I agree with the Mann, that most measurements are taken while flexed but you'll get even better results after an arm work out while the muscles are engorged with blood. I wouldn't have it any other way Some hardcore arm blasters will give you their size both cold and flexed. However, there are some other methods being used out there, like the round up to the next inch method. Theres also the magazine supplement add method where the photo director tapes back an inch or two on the tape so the picture of the measurement show a couple of extra inches. There is also the big time bullshitters out there who make all sorts of claims but just never measure up when called out. 20 inch arms are not that common, that is big when you see it live. They are out there. I am training to get there!