A Guide to the Rules on Clubs and Balls

Impact Area Markings

If a club has grooves and/or punch marks in the impact area they must meet the following specifications:

(i) Grooves

• Grooves must be straight and parallel.
• Grooves must have a plain*, symmetrical cross-section and have sides which do not converge.
• The width, spacing and cross-section of the grooves must be consistent throughout the impact area.
• The width of each groove must not exceed 0.035 inches (0.9mm), using the 30 degree method of measurement on file with The R&A.
• The distance between edges of adjacent grooves must not be less than three times the width of the grooves, and not less than 0.075 inches (1.905mm).
• The depth of each groove must not exceed 0.020 inches (0.508mm).
• *For clubs other than driving clubs, the cross-sectional area (A) of a groove divided by the groove pitch must not exceed 0.0030 square inches per inch (0.0762 mm2/mm).
• Grooves must not have sharp edges or raised lips.
• *For clubs whose loft angle is greater than or equal to 25 degrees, groove edges must be substantially in the form of a round having an effective radius which is not less than 0.010 inches (0.254mm) when measured (using the two circles method), and not greater than 0.020 inches (0.508mm). Deviations in effective radius within 0.001 inches (0.0254mm) are permissible.

(ii) Punch Marks

• The maximum dimension of any punch mark must not exceed 0.075 inches (1.905mm).
• The distance between adjacent punch marks (or between punch marks and grooves) must not be less than 0.168 inches (4.27mm), measured from centre to centre.
• The depth of any punch mark must not exceed 0.040 inches (1.02mm).
• Punch marks must not have sharp edges or raised lips.
• *For clubs whose loft angle is greater than or equal to 25 degrees, punch mark edges must be substantially in the form of a round having an effective radius which is not less than 0.010 inches (0.254mm) when measured using the two circles method, and not greater than 0.020 inches (0.508mm). Deviations in effective radius within 0.001 inches (0.0254mm) are permissible.

Note 1: The groove and punch mark specifications above indicated by an asterisk (*) apply only to new models of clubs manufactured on or after 1 January 2010 and any club where the face markings have been purposely altered, for example, by re-grooving. For further information on the status of clubs available before 1 January 2010, refer to the “Equipment Search” section of www.randa.org.

Note 2: The Committee may require, in the conditions of competition, that the clubs the player carries must conform to the groove and punch mark specifications above indicated by an asterisk (*). This condition is recommended only for competitions involving expert players. For further information, refer to Decision 4-1/1 in “Decisions on the Rules of Golf”.

These Rules were updated in 2010 and many pre-2010 models of clubs do not meet the new specifications. The above Notes mean that the vast majority of golfers can continue to carry clubs manufactured prior to 2010 until at least 2024. Full details of the phased introduction of these specifications can be found at www.randa.org/equipmentrules.

Supplementary Paper B sets out guidance on how to measure width, depth and separation of grooves using the ‘ink and scratch’ method and how to determine the conformance status of a club to the pre-2010 Rules. This is an adequate method for use in the field where the Committee has not introduced the Groove and Punch Mark Condition (i.e. at the non-elite level).

There are many methods which can be used to measure grooves and punch marks against the new specifications as detailed above – most of which require specialist equipment.

Full details of the procedure for measuring club face markings and determining their status against the post-2010 specifications can be found on The R&A’s website. A summary can also be found in Supplementary Paper C.

A field test has been developed in order to assist golfers and Officials involved in elite level professional golf in determining the status of clubs available prior to 2010. Where access to a field test is not available, The R&A has compiled and published an informational database of pre-2010 iron models, as well as hybrid and fairway woods with a loft of 25 degrees or more, which have been submitted and evaluated against the 2010 Rules. Unlike the List of Conforming Driver Heads (see Section 8 - Spring Effect and Dynamic Properties), this database is not the focus of a Condition; it is purely intended as a reference tool. The database can be accessed via The R&A’s website.

Clubs where the face markings have been purposely altered, for example, by re-grooving must conform to the 2010 groove specifications. However, clubs which have only been refurbished back to their original state (perhaps by light sandblasting) may still benefit from the period of grace given to pre-2010 models.

For the avoidance of doubt, all clubs manufactured after 31 December 2010 must conform to the new Rules.

(iii) Groove/Punch Mark Combinations

If punch marks are used in conjunction with grooves, the following guidelines apply:

Iron Clubs:

• Small punch marks which are in line with a conforming groove, and which would be totally contained within a continuation of the groove do not have to meet the punch mark to groove specifications (See Figure 35). However, if the diameter of such punch marks exceeds the width of the groove, then they must meet the specifications.

Fig. 35

Fig. 36

• When measuring the centre to centre distance between a punch mark and the end of an in-line groove, the centre of the groove is deemed to be half a groove width from the end edge of the groove (See Figure 37).

Metal Wood Clubs:

Provided the following three conditions are satisfied, the above interpretation of the specifications for punch marks in line with a groove may also be granted for metal woods, even if the punch marks would not be totally contained by the continuation of the groove:

• there must be no more than three in-line punch marks in the part of the groove that is missing (i.e. in the gap between the ends of the partial grooves);

• the combined area of all of the in-line punch marks in any one such gap must not exceed the area of the missing groove; and

• the separation of the in-line punch marks from adjacent parallel grooves – measured from centre to centre – must be at least four times the width of the groove.

The following diagram attempts to illustrate each of the above conditions:

Fig. 37 - Exceptions for Metal Woods