👤 By whycalculator Team 📅 Last Updated April 09, 2026
Blow Up Ratio Calculator
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This calculator calculates the ratio between the bubble diameter and the die diameter. It is essential in the film extrusion process.
You can input the tube and die diameters and their preferred measurement units (cm, inch, feet, mm, or meter). The calculator dynamically computes and displays the Blow Up Ratio (BUR).
How to Calculate Blow-Up Ratio (BUR)?
The following formula is used to calculate the blow up ratio:
Blow Up Ratio (BUR) = Bubble Diameter / Die Diameter
Here;
- Bubble Diameter: The diameter of the inflated bubble formed after the material exits the die.
- Die Diameter: The diameter of the die or the circular opening from which the material is extruded.
Example 1:
- Bubble Diameter: 30 cm
- Die Diameter: 15 cm
BUR = 30 / 15 = 2.0
Result: The bubble diameter is 2 times the die diameter.
Example 2:
- Bubble Diameter: 18 inches
- Die Diameter: 12 inches
BUR = 18 / 12 = 1.5
Result: The bubble diameter is 1.5 times the die diameter.
Example 3:
- Bubble Diameter: 1.2 meters
- Die Diameter: 0.6 meters
BUR = 1.2 / 0.6 = 2.0
Result: The bubble expands to twice the diameter of the die.
Blow Up Ratio Comparison Table
| # | Bubble Diameter (cm) | Die Diameter (cm) | Blow Up Ratio (BUR) |
|---|---|---|---|
| 1 | 20 | 10 | 2.0 |
| 2 | 25 | 10 | 2.5 |
| 3 | 30 | 10 | 3.0 |
| 4 | 35 | 10 | 3.5 |
| 5 | 40 | 10 | 4.0 |
| 6 | 45 | 15 | 3.0 |
| 7 | 50 | 20 | 2.5 |
| 8 | 55 | 20 | 2.75 |
| 9 | 60 | 20 | 3.0 |
| 10 | 65 | 20 | 3.25 |