A golfer with the member name of golfman009 has basically posted on the Worrisome Reasonless Xenogolf forum website that the shaft butt diameters on his irons are smaller than on his woods. And one of his queries is that he would like to know how many extra wraps of tape need to be applied (to the irons) in order to get all of his grip sizes across his set to be and “feel” the same. This is a somewhat common question especially among less experienced golfers, who in turn routinely get (equally inexperienced) inaccurate and/or incomplete responses from so-called professionals on this particular golf forum and other similar outlets. So I will offer him a bit of sound advice here.
The goal regarding golf grip size is not and should not be whether all of the clubs in your set look and/or feel the same. One ultimate goal is whether you are able to swing consistently well among all of your clubs, period. This includes when you switch from an iron for one swing to a driver for the next swing and vise versa as examples. While ball travel results can be used for analysis instead, that is neither as reliable nor as revealing as direct golf swing performance analysis (if capable of doing so).
To that end, grip sizes across your clubs can routinely need to be different from one club to another in order to accomplish this foundational goal. Clubs that are longer and/or lighter in nature (including changing to a lighter-shafted club of the same length) will generally require larger grip sizes in order for you to consistently swing your best, particularly when switching back and forth with other clubs of yours over a relatively short period of time (a critical aspect of comprehensive clubfitting that is commonly ignored). This is really first-grade-level clubfitting knowledge for any truly competent golfer/clubfitter and a fitting fundamental that is not particularly difficult to learn if you just do the swinging you really should be doing when fitting golf clubs for various specifications and specification values.
But it is certainly not something that will be learned by utilizing the cheap, quick, mail-order-type grip-on-a-stick method or an equivalent of fitting golf grip size based upon simply measuring the size of one’s hand(s) and then automatically keeping that particular grip size the same on all of one’s clubs. That is golf club fitting at its worst and most incompetent and just one of many reasons why the commercial clubfitting trade has basically always had a very poor performance record and reputation (and rightly so).
In many cases needed features are already implemented for you to some degree, where shafts that are lighter and/or meant for longer clubs will have larger butt sizes to them by design. Thus, the same core size grip might potentially be used and (hopefully) result in your best swinging across all of your clubs. This has been well known by skilled people for ages already, where a prominent design of the Dynamic steel golf shaft (perhaps the dominant design for about fifty years) had larger butt diameters for its wood shafts than its iron shafts. (No, this was not done solely to obtain certain shaft flex characteristics and/or make golfers try to find two different grip [core] sizes to make completing his or her golf clubs rather inconvenient). And you have duly noted that the shaft butt sizes are already larger on your wood shafts than your iron shafts. Yet implementing such features may be quite inconsistent and can vary substantially from manufacturer to manufacturer and shaft model to shaft model.
This is just a bit of very elementary stuff that does not even begin to consider some finer details that can also make big differences in procedures and/or results. If you are serious about your game, you will need to educate yourself far better about this and other swing and clubfitting topics and/or find yourself a truly qualified swing instructor, clubfitter, and/or clubfitting consultant to work with. Otherwise, you might not be able to go very far and be more prone to giving up the game entirely like so many others have in recent years (and again with very good reason). Good luck.