Wool Grades & Standards

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Learn more About Wool Fibers.

The following grades and grading standards for wool is from the United States Department of Agriculture (USDA).

Below you will find two different categories, so be sure to check the proper grouping. 

1. Grades of Wool
2. Grades of Wool Top - The wool top is the longer fibers resulting from the combing process are called tops, and are in a form ready for spinning.

Grades of Wool

Finer than grade 80's. Wool with an average fiber diameter of 17.69 microns or less and a standard deviation in fiber diameter of 3.59 microns or less.

Grade 80's. Wool with an average fiber diameter of 17.70 to 19.14 microns, inclusive, and a standard deviation in fiber diameter of 4.09 microns or less.

Grade 70's. Wool with an average fiber diameter of 19.15 to 20.59 microns, inclusive, and a standard deviation in fiber diameter of 4.59 microns or less.

Grade 64's. Wool with an average fiber diameter of 20.60 to 22.04 microns, inclusive, and a standard deviation in fiber diameter of 5.19 microns or less.

Grade 62's. Wool with an average fiber diameter of 22.05 to 23.49 microns, inclusive, and a standard deviation in fiber diameter of 5.89 microns or less.

Grade 60's. Wool with an average fiber diameter of 23.50 to 24.94 microns, inclusive, and a standard deviation in fiber diameter of 6.49 microns or less.

Grade 58's. Wool with an average fiber diameter of 24.95 to 26.39 microns, inclusive, and a standard deviation in fiber diameter of 7.09 microns or less.

Grade 56's. Wool with an average fiber diameter of 26.40 to 27.84 microns, inclusive, and a standard deviation in fiber diameter of 7.59 microns or less.

Grade 54's. Wool with an average fiber diameter of 27.85 to 29.29 microns, inclusive, and a standard deviation in fiber diameter of 8.19 microns or less.

Grade 50's. Wool with an average fiber diameter of 29.30 to 30.99 microns, inclusive, and a standard deviation in fiber diameter of 8.69 microns or less.

Grade 48's. Wool with an average fiber diameter of 31.00 to 32.69 microns, inclusive, and a standard deviation in fiber diameter of 9.09 microns or less.

Grade 46's. Wool with an average fiber diameter of 32.70 to 34.39 microns, inclusive, and a standard deviation in fiber diameter of 9.59 microns or less.

Grade 44's. Wool with an average fiber diameter of 34.40 to 36.19 microns, inclusive, and a standard deviation in fiber diameter of 10.09 microns or less.

Grade 40's. Wool with an average fiber diameter of 36.20 to 38.09 microns, inclusive, and a standard deviation in fiber diameter of 10.69 microns or less.

Grade 36's. Wool with an average fiber diameter of 38.10 to 40.20 microns, inclusive, and a standard deviation in fiber diameter of 11.19 microns or less.

Coarser than grade 36's. Wool with an average fiber diameter of 40.21 microns or more.

Grades of Wool Top

Wool Top is also referred to as worsted top, it is a continuous sliver from long, choice woolen fibers which are to be manufactured ultimately into worsted yarn. The combing operation takes out the short fibers from the desired, choice stock. The wool top is the longer fibers resulting from the process are called tops, and are in a form ready for spinning.

Finer than grade 80's. Wool top with an average fiber diameter of 18.09 microns or less and a fiber diameter dispersion that meets the following requirements:

• a. 25 microns and under-not less than 95 percent.
• b. 25.1 microns and over-not more than 5 percent.
• c. 30.1 microns and over-not more than 1 percent.

Grade 80's. Wool top with an average fiber diameter of 18.10 to 19.59 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 25 microns and under-not less than 91 percent.
• b. 25.1 microns and over-not more than 9 percent.
• c. 30.1 microns and over-not more than 1 percent.

Grade 70's. Wool top with an average fiber diameter of 19.60 to 21.09 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 25 microns and under-not less than 83 percent.
• b. 25.1 microns and over-not more than 17 percent.
• c. 30.1 microns and over-not more than 3 percent.

Grade 64's. Wool top with an average fiber diameter of 21.10 to 22.59 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 92 percent.
• b. 30.1 microns and over-not more than 8 percent.
• c. 40.1 microns and over-not more than 1 percent.

Grade 62's. Wool top with an average fiber diameter of 22.60 to 24.09 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 86 percent.
• b. 30.1 microns and over-not more than 14 percent.
• c. 40.1 microns and over-not more than 1.50 percent.

Grade 60's. Wool top with an average fiber diameter of 24.10 to 25.59 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 80 percent.
• b. 30.1 microns and over-not more than 20 percent.
• c. 40.1 microns and over-not more than 2 percent.

Grade 58's Wool top with an average fiber diameter of 25.60 to 27.09 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 72 percent.
• b. 30.1 microns and over-not more than 28 percent.
• c. 50.1 microns and over-not more than 1 percent.

Grade 56's Wool top with an average fiber diameter of 27.10 to 28.59 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 62 percent.
• b. 0.1 microns and over-not more than 38 percent.
• c. 0.1 microns and over-not more than 1 percent.

Grade 54's. Wool top with an average fiber diameter of 28.60 to 30.09 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 54 percent.
• b. 30.1 microns and over-not more than 46 percent.
• c. 50.1 microns and over-not more than 2 percent.

Grade 50's. Wool top with an average fiber diameter of 30.10 to 31.79 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 30 microns and under-not less than 44 percent.
• b. 30.1 microns and over-not more than 56 percent.
• c. 50.1 microns and over-not more than 2 percent.

Grade 48's. Wool top with an average fiber diameter of 31.80 to 33.49 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 40 microns and under-not less than 75 percent.
• b. 40.1 microns and over-not more than 25 percent.
• c. 60.1 microns and over-not more than 1 percent.

Grade 46's. Wool top with an average fiber diameter of 33.50 to 35.19 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 40 microns and under-not less than 68 percent.
• b. 40.1 microns and over-not more than 32 percent.
• c. 60.1 microns and over-not more than 1 percent.

Grade 44's. Wool top with an average fiber diameter of 35.20 to 37.09 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 40 microns and under-not less than 62 percent.
• b. 40.1 microns and over-not more than 38 percent.
• c. 60.1 microns and over-not more than 2 percent.

Grade 40's. Wool top with an average fiber diameter of 37.10 to 38.99 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 40 microns and under-not less than 54 percent.
• b. 40.1 microns and over-not more than 46 percent.
• c. 60.1 microns and over-not more than 3 percent.

Grade 36's. Wool top with an average fiber diameter of 39.00 to 41.29 microns, inclusive, and a fiber diameter dispersion that meets the following requirements:

• a. 40 microns and under-not less than 44 percent.
• b. 40.1 microns and over-not more than 56 percent.
• c. 60.1 microns and over-not more than 4 percent.

Coarser that grade 36's. Wool top with an average fiber diameter of 41.30 microns or over.

These grading details were retrieved & layout improved by Apparel Search in December 2019 from the USDA website.  You can check with the USDA for updates.

The attached .pdf file is the United States Standards for Grades of Wool.  This file is effective from December 21, 1968 (that is the most current update as of December 2019).  The file shows the grades and also shows information regarding how to measure.  You can check the USDA website to determine if they have released any updates after this time.

Learn about wool sheep grades such as worsted wool, boiled wool, virgin wool, etc.

Learn more about wool from the wool definition.