PP Woven Bag Weight & Costing Calculator

Raw material and conversion, both. The raw material is the PP or HDPE granule with its masterbatch and filler, the coating resin, the BOPP or metallised film, the printing ink, the stitching thread and any liner. The conversion is what each process costs to run — extrusion, weaving, lamination, printing, cutting and stitching — charged per kilogram that passes through it, with process waste carried forward at every stage because scrap is still paid for.

Work out the fabric area from the cut size, turn that area into grams using the GSM of each layer, add the component weights for patches, valve, ink and thread, then add process waste. That gives the kilograms one bag consumes. Multiply each material's kilograms by its effective rate, add the conversion cost per kilogram, and the total is the cost per bag.

Cost per kilogram is what the market quotes; cost per bag is what decides the margin, because the customer buys bags. The two are linked by the bag's weight, so the same rate per kilogram produces a different price per bag the moment the specification changes. A five gram difference on 1,00,000 bags is over 500 kg of resin.

Directly, because scrap is bought and paid for. It is a small number per bag and a large one per order, and it is never the same at every process: printing and lamination scrap finished laminate, which is the most expensive material in the bag, while weaving loses far less. That is why waste belongs inside the costing, per process, rather than in a contingency at the end.

Per process, per kilogram. Each process — tape extrusion, weaving, lamination, printing, cutting, stitching, packing — carries a rate covering its manpower, power and machine time. The kilograms passing through each process are multiplied by that process's rate, so a bag that skips lamination is simply not charged for it.

Use your own measured figure rather than a rule of thumb, because it varies by process and by construction. Plants commonly see two to five per cent overall on a plain stitched sack and more on a laminated or printed bag, where lamination and printing add their own losses. The calculator applies one overall figure; the desktop app carries waste per material and per process stage.

Cost every layer separately. A BOPP bag carries the woven fabric, the extrusion coating that bonds the film, the BOPP film itself, the ink and, on a metallised bag, the adhesive, and each has its own rate and its own waste. Blending them into one rate per kilogram is how plants lose money on their most expensive product. Use the Easy cost (quick estimate)BOPP bag calculation page for the weight, then apply the rates layer by layer.

GSM is the cost, in effect. Weight is area multiplied by GSM, and cost is weight multiplied by rate, so every extra gram per square metre flows straight into the price. Dropping fabric GSM from 80 to 78 on a 0.9 square metre bag saves about 1.8 grams per bag, or 180 kilograms of resin on 1,00,000 bags.

As often as they move, which for resin and film is weekly. What matters more is that each rate is dated: an approved quotation has to keep the rate it was costed at, so a later price change cannot silently rewrite a costing that has already gone to a customer. That is the difference between a calculator and a bag costing system.

No. They are example rates so you can see how material and conversion build up. Enter your own rates in the "Edit example RM prices" panel, or request a demo to cost with your own dated price master and process rates.

GSM = denier × (mesh + mesh) ÷ 228.6, because warp and weft carry the same count. For 900 denier tape at 10 × 10 mesh: 900 × 20 ÷ 228.6 = 78.7 GSM. Use the denier to GSM calculator for any mesh.

BOPP film GSM is micron × 0.92, so an 18 micron film adds about 16.6 GSM, plus the extrusion coating layer of typically 15 to 22 GSM. See the Easy cost (quick estimate)BOPP bag calculation page.

A block bottom, pasted or pinch bottom bag has a rectangular bottom and top formed from the tube, with pasted patches and optionally a valve. Its cut length includes the patch and the patch overlap, and the patches themselves add weight. See block bottom bag calculation.

They count the layers that carry weight. 1 Layer is bare woven fabric; 2 Layer adds the extrusion coating; 3 Layer adds the BOPP film; 4 Layer adds a metallised film. The calculator only asks for the layers a construction actually has.

GSM is grams per square metre of fabric; GPM is grams per running metre, which is what the loom operator weighs. GPM equals GSM multiplied by the fabric width in metres, and a tubular fabric counts its lay-flat width twice. Use the GSM to GPM calculator to move between them.

Divide a tonne by the bag weight, then allow for the waste each process adds before the bag is finished. The calculator works the other way round and shows what you actually plan against: the kilograms an order of a given quantity will need.

The component-wise breakdown, with the formula behind every intermediate value, is a feature of Nexora Sales & Costing. Request a demo and we will run your own bag specification through it.

A liner is a separate article with its own lay-flat width, length and seal, so it has its own page: the LDPE liner weight calculator. In the desktop app the liner is one line of the bag's Bill of Materials.

Yes. Every size on every calculator takes millimetres, centimetres or inches, and switching converts the value so the answer does not move. Roll lengths take metres, yards or feet.

It is accurate enough to check a quotation and to catch a mistake, using common plant defaults for fold, patch, valve and waste. It is not your plant. Fold allowances, patch depths, valve sizes, ink coverage and waste norms differ from one factory to the next, and a real quotation should run on your own constants and your own dated rates — which is what the desktop app does across 29 constructions.