http://www.usga.org/rules/equipment-rules.html#!rule-14613 false GROOVE MEASURING PROCEDURE SUMMARY OF GROOVE MEASURING PROCEDURE (The bracketed numbers refer to the corresponding paragraphs in Supplement A - "Guidance on How to Measure Grooves on Club Faces for Conformance to the 2008-2009 Rules of Golf - In The Field") Clean club face [1]; ink the edges of five grooves in a 0.5 inch wide band [2]. Check marking tool [1]; use it as described in full instructions [3] to scrape the edges of the inked grooves. Use the magnifier to measure the width of all five grooves, and record on the results sheet [4, 5, 6, 7]. Measure the distance over five grooves to determine "D" [8]. Measure the distance between the edges of the five grooves [8]. Complete the worksheet in Supplement B of this Guide. Using quantities calculated on the worksheet, answer the questions near the bottom of the results sheet to determine whether the grooves conform [10, 11]. Manufacturers are advised to use actual widths in these calculations [12]. Follow the steps on the results sheet to reach a decision on the club, repeating the measurement if necessary [11]. * * * Note: Consult the full instructions for grooves with inconsistent spacing, or other unusual features [12, 13, 14].