Jiu Jitsu Gis are ranged from A0, – A6 for adults and K0 K4 for kids. Those are a lot of choices on the sizing of your Jiu Jitsu Gis so it is very important to choose the right size. For example, you might be a size A2 in one Jiu Jitsu Gi brand but an A3 in another. This is why sizing is very important and if needed you should call the company itself and ask them about sizing. You can tell them your exact measurements over the phone or email and most companies will be happy to assist you with the correct sizing.
Some may ask, well what about shrinkage? That is a very important question. Shrinkage of your Jiu Jitsu Gis may also play a big factor in the size. Some Bjj Kimonos come pre-shrunk where there is minimal shrinkage and others are not pre-shrunk so there may be a lot of shrinkage of your Bjj Gi. Generally if you were to hang dry your Bjj Kimonos you will never see any shrinking of your Gis. So make sure you note which Bjj Kimonos are pre shrunk and which ones are not and play that fact into deciding your size. Again, if you are still having trouble with size then the recommendation would be to contact the company directly via email or phone.
For you to understand a little better I have provided a sample sizing chart I got off a Jiu Jitsu Gi website :
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