Enter the final diameter of the tube and the die diameter into the calculator to determine the blow up ratio.

## Blow Up Ratio Formula

The following equation is used to calculate a Blow Up Ratio.

BR = Df / Dd

- Where BR is the Blow Up Ratio
- Df is the final tube diameter
- Dd is the die diameter

To calculate a Blow Up Ratio, divide the final tube diameter by the die diameter.

## What is Blow Up Ratio?

Definition:

A blow up ratio is a term used in blown film problems to describe the ratio of the final tube diameter to the die diameter.

## How to calculate Blow Up Ratio?

Example Problem:

The following example outlines how to calculate a Blow Up Ratio.

First, determine the diameter of the die. In this example, the die being used is measured to have a diameter of 5 inches.

Next, determine the final tube diameter. The final tube diameter made with this die yields a diameter of 6 inches.

Finally, calculate the Blow Up Ratio using the formula above:

BR = Df / Dd

BR = 6 / 5

BR = 1.2