Blown film calculators

Fast answers for film, rolls, bubbles, and line output.

Enter the measurements you already collect. Results update instantly, stay on your device, and use the same formulas developed for Plastic Film Partners.

Thickness from a cut sample

Calculate gauge

Gauge (mil) = sample weight ÷ (layflat width × sample length × 0.0303)

Film construction Folded / tubular (two sheets) Single sheet

Sample weight gramsSample width inchesSample length inches

Calculated result

—mil

Folded film counts both layers in the sample weight.

Cut-sample target

Calculate gram weight

Gram weight = layflat width × sample length × gauge × 0.0303

Layflat width inchesSample length inchesTarget gauge mil

Calculated result

—grams

Target cut-sample weight.

Real-time extrusion rate

Calculate gross line output

lb/hr = nip speed × gram weight × 1.5858 × rolls ÷ sample length

Nip speed ft/minSample weight gramsSample length inchesRolls running count

Calculated result

—lb/hr

Gross output across all rolls running.

Finished-roll estimate

Calculate roll length

Roll length (ft) = (sample length ÷ 12) × 454 × roll weight ÷ sample weight

Roll weight poundsSample weight gramsSample length inches

Calculated result

—feet

Estimated film length on the roll.

Bubble geometry

Calculate blow-up ratio

BUR = layflat width ÷ (1.5708 × die diameter)

Layflat width inchesDie diameter inches

Calculated result

—: 1 BUR

Bubble diameter divided by die diameter.

Machine-direction stretch

Calculate draw-down ratio

DDR = die gap ÷ (finished gauge × BUR)

Die gap milFinished gauge milBlow-up ratio ratio

Calculated result

—: 1 DDR

Die gap and film gauge must use the same thickness units.

Gusseted layflat breakdown

Break down gusseted width

Total unfolded = first number + second number · Window = first number − second number

Example notation: 48 × 36

Gusseted width first numberCombined gusset sides second number

Total unfolded width—inches

Center window—inches

Each gusset—inches, if equal

ASTM D1709 staircase helper

Dart impact 50% failure weight

P50 = lowest failed weight + increment × ((A ÷ N) − 0.5)

Starting weight gramsIncrement gramsNumber of impacts count

Ready

Set the test conditions, then start recording impacts.