The draw weight will be different between 25.5 and 26 " Try to get the same draw length on every pull . Try to find a good anchor point that doesn't chance a 1/2 inch . Hold your bow the same way every time when you pull back the arrow . 1/2 difference is a lot and it will give you a different draw weight . Once you figure out what length you shoot then mark it and pull the string back with the arrow to the mark and look at the scale and you wil know your draw weight of that particular bow . No 2 bows are going to be the same . If you are wanting to know your draw weight for that bow for arrow choices a few pounds one way or another isn't going to matter that much , you just want to be in the same ballpark as the spine of the arrow . At my draw length my bow is 27 lbs and it shoots arrows from 600 to 800 spines . Its best if you just go by the bows 30 lb weight and start off with the spins that work in that range for the length arrow you need . I need a 31 " arrow for my long bow . I'm in the process of trying to find the lightest weight arrow in the 5.5 to 6.5 gpi that come in a 31 " length so I can have the flattest trajectory possible for 3D target matches . I'm looking between 600 and 800 spine arrows .