Blister material cost: calculate forming and lidding webs separately

The purchasing question

A blister pack consumes both forming material and lidding material. These can have different GSM values and kilogram prices. A single average film price or thickness can hide which component drives cost and may produce a misleading mass estimate.

Calculation method

For each web, calculate area per machine repeat from width and pitch, then divide by packs across the repeat. Multiply area per pack by that web’s GSM ÷ 1,000 and price/kg. Add the two material contributions and apply a consistent loss model.

Worked example

A 0.3 m wide web with 0.1 m pitch and three packs per repeat uses 0.01 m² per pack. At 350 GSM and €2/kg, forming material costs €0.007 per pack. Lidding at 60 GSM and €5/kg on the same area costs €0.003. Together that is €10 per thousand nominal packs, or about €10.5263 with 5% gross-input loss.

The calculation represents purchased-web area, not the surface area of the formed cavity. It does not qualify barrier, sealability or product suitability. If the two webs have different scrap streams or dimensions, calculate their losses separately instead of forcing a shared rate.

Checks before using the result

• Use the actual forming and lidding layouts.
• Keep prices and GSM distinct for the two materials.
• Separate material cost from machine, tooling and product costs.

Common questions