, embossing | Use sleeves or labels for early runs |
| Packing and freight | Nesting, pack count, carton grade | Design for nesting; fix pack count |
| Documents and QC | Market, tests, inspections | Plan the file once per item and reuse it |
Reading a quote
A comparable quote states the material and grade of each part, the gram weight with tolerance, the process, the lid type, the pack count and carton size, any print, the MOQ and the documents included. Where one of these is missing, ask before comparing. The quantity on the quote also matters: a stock item from 1-10 mixed cartons and a custom item from 50,000-100,000 pieces sit on different cost bases, with typical reference ranges confirmed in writing per program on MOQ and lead time.
Send the specification through the quote form and the desk returns quotes from partner plants on the same basis, so the comparison is real.