Enter the diameter of the lap roller, the RPM of the lap roller, and the efficiency into the calculator to determine the yarn production.

Yarn Production Formula

The following equation is used to calculate a Yarn Production rate.

P = pi*D*S/36 * 60 * 1/840 * n

  • Where P is the production (lb/hr)
  • D is the diameter of the lap roller (in)
  • S is the rotational speed of the lap roller (rpm)
  • n is the efficiency of the system, (typically 75-90%)

This formula calculates the linear output of the roller per unit time, then converts into units of weight per time using the known value of 840 yards of yarn per pound, then multiplies by the efficiency to get the final result.

What is a Yarn Production?


Yarn Production is a measure of the total weight per unit time that a yarn machine can produce. In other words, it’s the output of the yarn roller.

How to Calculate Yarn Production?

Example Problem:

The following example outlines the steps and information needed to calculate Yarn Production.

First, determine the diameter of the yarn roller. In this case, the lap roller is measured to have a diameter of 10 inches.

Next, determine the rotational speed of the roller. This is measured to be 150 RPM.

Next, determine the efficiency of the roller. This roller runs at a 75% efficiency.

Finally, calculate the yarn production using the formula above:

P = pi*D*S/36 * 60 * 1/840 * n

P = 3.14159*10*150/36 * 60 * (1/840) * .75

P = 7.0124 pounds per hour