There is no rule of thumb per say because everyone has a different golf swing speed. But, for people that play regular flex golf clubs (swing speed between 75-85 mph), the average lengths of golf clubs are as per follows. There is usually an 8-12 yard difference per club at the normal swing speed with standard lofted clubs. 3-190, 4-180, 5-170, 6-160, 7-150, 8-140, 9-130, PW -115, GW-100, SW-80, LW-60.
You must also take into account that all golf clubs are not lofted the same. For a long time the average pitching wedge was 48 degrees of loft. Now you will find PW´s that are 46 or 44 degrees. Same with the other iron golf clubs. This may cause one to think that they hit this brand of 7 iron 5 or 10 yards further than this other brand, that is true but are you really hitting a 7 iron, a strong 7 iron or a 6 iron that has been stamped 7?
