The USDA, AMS, Cotton Program developed a new procedure to calibrate the micronaire component of the Zellweger Uster 900 automatic High Volume Instrument (HVI) through the use of air orifices to provide a more accurate calibration for the micronaire measurement. A pilot study was conducted on 25 HVI systems at four Cotton Program offices during the 2000 cotton classing season. Checklot results from the Cotton Program’s Quality Assurance Section indicate that the HVI systems calibrated with the air orifices had a higher reproducibility for micronaire than those calibrated by the traditional calibration cottons. The study also revealed that the air orifice calibration offers increased efficiency through a faster micronaire calibration and cost savings through reduced calibration cotton consumption. The Cotton Program plans to expand the micronaire orifice calibration to additional classing offices based on the positive results of this study.