I've done from hairline to ends, but that makes my hair seem so much longer than it is (15.2 inches). I prefer to do an all over measurement, and when I do it that way I have three different measurements.
I don't measure anymore as I just couldn't get it accurate each and every time. I use certain areas on my body to judge if my hair has grown and how far away it is from bra strap.
In terms of inches I wouldn't be able to tell you. I've got about 4 inches to go till bra strap length.