The calculator just gave you a safer place to start but after doing a lot of trim flights you may find the 25% rule of thumb is where you end up. I'm like John and on any constant cord plane I usually go right to the 25% mark but with swept wing or tapered wings I use the Calculator to start with. I was given a pattern plane and used the calculator and it was right where I liked it and never made a CG change. I tried a few different places but it ended up at the original spot.